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Speaker 2: Now get ready. Here is your host, Paul Abernavi. Up.
What up? Everybody? Welcome to another episode of Master the
NEC podcast, where I talk about the National Electrical Code
and all things electrically related. On today's episode, it's a
special one because we're gonna be talking about mastering apacity
the Ultimate Guide to Understanding table three sixteen, as well
as all of those other little nuanced tables like three
ten fifteen B one one or three ten fifteen C
one when it comes to learning apacities of conductors in
the other different aspects of it being temperature limitations, terminal limitations,
and all that good stuff. So there's a lot of
stuff we're gonna try to we're gonna try to unpack
in today's episode. So hopefully you're enjoying this podcast on
whatever platform you enjoy, but remember you also can get
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check it out. It's free. Just go to our website
and pick it up and we'd love to have you
there in the old app family if you will. All right,
so today we're going to be digging into that. We're
gonna focus on conductor's capacity. We're gonna be focused on
obviously opacities. We're dealing with three ten sixteen. That is
the table when it comes to conductor opacity. Now, a
lot of people ask me to say, Paul, you should
say what code cycle you're on, and I typically do.
Today's show is going to be based on the twenty
twenty three edition of the Nationalisical Code. But just understand
that depending on which code cycle you're on, the apacity
table may change three ten fifteen B sixteen. It may
be three ten sixteen for whatever cycle you're in. But
we're talking opacity today, but everything else that we deal with,
it's all going to be really based on the twenty
twenty three edition of the Nationalisical Code. Now, with that said,
the fundamentals do not change. So what we're talking about,
the important things of the ambient temperature corrections and adjustment factors,
terminals and terminal ratings and the ampasities in themselves. That
doesn't that hasn't changed. That's not going to change even
with code cycle changes. That's really not So we're not
changing the apacity of conductors right now. We're not. You know,
most of the manufacturers are wiring cable are pretty content
with where the opacities are, so none of that's really changing.
So just again don't stress out saying, oh, well, I
don't want to listen to that because they're talking twenty
twenty three. If you're on the twenty twenty, it's still
going to be applicable to you. And also I should
mention before I get into this that if you really
want a detailed video with explanations and examples, you may
want to consider subscribing to fast tracks Tube. It's just
the same as fast Track system, it's just with Tube
on the end. So fast tracks tr ex tube tube
dot com. That's our video platform, and there's a lot
of very tailored videos over there. It's not the garbage
that you'll get by just randomly searching on YouTube. I
guess I shouldn't say it's all garbage, because I do
have some videos up there and I don't consider that garbage.
But you get more. We're detailed less, no commercial type
of things over on our fast tracks tube. It's also
available on fasttrackstv dot com by the way, right, So
that's what we're focusing on today, and we're talking about that.
But by the end of this episode, you'll understand sizing conductors.
You'll understand the nec when it comes to opacities and
limitations based on the terminal ratings and temperature and all
that kind of stuff. So we'll try to give you
as much as we can in this episode so that
your takeaway is that you're a little bit better than
you were when you started, okay, before you started this episode.
That's our goal. That's what I'm trying to do anyway.
All right, let's start off first and understand the structure
when it comes to the ampacity tables three ten sixteen,
which again there's other ampacity tables three ten, seventeen, three
ten eighteen, three ten nine, but the most common one
used for zero to two thousand volts applications, the primary
EmPATH city table that you're going to use, especially if
you're implementing adjustment and corrections to a apacity value is
going to be three ten dot sixteen. Okay, Now it's
important that I tell you table three ten dot sixteen,
because there's obviously a section three ten dot sixteen which
gives you some of the backbones that reminds you that
it's based on thirty degrees sales cus eighty six degrees
hit fahrenheit. It's based on not more than three current
care and conductors. That's under the normal three ten dot sixteen,
not the table now. Years ago it was also incorporated
into the table, but the way it is now, that's
the code reference in the code, and then you go
to the actual table to actually see the actual opacities.
So I just want to make sure you understand that
just because we say table three ten dot sixteen, there
is an actual three ten dot sixteen in the code
that gives you a little more of the backbone behind it,
and that is the again not more than three ambient
temperature thirty degrees salesiase eighty six greeze fahrenheit zero to
two thousand volts. All of that. It gives you that
in the code so that you can adequately use table
three tens sixteen properly, Okay. Just want to make sure
that we understand that before we get too deep into it.
Now three ten sixteen the table is broken down into
aluminum on the left, copper I mean aluminum on the right,
copper on the left, and it's broken down into a
sixty seventy five and a ninety degree column. Now, the
sixty degree column is used for sixty degree terminations limits. Okay.
Now this also is going to be applicable, for example,
to non metallic sheath cable under three thirty four dot eighty.
It's going to say that you know what, I'll let
you and we'll see later. I'll let you do adjustment
and corrections from the ninety degree opacity, but that's only
for adjustment and corrective purposes, and that is when it's
not thirty degrees salesiusir eighty six s greeese fahreheit, or
it's more more than three current current conductors. Right then
if it's that way, I'll let you use the ninety
to do these adjustments or corrections. But ultimately, at the
end of the day, my temperature limitation is still going
to be or my apacity limit is still going to
be in the sixty degree column. Just because we're gonna
let you do something, you're still going to be limited
to sixty degree c okay. And that also is going
to apply for one hundred amps. Uh, for less than
one hundred amps, okay, so that's going to be one
ten dot fourteen C one A three for example, is
when we're dealing with the limitations when it comes to
terminals in temperature. So and we'll cover all that, but
I just want to kind of set the tone. The
sixty degree column is again, typically when you've got under
one hundred amp application, when you have a missing link,
in other words, you don't know what the terminal rating is,
but you know it's under one hundred amps, then you're
going to be defaulting to the sixty degree column. Okay,
those type of things. We have a seventy five degree
and that's the most common used for again one hundred
ants or more. But also you'll find that even if
the conductor is let's say a smaller conductor like a
fourteen gauge thhhn, that if the terminals rated seventy five,
if the insulation on the conductor is rated at least
seventy five, and of course THHCHN would be at least
seventy five. It's ninety dry. Okay, then you're going to
be able to use the seventy five even though it's
technically under one hundred ampiers. Okay. So that's why it's
so important to understand the nuances. Okay. Now again, the
caveat to that is if you had fourteen or twelve
inside of a nonmetallic sheaf cable, then that rule doesn't apply.
It's still going to be limited to the sixty, even
though you could do adjustment of corrections from the ninety.
This is single insulated conductors. We're just talking just regular
THHHN that you would pull in a raceway. Okay, if
your terminals are rated seventy five, if your insulation on
the conductor's rated at least seventy five, and if the
terminal at the other end of whatever it's connecting to
on the equipment is rated at least seventy five, even
if the ampacity was less than one hundred, you still
could use the seventy five degree column. Why, because everything
is rated seventy five or greater. That makes sense. So
these are little nuances that you have to learn, and
they can be very impactful because you know, if you're
preparing for an electrical exam, and it may give you
everything in the equation to size a conductor, but it
ultimately does not tell you the terminal rating. And if
the ampacity is under one hundred, it doesn't matter if
it's thg in. If the ampacity is under one hundred,
and then they didn't tell you what the terminals are
rated at, then guess what, Because it's under one hundred,
you're going to be locked in the sixty degree column
far as ampacity is concerned. Okay, So it's important to
understand those those nuances. And again i'll remind you we
do have a great video called de Rating Demystified over
on fast track Tube if you're interested in that, and
again it's ninety nine bucks a year. It's your way
of saying thank you to us. It helps us continue
to go and it's you know, you help support the program.
So we appreciate all of you that subscribed to that. Now,
if you're in our fast Tracks program and you purchase
the enhanced program, then you already get twelve months. Our
hope is that you'll renew it. At the end of
a year and keep that fast Tracks Tube subscription because
you find it is important. We're hoping that you do.
And of course you have the ninety degree column. Now,
the ninety degree column is typically used for adjustment and
correction purposes. However, it's important to realize that you could
in a real world scenario, you could have a conductor
insulation that's rated ninety. You could have a terminal that's
rated ninety, and you could have a piece of equipment
at the other end that has terminals on it that
are rated ninety. Guess what if that's the case and
I can use the capacity from the ninety degree column. Yeah,
because everything is rated ninety noil. Again, just for clarity,
that's not gonna apply to non metallic sheet cable because
that only lets you use the ampassity under ninety two
do adjustment in corrections, which ultimately it's not going to
have more ampacity that's under the sixty degree column. Okay, Okay, Again,
I understand it's going to be a large collection of
people out there that even if I explain this in
the first twelve minutes of this video or podcast, you're
still not gonna get it. And you're gonna say that
was confusing. You know what. Haters are there anyway, so
I can't do anything about it. All I can do
is say, go back, re listen to the first twelve
minutes of this podcast, and then maybe go watch our
d rating de mystified video and it'll eventually once it
locks in, it'll lock in, okay, and you'll get it.
I'm doing my best here to try to convey it
for you. But again, that that's the concepts Now, let's
look at some basic uses of table three ten sixteen's.
Let's say you need a conductor that carries fifty ampiers
and we're just gonna go with what we have. Okay,
we're just gonna take it at face value. The conversation
we're not talking right now about in the use in
the in the field. That's the other thing that you
have to remember. If you're doing exam prep, is it
a lot of times they'll ask you a question. Don't
let your mind wander to what you would do in
the field. Only answer the question that they give you
on the exam based on what they give you. Don't
let your mind wander. Okay. So you're like, okay, even
if you're thinking, even if I don't have all the details,
when I'm trying to answer a question on an exam,
your mind starts going left and right, up, down, and
you start stress starts getting built up, and it's like,
calm down, relax, I'm gonna give you some I'm gonna
give you some understandings here, okay, and we're gonna give
you what your nobel to really see in the real world. Here.
So I have a THHHN. It's ninety degree c rated insulation.
That's what the T T stands for thermoplastic. The H
is if you had only one H in there, like THHN,
I mean, excuse me, THW, that would be seventy five.
But since I have two h's, that's ninety in a
dry location.
Speaker 1: Uh.
Speaker 2: And then you got the N which is nylon. So
two h's high heat. Just remember high heat. That's ninety
T thermoplastic. And the N is a nylon and that
is just a covering that gets extruded over the insulation.
And the nylon has absolutely zero insulating value. It's there
to protect the insulation when you're pulling in at a raceway,
and it reduces the coefficient of friction, so it makes
it a little easier to pull in conjunction with pulling lubricant. Okay,
it has no insulating value. So if you get some
nylon that's scuffed up, scratched or whatnot, unless it's an
oil and gas environment. And when we say that, we
mean if you're installing THHHN in an oil and gas
environment where it is a likelihood that it will come
in contact with oil and gas because of the environment
to where it's being installed, then the nylon can't be damaged.
But anywhere else in ninety nine percent of your normal installations,
it doesn't matter if the nylon gets eaten up during
the installation. In fact, it served its purpose. It protected
the insulation. But just don't misconstrue the nylon as actually
being insulation because it's not. It's just a covering, that's it. Okay.
So in our case, let's say we need a conductor
that carries fifty amps, we're gonna be using THHHN copper.
And oh, by the way, for those that are on exams,
if it doesn't say copper, you always assume copper.
Speaker 1: Uh.
Speaker 2: Don't ever let your mind wander to illuminum, even though
the answers might give you an answer. In aluminum, it's
copper always the first you go to unless they state otherwise. Okay.
In the real world you choose whatever you want, okay.
But in an exam, if they don't say the conductor material,
then you just assume copper. Okay. Here I am giving
you an assumption rule. Always assume copper unless they state otherwise. Okay.
So we have thjh in it's ninety degrees rated. But
most equipment that you're going to find out there today
is not going to have a terminal that is rated ninety.
Now that's not to say Polaris splices, those lugs, okay,
those type of thing inline terminal blocks that you might
find and that goes in wireways, they might be rated ninety,
but typically on equipment, they're not going to be rated ninety.
They're usually going to be seventy five degree c Now
occasions back in the day, you would see sixty slash
seventy five, But to be honest with you, if it
says sixty slash seventy five, then you could ignore the
sixty and you'd use the seventy five. You get what
I'm saying. So even though it's thhhn, and we know
it's ninety degree rated insulation. Okay, And we're not even
talking about opacity tables right now. We're just talking conductor.
It's ninety degrees CE rated. But you're going to be
limited because most of the terminations are going to be
seventy five degrees C. And again in your panel, electrical panel,
most all of those terminations on breakers are all going
to be at least seventy five. Okay, So that's why
we're using real world scenarios here. Now step one, we're
gonna use a seventy five degree column and you're thinking,
wait a minute, Paul, it's fifty ampiers So one ten
dot fourteen and don't do me a favor. Paul's the podcast.
Go look at one ten dot fourteen C and go down.
And you're saying, okay, it says if it's under one
hundred AMS, then I'm stuck on the sixty Why did
Paul go to the seventy five? Well, the reason we
did because again, the vast majority of your terminations are
rated seventy five. Even though the temperature rating on the
conductor is ninety, we know that we can't use that
ninety in to start with, we're going to be limited
to the seventy five because of the terminals. Okay, they're
rated seventy five, whether it's at the breaker or whether
it's at the piece of equipment whatever. Okay, so we're
gonna use the seventy five. So let's look in the
seventy five degree column to find our apacity first, okay,
and we want to make sure that it is greater
than or equal to fifty am yeers, all right, So
I've got my codebook here. I'm gonna go down to
the codebook and I'm gonna go down to three ten,
sixteen and do it with me. If you want to
get better and you're listening to this podcast, pause it
and you know, take your time and go down and
work through it. So you'll see that an eight gauge
copper under the seventy five degree column is good for
fifty amps. And you'll see that a six gauge is
good for sixty five ams. So in our case, the
eight awg copper thjhen is good for fifty am. It's
fifty ams. Now that is only good, folks, under this column.
It is only good if it is not more than
three current car and conductors. And again this is why
you got to go look at the actual three ten
sixteen to understand those limitations. Okay, Now, the good news
is if you're using link or or you're studying with
the NFPA document, or you're in the NEC, then the
three ten sixteen is near the table, so it's it's
you know, they're right near, right next to each other,
so it's not a not brain surgery. But if you
go look in the twenty twenty three edition of the NEC,
you're gonna see four things there. You're gonna see number one.
In order to be able to use three ten sixteen,
the conductors are rated zero vaults through two thousand vaults.
That's number one. Number two, the conductors are rated either sixty,
seventy five or ninety. Check number three. It's as wiring
as is installed in at thirty three EC eighty six
degrees ambient temperature. Probably not what you've got, okay, but
let's start out right now. Say yes, it's thirty degrees
ambient celsius or eighty six degrees fahrenheit, right, so we're good.
And then it says the equipment is rated seventy five
degrees C. And so we know what our equipment rating is.
And again, the vast majority of in the field equipment's
going to be at least seventy five degrees C. Right now,
there's exceptions to every rule. There are lugs that may
be rated ninety, there may be lugs that are limited
to sixty. But again, I can't cover everything in a podcast,
and there's always a hater out there that's going to say, well,
he didn't say this whatever. Then I eagerly encourage them
to create their own podcasts and do whatever the hell
they want to do. But I got to do the
best I can to keep it rolling. So we're gonna
go with seventy five degree terminals. Okay, So into that
scenario is in that perfect world, okay, thirty degrees celsius,
eighty six trees fahrenheit, terminals rated seventy five degrees C
and no more than three current current conductors in that raceway,
then I'm gonna say the eight copper is good to go.
It's good for fifty amps. We are good to go
based on the criteria that we have so far. Okay,
now let's take this to another level. That's a perfect
world scenario. Now, by the way, if the lugs were
sixty degree rated, okay, or I'm in a job site,
I go to a job site, I can't tell what
the lugs are rated at either end, How would I
apply this to that same scenario? Even though it's thhn,
it's ninety degree C. I'm not going to assume the
seventy five degree conductor rating. I mean the terminal rating.
So I'm going to say, well, since I can't verify
that in the real world, all I can look at
and go, well, yes, the insulation a conductor is over
seventy five, but I have no idea what that terminal
rating is. I can't tell I can't see it. Or
I may be able to see the breaker, but I
can't tell by the equipment. Well, in that case, even
though it's thhhn, you're gonna have to fall to the
six degree column, why because one ten fourteen C one
he tells us that. So in that case, if I'm
locked into the sixty degree column because I have of
a lack of information, then I got to go down
and say, okay, I still got to cover that fifty five.
So in that case, it would be a six gauge
because that is good for fifty five amps, so it
can easily handle the fifty, whereas an eight gauge is
only good for forty. You see what I'm saying. That's
how you have to mentally think about it, and you've
got to know all these pieces. Folks. I've told you
this in many podcasts that one of the hardest things
for people to grasp is opacities and adjustment and corrections
and how you would maneuver back and forth understanding apacities.
It's tough, it's not easy, and it's it, but it
is easy to make a mistake. Okay, okay. Now let's
go on to adjustment and corrections. Okay, And this is
where a lot of people start to tumble along the
side and it gets confusing for them. So let's start
out with understanding some fundamentals. So what we're going to
talk about is adjustments. Now, what is an adjustment. An
adjustment is the number of current current conductors that you
have in a race way, in a cable bundled together,
things like that, if you're going to have more than
three okay, okay, more than three, or let's say four more,
you're going to have to make an adjustment to the
opacity of that conductor. So it's not going to have
the same apacity that you started out with because there's
going to be mutual heating. That means you've got other
conductors more than three. It's obviously not optimal for three
ten sixteen, So you're going to have to modify the
apacity that's the baseline of this table in some way,
and that's what we call an adjustment. So I could
have four current current conductors in there, I could have
five current current, I could have six, I could have ten.
All of those current current conductors over three are going
to play a role on how much actual current that
those conductors that are together in that raceway can carry
or in that bundle of cable. It's going to have
an impact on that. Now where do we see that at?
So if you're new to the code, and you know,
maybe you're studying in your first time, then you're going
to get familiar with three ten dot fifteen and three
ten dot fifteen is kind of giving foundational information about bundling,
about the number of current carer conductors, all these type
of things, So get familiar with it. But the first
one we'll look at is three ten dot fifteen C. Now,
three ten dot fifteen C is talking about again adjustments,
And I'll read it to you from the code so
that you understand it verbatim. It says three ten dot
fifteen C adjustment factors C one. It says more than
three current carrent conduct So that is the trigger here.
If it's not more than three current car conductors and
the ambient temperature is still thirty degrees salesius eighty six
streets fahrenheit, and guess what, you just pull opacity straight
from the table. Happy, Happy, and you just go on
your merry way. But if there is something in there
that's going to require a trigger of an adjustment, you
got to understand how to do it. And here's what
the code says. It says the opacity of each conductor
shall be reduced as shown. Okay, so it's telling you
right away the apacity baseline in three ten dot sixteen
is going to get reduced based on the values that
are given in a table. And that table is three
ten fifteen C one and it says where the number
of current carent conductors in a raceway or cable exceeds three,
or where single conductors or multiiconductor cables not installed in
a raceway. That means they're cables like nonmatology cables that
are just you know, tie wrap together in a big
bundled mass, that type of thing. They're installed without maintaining
spacing continuously and links longer than twenty four inches, so
I'm basically anything over twenty four inches. If they're not
maintaining spacing, then they're bundled, and that's going to affect
the opacity of those conductors that are in those cables
because the heat can't dissipate it's locked in this bundle, right,
So that's it's going to affect what the apacity is
of that the conductors that are in that massive bundle.
You get me all right? Now? It says every current
carrying conductor of a parallel set of conductors shall be
counted as a current carrying conductor. Right, So if I
have a parallel sets of three blacks, three reds, three blues, okay,
then every one of those conductors are considered current carry conductors.
So if I have three sets, three blacks, three sets,
then it's three blacks in a raceway whatever, they would
all be considered current carent conductors. Basically what you're saying, Okay.
Now it goes on to say where the conductors of
different systems are provided in three hundred dot three are
installed in a common raceway or cable, it says the
adjustment factor shown in three ten fifteen C one shall
apply only to the number of power and lighting conductors.
So that's a situation where you may have other conductors
let's say signaling and control that actually have the equal
insulation rating on it. Maybe it's the same insulation rating
ninety degree C as the power in lighting, but they're
not power in lighting, so you don't count those as
current current conductors. Okay, You're only going to apply it
to the power in lighting conductors because they're the ones
that are going to generate significant heat. Okay, So that's
what it's saying. Okay, So that's the basic and of
course I will tell you that C one also goes
down and talks about what you have to do for
cable t It reminds you of adjustment factors shall not
apply to conductors in raceways that have a length of
not exceeding twenty four inches. So if you have like
what people call a nipple and many people say, well,
and nipple's eighteen inches or nipples twenty four inches. Get
out of that mode. Really, it's go by what the
code says. The code's not calling it a nipple here,
it's just giving you a distance. So I could have
a twenty four inch or less raceway between two boxes,
and yes, I might have a problem with raceway, phil,
but I don't have to apply adjustment factors that apply
here when it's only twenty four inches or less. Why
because it's short enough that the heat's going to dissipate
out of it. Now, you're still gonna have raceway pill
issues that you got to be aware of, and you
could have an ambient temperature that you're gonna have to
do a correction for. But you just don't have to
worry about the adjustment because it's such a small raceway. Okay,
I just want to want to point that out. Also,
you have other things for underground conductors as emerged and
leave from a trench, you got some relaxation for that.
You also have relaxation for AC cable and MC cable.
It's very strict caveats that you have to meet, whereas
you can't a cable overall, doesn't have to can't have
any PVC jacketing on it. It's just metal. Also, we're
talking MC or AC by the way. And then the
cable is not more than three current carry conductors in
each of the cables, the conductors inside of it are
at twelve gage and not a fourteen or not a ten.
They're all got to be twelve and in as long
as your bundle is not more than twenty current carrying
conductors that are stacked or supported on bridle rings that
act like they're being bundled. As long as you're not
exceeding twenty current carry conductors collectively with all of the cables,
then you don't have to apply this adjustment. So that
can help you out in a commercial environment. Just got
to know how many MC cables you're putting together, so
you don't bridge this, and you got to make sure
that you meet all these caveats, and you can ignore
this adjustment factor. Again, that's not removing the ambient correction.
This is just an adjustment rule that you get to ignore. Now,
if none of these applied, then you know you still
are going to have this. If any of these allowances
don't apply, and you just have a raceway with conductors
in it, and you exceed three current carry conductors, then
you're going to have to do an adjustment. And what
is that going to fundamentally do. It's going to reduce
the current carrying ability of that conductor. And if you
put a lot of them in there, ultimately you can
end up with a conductor that can't carry any current.
And you think, well, it's still a conductor, it can
obviously carry current. Yeah, but if the conductor is now
compromised because you violate the code and now it has
mutual heating, it's a matter of time before that insulation
will break down and fail. And then somebody like me
comes along, gets hired as an expert witness, and then
we find out you didn't follow the code. And of
course it may not be the reason the building burned down,
but guess what if we can tie back to something
you did wrong. Insurances love that, and we as experts
get paid good money to point the blame at other people.
So just follow the code. Make it simple, Okay, So
let's look at some example. Well real quick, let's jump
to the other Let's let's cover these first, and then
we'll give you some order of how you do these
and how you would calculate these outs things to think about.
So that was the adjustment issue in three ten fifteen C. One.
Now let's let's talk about the correction issue. This is
where the ambient temperature that you're placing these conductors in
are not in alignment with the general rules of three
ten sixteen. So I'm putting these conductors at this capacity
in an environment, in this race way, in an ambient
temperature that is other than thirty degrees celsius and eighty
six streets parrit which is be honest with you, probably
inside of a building that's conditioned space, you don't worry
about it that much when it comes to the ambient
because it's typically you know, it's a typically it's not
something you think too much about. You think more about
the adjustment than you do the correction. Now, if I'm
taking a raceway and I'm taking it through let's say
a boiler room, or I'm taking it through an area
where we have a actually known documented elevated ambient because
of the environment that I'm going into, that's different because
that is going to have a direct impact on the
ambient temperature as well as the annular temperature inside of
the actual raceway itself, and so that's going to affect
the opacity of that conductor. Now, how does it affect it? Well,
what we have to go look at now is three
ten fifteen B one And when we look at three
ten fifteen B one, which is going to ultimately tell
us that we're going to be looking at table three
ten fifteen B one one or three ten fifteen B
one two. Now, again this is for the twenty twenty
three edition of the neec UH. Before it was just
three ten fifteen B one. In three ten fifteen B two,
they're the same thing. Okay, it's just number of changes.
So again, if you're in an older edition, don't let
it spook you. It's the same concept, same fundamentals. It's not,
you know, not anything more complicated than that. Now, one
question I get from people that they ask me, Paul,
what is the difference between three ten fifteen B one
one and three ten fifteen B one two. What's the difference. Well,
you're going to be used in three ten fifteen B
one one for ninety nine point nine nine nine nine
percent of your applications, because that aligns itself with a
thirty degree C eighty six degree fahrenheight baseline opacities. You'll
notice if you look at three ten fifteen B one
two that in the header of the text of the
title of the table, you notice it says for ambient
temperatures other than forty degrees C, whereas the three ten
fifteen B one one says thirty degrees C. That's because
under table three ten sixteen for ampacity, Remember I told
you that it's based on the baseline of thirty degrees
sales is s eighty six street fahrenheit. So when we're
adjusting or in this case for the ambient temperature we're
correcting from the baseline apacity, we're going to be doing
it based on the value that's under the thirty degree
c baseline of three ten sixteen. So you're saying, well,
when would I use three ten dot fifteen B one two, Well,
that is if you're using other tables, for example like
three ten dot eighteen, three ten dot nineteen, those type
of tables, Well, if you're using those, then they're going
to have a different ampacity value baseline on those ampacity tables.
So if you were to take a second and just
go look under the tables. For example, go look at
three ten dot seventeen. You'll notice that three ten dots
seventeen is still based on thirty degree C eighty six
treees heronite. So even three ten dot seventeen, which is
again single insulated conductors in free air, the opacity is
still going to use the correction table three ten fifteen
B one one. But if you go down and look
at three ten dot eighteen, you'll notice remember at the beginning,
not in the table, but at the beginning the charging statement,
the one, two, three, and four the caveats. If you will,
you'll notice that it's based on forty degrees C. Same
thing with three ten dot nineteen. It's based on forty
degrees C, which aligns itself with the opacities of this table,
align itself with the correction table three ten fifteen B
one two. If that makes sense. That is something that
many people, and there are some people out there that say, well,
go on and take your pen or marker and mark
out three ten dot fifteen B one two. I would
never tell you to do that, because you just never
know when an obscure question is going to come on
an exam that you're going to need to use that table,
and I would not want to do anything that's going
to draw my attention away from it and think I
never would use it. But for all of your in
the field, all of your practical uses, you're going to
be using three ten fifteen B one one. Okay, And
for you earlier cycle folks, at three ten fifteen B one,
that's what you're going to be using when it comes
to the correction due to ambient temperature. Again, that's other
than thirty degrees celsius eighty six streets Fairney. Now, let's
talk a little bit about that table real quickly. So
if you look at three ten fifteen B one one,
you'll notice this table is broken down a little bit
into again columns. You'll have the big column on the
left that says ambient temperature, and you have a big
column on the right this is ambient temperature. One is
in fahrenheit, one is in celsius. Look at it's not complicated.
We typically conductors, it's whatever. On an exam, it's whichever
you want to use. But in the real world we
typically stick to fahrenheit because that's most of our thermometers
or temperature IR equipment, everything is is pretty much given
it to us in fahrenheit. But it doesn't really matter
because if you look at it, they're equivalent. Whether you
go across the line from left to right, it doesn't matter. Now,
one of the key takeaways that I want to talk
about is look at the middle column where it says
temperature ratings of conductor. Now, when you're implying applying this table,
it's based on the modifier that you're going to use
here is based on whatever the insulation is of the conductor.
It's not based on the opacity tables in three ten,
sixteen sixty seventy five. It's based on the conductor's insallation rating.
So for example, if I'm doing thajhen and I'm going
to be doing an adjustment of correction because i have
an elevated ambient temperature and so I'm a allowed to
use the ninety degree capacity to start my calculation. Then
when I come over here to find out what my
multiplier is going to be, I'm going to be under
the ninety degree column because that's what the insulation is
on my conductor. You get me. So that's where people
a lot of times will get lost. Now, if it
washwn for example, and I was doing an application where
it's in an environment, a wet location. It wasn't thhwn
dash too, but it was just thhwn. Then it only
has one h so that means it's seventy five. So
if I'm going to do a correction from an ambient
temperature other than thirty degrees salesia sagey six streets fareheit,
and I end up having to find what my multiplier is,
then when I come here, I'm going to be under
the seventy five degree column. I can't use the ninety
why because that insulation on that conductor is not rated
ninety in that environment, it's only rated seventy five. So
that's why I'm stuck to get my multiplier under the
seventy five degree column depending on what the ambient temperature
is based in fahrenheit or celsius. And that's why it's
so important folks on an exam that you have a
slide rule or a ruler or the edge of your
maybe your scratch paper to use to make sure that
you go cause these when you get into a stressful environment,
you can forget, you know, kind of get your lines
messed up and I want to make sure that you're
moving across the tables accurately. So give you a straight
edge or something with a straight line so you can
make sure you're in the right column, so you have
the right multiplier that you're going to be using. Okay,
now you'll notice that in the middle of this, you
see that one point zero zero for the sixty to
seventy five nine that's right in the middle. If you
go to the left, you'll notice how convenient that is,
twenty six to thirty degrees celsius, And if you go
to the right, it's seventy eight to eighty six, so
eighty six being the max based on the opacity of
three ten sixteen, it's thirty degrees celsius a sixteen fahrenheit.
That's why that the muliplier is one point zero zero,
So it's basically one for one. There is nothing that
changes if that's what you have, and if you had that,
you didn't even need to go here. Okay, but it
is right here, Okay, So anyway, that just kind of
wanted to point that out so that everybody is really familiar. Also,
if you look at the bottom, and I've had to
explain this to people what I told you earlier on
which tables of opacity go for which one of these?
You'll notice there's a note at the bottom, and the
note says that three ten fifteen B one one shall
be used for tables three ten sixteen and tables three
ten seventeen. Okay, you notice that, So that should answer that,
because again I still get an amazing amount of questions, but
it's right there in the note. Yet I still get,
probably at least once or twice a week, the question
on this on which table should I use? When it
was right there in front of you, And if you
fell into that trap, then you fall under reading comprehension
is use And that's why our fast Tracks program is
designed the way it is. It's a structured learning program
that walks you through these things to make you think,
because these aren't just exam stuff. This is real world
and you can get a conductor sized improperly, very quickly.
And so again I like to point out all these
little things because it really helps you understand the nuances
of the code. And these are notes, they're not informational notes. Okay,
there's a difference these notes. When you just see a
note under a table, it is very much applicable, or
I should say, applies very much to the rule. Whereas
if you see informational note, it doesn't apply. It's not enforceable.
It's just good information. It's a learning tool. It maybe
gives you some guidance. But when you see note under
tables or notes used in the code under a section,
it is very much still a code rule. In other words,
these notes apply to the code. It's not optional. Okay,
you get what I'm saying. Okay, all right, So let's
think of the structure of how we would flow through this.
Let's start with the order of matter. We start with
the ninety degree c apacity. That's what we would start with.
If the conductor is rated, the insulation is rated for
ninety Okay, we start with this and go okay, it's
rated for ninety right, and again we're not adding any
terminations in it right now. We'll let that be the
last step. But first things first, we start with the
ninety degree opacity. Now we apply the modifiers, whether it's
applied the adjustments if it's more than three current carry conductors,
or we apply the correction if the ambient temperature is
other than that's greater than or less than thirty degrees
celsius eighty sixtreets fahrenheit, and then we select a conductor
based on the seventy five degree column due to the termination. Okay,
so that's the easiest way to do it because basically
you just find the conductor under the ninety right and
then apply multiply by the modifiers, so it would be
ninety times whatever it be points seven zero for the adjustment,
and then another times another point seven zero, let's say
for the correction, depending on which one you're using from
the tables, and then you're gonna end it. You're gonna
get an end opacity. That end apacity is what you're
going to look under the seventy five degree column and
make sure one you've got a conductor that can handle
the load that's important, okay, and that you're not going
to have a load that exceeds the new calculated capacity.
But also you're not exceeding the limitations under the seventy
five degree column because that was the terminals. They're limited
to that. And this just keeps it simple. Now, one
other way you could do it is if you have
you could actually look at what load you have and
you say, look, I gotta have this load. This is
my load, this is my amps, this is what I need.
Now I need to see what size conductor I need
to have based on the fact that I've got adjustment
of corrections. So you start with your load that you
have to have, say fifty amps, and then you use
division and you go fifty amps divided by point seven
zero divided by point seven zero, and that's going to
give you an opacity value. Then you take that and
then you go to the ninety degree column and you
find a conductor that has equal to or greater than
that apacity that you just did. Then once you find that,
you can check your math by now using multiplication and
go the other way, and it should be greater than
or equal to the apacity that you need. It should
be more okay, or equal to. So there's two different
ways to do it. Now, if that is confusing for you,
do me a favor, because again, podcasts can be confusing,
and there's just different two ways to approach this. In
the real world, I say keep it simple unless you're
dealing with non metallic sheat cable. Uh, you know, if
you're just dealing with conductors and race ways, th hhn's
and things like that. Then automatically, whatever load you need,
go to the ninety. If you know you've got adjustment
of corrections, go to the ninety and then once you're there,
then you can apply your modifiers, multiply it by whatever
it comes from table three ten fifteen B one to one,
and then multiply again by whatever you get three ten
fifteen C one and that's going to be your in
that's your new apacity. Okay. Now you just go to
the seventy five degree column and pick a conductor that
can that equals equals are greater than that apacity, and
you're done because you really can't screw it up from there. Okay,
So anyway, that's the basis for it. Now, if you're
dealing with non metallic sheaf cable, for example, you're locked
into the sixty So even if you're going to choose
the ninety degree capacity and do adjustment and corrections from that,
and now you're going to have this miraculous new apacity,
you're still going to go to the columns. You're going
to still go to the sixty degree column and pick
the conductor that you need to handle your load. You're
just hoping that after adjustment of correction, that conductor is
equal to or greater than what load you need to
handle under column six, under the sixty degree column. Even
though it may come back as ten amps higher than
the sixty column, it doesn't matter. You don't get to
use those extra ten amps. You're just validating that your
conductor is still good under the sixty degree when you're
dealing with a non metallo chief cable. Okay, And again,
if that confuses you, and again podcasts and people say, well,
I can explain it much better. Well you do that. Okay.
It is a podcast, by the way, so I gotta
paint you that mental picture. But again, go watch Derating
Domstified if that confuses you, and you'll get it. Once
you get it, folks, you'll get it. Okay, All right,
let's look at example of a classic question and see
if we can't answer this question because there's other things
that we have to think about. Is what about current
carerent conductors. What about if they're continuous loads? What is
a continuous load? Well, the interesting thing about the National
Electrical Code is it's that gives you a definition of
a continuous load, and that is any loaded maximum output
for three hours or more. So a range, for example,
is never going to be a continuous load because the
loads always cycle. It's never going to be at its
maximum output. And we would never take a range, for example,
as a continuous load, even though you say, well, on Thanksgiving,
I'm going to cook a turkey for four hours. That
that's isn't that the range is on continuously for four hours. Yes,
but it's never at its maximum output. It's thermostatically controlled.
It's never going to be. It's cutting on, cutting off
to maintain a certain temperature. Okay, so it doesn't meet
the definition of a continuous load. Well, you may say, well,
what about a water heater. Well, a water heater by code,
it tells you that it's to be considered a continuous load,
whether or not your order heater in your house will
ever run for three hours at its maximum output regardless
of that, and chances are it never will because if
it has forty five hundred wide elements in it, there's
one in the top and one in the bottom. They
usually cycle out. So when the maximum output is never
both elements on it at the same time, it cycles out. However,
the National Electrical Code says, you know what, when you're
running a branch circuit for that water heater, I want
you to take that nameplate as a continuous load and
sizo conductors at one hundred and twenty five percent. I'm
just gonna tell you to do it. Then you just
do it. You don't read too much into it. You
don't say, well, wait a minute, that's not really a
continuous No, the code told you to take it at
one hundred and twenty five percent. So you just do
it and you size your conductors accordingly. But what's so
important for students is that you're gonna get exam questions.
Are you're gonna be real world situations where you you
may encounter something that is a continuous load, and on
an exam they'll usually tell you that it's a continuous load.
And if they tell you it's a continuous load, then hey,
ding ding ding ding ding, then it's a continuous load.
So it doesn't matter in your mind whether or not
this load is it maximum output. It doesn't matter because
they told you it was, so you take it as
face value. So let's look at a question. Example. A
classic question is what size THHHN copper conductor do you
need for a forty amp continuous load with seven current
carrying conductors in a EMT electrical metallic tubing. By the way,
EMT is a tubing. It's not a conduit. It is
a raceway, but it is not a conduit. I know,
I hate being picking on people, and because all of
us can make those little mistakes, I do it all
the time. But I do want to get people into
the understanding that it's a tubing, it's not a conduit.
And why is that important? Because there are specific conduit
rules that you can use conduits for certain things that
you couldn't use tubing four So it's important that you
understand the difference. And of course you guys are learning
the code. I mean, these are fundamental things that I
really want you to take away. Okay, but is it
big deal? And probably not. But again these are just
things that I figure i'll throw out there for you.
All right, let's start first. Let's do some first things.
Now we know it's a continuous load. So one of
the things we haven't looked at in the code is
the continuous load or rule for continuous loads and non
continuous loads. So for brand circuits, you're gonna be looking
at two ten nineteen A one, and for feeders, you're
gonna be looking at two fifteen dot two A one.
Now people say, well, why am I not looking at
two twenty five, because that's something different. That's for outdoor
branch circuits of feeders. It's still brand circuits under two ten,
and it's still feeders under to fifteen. Twenty five just
brings them together and gives you some additional rules for
when they're used outdoors. Okay, that's that's the only difference.
So if you have feeder rules in two fifteen and
you have brand circuit rules in two ten, then you're
looking at it and go okay. So two ten do
nineteen A one says I'm gonna take a continuous load,
and I'm gonna do it at one hundred and twenty
five percent. Okay, So we know it's forty ampiers and
we call it a continuous load. So I'm gonna take
those forty amps. I'm gonna multiply that by one point
twenty five, okay. Or if you get a calculator and
you do the one hundred and twenty five percent, my
calculator's funky because it's a scientific calculator. So I gotta
hit all these other damn buttons to do percentages. So
I just don't do it. So I go forty times
one point twenty five. And also I like to convert
all values. For example, one hundred and twenty five, you
move two spaces to the left from the right, and
that gives you the one point twenty five. To move
it back to an actual percentage, you move it two
spaces to the right. That's one twenty five. It's just
the way I do it. Same thing with eighty percent.
I start from the right and move it two spaces
to the left. That's point eight zero. That is your decimal.
That makes it easier to do your calculations, get everything
down into decimals. It makes the math easier. Okay, So
that's how I do it to one point two five.
So that's fifty ampiers. That's the minimum capacity required for
that conductor so far. Okay, so you know you're looking.
I go, okay, so I need a conductor that can
handle fifty ampiers. All right, So but we're not done. Now.
This is one thing that I will talk about that
really does screw people's minds up is how it's written
in two ten dot nineteen, and I really do. And
you're going to learn about this and derating demystified, but
I really want to focus on it and talk about
it real quick. When you look at two ten dot
nineteen A one, you have an A one and you
have an A two. Okay, A one is when it
talks about a continuous load at one hundred and twenty
five percent, and then it says a non continuous loads
at one hundred percent. Yes, you could have a brand circuit,
same as with a feeder that supplies more than just
one load in that collectively, you could have a load
on that branch circuit that is continuous, and you could
also have some other load element that's being supplied that
is non continuous. It's not as cut and dry as
this question is where it was just one load and
it was a continuous load. Okay, well that's easy. So
here's what it says under two ten dot nineteen A one,
And again this is exactly the same under two fifteen
dot two A one for feeders. So we'll just focus
on brand circuits. It says number one A one says
where a brand circuit applies continuous loads or any combination
of continuous and non continuous loads. It says the minimum
brand circuit conductor size. Okay, So it's not really about
the opacity yet, folks. It's about conductor size, the minimum
size that we have to have. It says the minimum
brand circuit conductor size shall have an apacity not less
than the non continuous load that's at one hundred percent
plus one hundred and twenty five percent of the continuous
load in accordance with three to ten dot fifteen. Okay.
Now we have an exception for that, okay. And this
is where the assembly where all of the everything is
rated at one hundred percent, and then you don't have
to take a continuous load at a hundred and twenty
five percent, you just take it at one hundred percent.
That's because all of the components are rated at one
hundred percent. That's typically not what you're going to see
on standard molded case circuit breakers are usually going to
be limited to eighty percent, and eighty is the reciprocal
of one twenty five. Okay, so there is an exception
for that. But again, unless you get devices breakers that
are rated for one hundred percent that take this into
consideration for continuous loading, then the normal thing that you're
gonna get is going to be limited to the eighty percent. Okay,
all right. So and again you're looking for the word
eighty in the code, and you're not gonna find it
because eighty is the reciprocal of one twenty five. And
you say, what does that mean? What does this reciprocal mean? Well,
what it means is if I take the one hundred amps, right,
and I multiply one hundred amps times point eight zero, okay,
then that would be eighty amps. But if I take
eighty amps and I multiply by one point twenty five,
that's one hundred amps. So they mean the same. They're reciprocal,
but you use them differently depending on what's given to you.
If like, like, if they already give me the apacity
of the of the uh, whatever the load would be,
then I can use multiplication and do that times one
hundred and twenty five percent, and then I search for
the conductor, and I've already got a conductor that takes
into consideration that that continuous loading. Whereas if I have
a breaker and I want to know what the limit
is of the continuous load on as breaker knowing that
breaker is limited to eighty percent. Then I can take
the rating of the breaker and multiply that by point
eight zero, and now I can find out what the
apacity is that I can't exceed. That's going to get
terminated on that breaker and not exceed the rating of
that device which is limited to eighty percent. So you
understand that's what reciprocal means. Okay. So you're never going
to see the word eighty percent limiting breaker to eighty percent,
but you're going to see the one twenty five. You
just need to understand what reciprocal means and what we're
talking about here. So don't go hunting for this eighty
percent magic thing in the code. You've got to understand
how it works. Okay. Now, so that is the first one.
That's a one. But here's what people forget about. There's
also an A two. Okay, and A two says okay,
if all I had was a continuous load, for example,
and there was no adjustment or correction involved. In other words,
we're in that perfect world. Remember thirty degrees salesius eighty
six streets fairaheh. We don't have more than three current conductors.
A perfect world, Happy, happy it's a perfect world, then
I would just stick with this and size that conductor
based one hundred and twenty five percent for the continuous load,
and size my conductor accordingly, and I'd be good to go. However,
when you do have some type of adjustment or correction involved,
like we do in our example, now you have to
look at A two and A two says okay, well,
the minimum brand circuit conductor size shall have an opacity
not less than the maximum load to be served. Okay,
after the application of any adjustment or correction factors in
accordance with three to ten dot fifteen. So this is
after it's served. So what does that mean? Okay, Well,
remember what we said we had a forty amp continuous load.
That may be what the actual load is. It's forty amps.
We're just calling it a continuous load, but the real
load is what forty amps. I mean, that piece of
equipment may have a name plate. That name plate may
say it's forty amps just because we're telling it to
be taken as a tenuous loads. We're only doing that
because of breaker and conductor sizing. The load is still
the load, even though it's still forty amps and we're
sizing a conductor bigger, or we're sizing the breaker based
on the limitation, it's still forty amps and that's what
it means. That's the load to be served, and we
have to make sure that the conductor is at least
size to handle that load, even after we apply any
adjustment or corrections. Now we learned earlier how to apply
those adjustment and corrections, right, But this is saying, at
the end of the day, the conductor for this brand
circuit is going to be at least this size, do
you like it or not, And it's going to be
whichever one of these yield the largest outcome of conductor size.
So if the conductor size, for example, was based on
A one, which is one hundred and twenty five percent,
and you picked a conductor based on this case, we
said it was a fifty amps. If you do it
based on a two, and you do it based on
an adjustment of corrections, if it yields a conductor that's
smaller than the eight, then you're still going to go
with the eight because you have to go with whichever
one yields the larger conductor requirement. You're with me, Okay,
I just want to make sure we understand that now. Also, Conversely,
if I have a situation where there isn't any continuous
loads involved, there's just none continuous loads, then I might
not even have to look at A one at all,
because I'm not going to be applying any one twenty five.
We're taking the load at the load, which is again
non continuous loads at one hundred percent. But yet I
still may have to apply to ten dot nineteen A
two because I do have adjustment and corrections and I
still need to make sure that the conductor's size and
its subsequent opacity is equal to or greater, okay, to
the maximum load that's being served. After I do the
adjustment and corrective math, it makes sense. Hey, folks, I
told you this is probably fundamentally one of the hardest
aspects for people to understand within the National Electrical Code.
It really is. Okay, so let's look at go back
to our question, and I'll reiterate the question again. What
size thhchan and copper conductor do you need for a
forty amp continuous load with seven current can conductors in
an EMT? Okay, so we did start first, we said
forty amps times one hundred and twenty five percent. That's
fifty amps. Okay, so we know the amps based on
A one. We got it that far. Step two was okay,
we had seven current carent conductors, so we need to
think what is our multiplier. So we're gonna go to
table three ten fifteen C one and we'll notice that
since we have seven current care and conductors, we're going
to be at the seventy percent adjustment factor. Okay, because
we have seven to nine current carent conductors. In fact,
our question had seven, so we're gonna use seventy. Now
we want to convert it to decimals, so we go
from the right side of the seventy and move it
two spaces to the left. So now it's point seven zero,
So that is your your multiplier. Okay, that would be
the multiplier that we're using. Okay, Now we'll do the math.
We'll do the math both ways and see what it
what's conductor sizes would be here, okay, So first things first,
let's just make it easy for us and just do
it one hundred and twenty five percent when first and
see where we're at with that. So that was going
to be a fifty AM, so first thing I would
do is just to check this. I would go to
a ninety degree C column in for thhhn. Okay, because
it didn't say it was in a wet and said
it was THJGN. I'm not gonna read anymore into this,
or we're assuming that wet locations and that didn't come
into the equation. Okay. I'm just going to answer what
I'm being given. That's it, just what I got. That's it, Okay,
don't overthink it. Don't say, well, it doesn't tell you
what the terminals are. Look, this question doesn't even say
how it's terminated. So I'm just going to answer the question.
It's only asking me the conductor I need for this
now in reality, in real world reality, that the terminals
are going to be seventy five, the conductors at least
seventy five. So again in one ten fourteen A one
C I believe, or A one or C one A whatever.
If you look in there, you'll see that the option
is look, even if it's under one hundred amps, that
I can skip the sixty as long as the wires
at least rated seventy five. If the terminals are rated
at least seventy five. If everything's rated seventy five, boom,
boom boom, I'm good to go. Okay, be careful in
your exam prep because this is a real world question.
But be careful because they're not telling me anything about
the terminations, so I'm not gonna I have to be
very cognizant of people. Say, well, God, Paul, which do
I use well? In some exams they may want you
to assume that they didn't tell you what the terminals are,
and you're gonna be limited to the sixty degree column, right,
you have to be very cognizant of that, be very
you don't really have to pay attention to that. But
I can't tell you that in a question like that,
I can't think for what the test center does. I
don't you know. I can't get into the mind of
the people that write the test for every state. But
the chances are you have a higher probability of being
successful if you don't read more into it than it is.
So in this case, I'm not worrying about the terminals.
I'm just using what they ask me. That's it. And
what I do know is I've got seven current can conductors.
I got forty amps of continuous load and it's thhn
and it's copper. That's it. Just answer what they give you, Okay.
For the vast majority of the time, you're going to
be Okay. I just want to remind you that in
the real world, you have other limitations that you need
to be very cognizant of, Okay, and that is your
limitations and one ten point fourteen based on whatever the
temperature limitations and terminal limitations are that you're terminating at.
Just keep that in mind, Okay. Let that float around
in your mind so that you're at least prepared for it. Okay. Again,
I can't get into the mind of the test taker,
so you know, of the the person that writes the
exam question whether or not they went that deep or
they intended you. There's no andardization for this, so it
could go anywhere. Just understanding your mind that those are there,
and maybe even look at those options for your answers
and see if that is even one of the options.
If it's not, then you know they didn't go there. Okay.
It's the best I can do for you. I'm just
trying to give you all of the things to think
about here okay, but again, this episode is not so
much exam prep as real world scenarios. All right, So
if we're doing the math, let's see here. So if
I were to go look right now and say, okay,
first things first, if I have to pick a conductor
that is under the sixty it's give me. Gonna give
me fifty ampiers under the ninety degree column. First off, okay,
that I need at least fifty ampires. We started out
with that. We took the forty amps at one hundred
and twenty five percent. That's what we started out. We
haven't even we haven't even worked in the seventy percent
adjustment factor yet. So let me get my codebook and
we'll go with you. And I'm gonna go down and
we're gonna go three, ten, sixteen, and we're gonna look
under the seventy five degree column. And let's see here,
so I need to do so it looks like an
eight gauge is good for fifty five amps under the
ninety degree column. You know, the ten gauge is not
gonna work. That's forty. So at least looks like it's eight.
And of course a six gauge is good for seventy five. Okay,
so I'm starting there right, Let's say, okay, you know,
at this point it looks like it could be eight
or six, but that's just we haven't even applied any
of the adjustment yet. Remember what I said, just pick
your conductor from the ninety I'm trying to make it
as simple as possible. Let's move forward, all right. Now,
let's do that fifty five amps under the eight gauge,
and let's do that and multiply that by the modifier
point seven zero, and that is fifty five amps. You've
got your calculator, do it with me times point seven zero,
that is thirty eight point five. Is that gonna work?
Absolutely not, because remember what it said in two ten
nineteen A one two that after after the adjustment, I
still have to handle the load. And what was the load?
It was forty amps? That was the load, right you
with me in this question. So in that scenario, it
looks like, okay, well, an eight would be too small,
So what about that six? Well, the six is good
for seventy five amps. So I take that seventy five,
multiply that by point seven zero, and that is good
for fifty two point five amps. That meets the rule.
That's perfectly fine. Now let's double check this again. Under
the seventy five degree column, that six gauge that we
just looked at is good for sixty five amps, okay,
But we also look under the eight gauge and it
says fifty amps. But that's been rejected. Why because of
the adjustment we have to make. Because the conductor both
falls below that fifty amps, it ends up dropping down
to thirty eight point five. So that's not gonna work.
You see how that works. So even though under the
seventy five it set is good for fifty, that no
longer applies because we had to do an adjustment of
correction and the actual ampacity now of the conductors reduced
below that fifty for the eight gauge. So it's not
gonna work for us. Okay. Now, in a perfect world
it would work. If we had no adjustment or corrections,
then it may work, but it's not gonna work for
us now, okay, because we were using two ten dot
nineteen A two okay. All right, So now the answer
for us is the sixth gauge. Okay. Now let's check
that because we did say ours had a continuous load. Right,
So what if we went the other way and said, well,
I want to compare this to taking it a one
hundred and twenty five percent and see what conductor it yields.
So watch this, so remember you're comparing this to two
ten nine nineteen eighty one. Now we did the A two,
we're doing A one. We're gonna just we're gonna use
the the continuous loading compare and see if that yields
a larger conductor. So that would be the Again, we
did it forty times one point twenty five. That is
fifty amps. Now we don't use the ninety here because
we're not doing adjustment corrections. We use the cut seventy
five degree column and we go straight to the seventy five.
So when we did that, we're looking for a fifty
AM conductor and that would take us to an eight gauge.
And you're thinking, dude, I can use a gauge because
A one says that. Remember you got to take whichever
one yields the larger. So in this case, the eight
under that allowance would not be the larger conductor when
you're comparing a one versus A two. Because I do
have some corrections that I have to take play or
adjustments that I have to take place. Then guess what
A two yielded the larger conductor. That's why we went
with it. You see how that works. You have to
compare a one to a two based on what criteria
you're given. Okay, hopefully that makes sense to you. Hopefully
it does. Now that was for the number of conductors.
Let's do another little one. What if we wanted to
do it based on the ambient temperature. Now I get it,
there's so many of you out there who don't even
take ambient into consideration, but we're going to do it today.
So let's say you have conductors running through an attic
that hits forty five degrees C. Okay, So let's say
we're in a raceway. They're running through the attic in
a raceway. They're in Chicago and they're running EMT through
a raceway through an attic. Okay, So it hits forty
five degrees C in that act, or one hundred and
thirteen degrees fahir Nheit. Well, obviously the ambient temperature to
which that raceway runs through or or tubing in this case,
if it was EMT tubing, but is a raceway. But
it's not a conduit. Again, just reiterating that fact. But
it's still tubing. It is still a raceway. The opacity
of those conductors are going to change. Now in this example,
we don't have more than three current carent conductors. All
we're gonna worry about is the ambient. Make our life simple.
So we have THHHN copper. We have three current current conductors,
so we're well within the three ten sixteen of the
three current carr And conductors or less. So we're good there.
And it's a thirty amp load. Now, the load didn't
say anything about this being a continuous load. It just
said thirty amp load. That is it. Okay? Now, first
things first, the load is thirty amps, so I'm gonna
start with thirty amps, and I need a conductor that's
going to be equal to or greater than thirty amps
after the correction. Now, did you notice something I did do?
I didn't go to two ten dot nineteen a one
because it didn't say anything about it being a continuous load.
So the only one that comes into play for me
is two ten dot nineteen a two. Because there is
going to be an ambient correction that needs to take
place here because I'm going through an ambient temperature that's
not thirty degrees celsius eighty six degrees fahrenheit. It's elevated.
There's heat there. So not only do you have the
heat from the attic, but you have the mutual contribution
from the heat from the conductors under loading. That's going
to rapidly get that temperature rising up to the volatility
level of that insulation and it could cause it to
melt down. So how do we counteract that. We reduce
the amount of current that can go through the conductor
to try to keep it from getting to that volatile
temperature level of the insulation so it doesn't start breaking down.
That's why we do this. Okay, That's why we're playing
with these amps because amps rate heat. Okay, so that's
what we're trying to do. Okay, Now there's somebody out
there to say, William An Amstom generate heat resistance is
Look what we're saying it is. The more current you
pully is going to generate more heat in a mutual
environment under loading, and so we have to do something
to reduce that loading. And that's what we're trying to
do here. We're's certainly not going to reduce the ambient
temperature because that's the attic. It is what it is. Okay.
Now some people ask me, that says Paul, how do
you get these values in an attic? You know, it's
for an exam for example. They got to tell you
these things in the real world. It's it's really hard.
But most of the time I tell people for attics,
you know, can you can equate If you're gonna have
a lot of stuff running through attic and thermal insulation
and things like that, then you can add anywhere between
fifteen to twenty degrees for the for the temperature or
the ambient up there, although it could go much much
higher than that. So there is no you know, you
got to use your own rule. I can't tell you
what to use addicts and different environments. Now, if you're
running through a boiler room, for example, then you can
get a good baseline of that room and kind of
get an understanding from the engineers design professionals with the
temperature's lebel to be in a room. You can get
some extra values on that, but you're just gonna have
to use your judgment. So on an exam that going
to tell you because they got to tell you in
the real world. I think the reason most people don't
put an ambient correction in is because they don't know.
And if it's in the walls, in a conditioned space
inside the building envelope, and it's an attic that is
exhausted or temperature controlled, then you wouldn't None of this
would even come into play when it comes to the ambient.
But every conditions different and I just want you to
be aware of that. And it does play a role
on the conductor's opacity. Okay, so we started with thirty
an peers. I need a conductor that's at least equal
to or greater after we do the correction, because that's
what it said in ten nineteen A two. That's what
it said. So thirty amps is my load. Now I
need to find the correction factor first. Here, let's go
on and do that. We'll do this first. So we're
gonna go to table three ten fifteen B one. Now,
remember our insulation is THGN, so we're gonna go under
the ninety degree column. Again. That's why we're doing it.
It's because not because of the ambient. It's because of
the insulation rating of the conductor that we're using. So
in our case, it's ninety degree rated at THHGN so
and we're using the since we're talking celsius, we're gonna
use the left side celsius and we're going under the
ninety and since we were talking about forty five C,
we go down list here to forty five C and
we're looking for the modifier. Is what is the modifier
that we're going to use, and so it's one hundred
and thirteen degrees fahrenheit. So we're gonna go down and
you'll see that that is going to be let's see,
one hundred and thirteen degrees fahrenheit is going to be
point eight seven, Okay. Point eight seven is going to
be our modifier for that. Okay, so we write that down.
You got your point eight seven. Okay, Now let's see.
So let's let's see how we'd apply that. Right, So
let's let's continue, Let's do some let's do some work here. Okay.
So if I'm dealing with the ninety degree C, the
first thing I need to do. Okay, now let's go home.
Since I am going to be doing a correction. I
now know that I can use the ninety degree for
adjustment and corrective purposes on this thjgen. So I'm gonna
go to the capacity table first. Remember we got all
our numbers. Now I'll go three ten, sixteen. And the
reason I'm gonna I'm gonna go to ninety because we
are making an adjustment in correction. So the code tells
me I can do that. Under three ten to fifteen
says I can do it. So I'm gonna go down
and I'm looking for the titchen, and I want to
see what am I gonna be first to make sure
that I can handle the thirty amps? All right, So
I'm gonna go down and let's see. Okay, So it
looks like I've got some options here at thirty ams, okay,
except be equal to or greater than thirty ams. Now
you already know without doing anything extra. You should know
that if I've got to have a conductor after adjustment
of correction that's good for thirty amps, then there's no
way that I can start my calculation at thirty ams.
So it should be a no brainer that even though
a twelve gauge under the ninety degree column is good
for thirty ams. You're certainly not gonna start there because
you know that you're gonna have to make an ambient correction.
So whatever you do, it's gonna drop below thirty. So
you shouldn't even waste your time. You know, it can't
be a twelve gauge. And then we're not even talking
about small conductor rules and overcurrent protection. We're just we're
just talking coals here, We're just talking conductor of the opacity.
But that should be the reason you realize it, dude,
I don't even need to start there, even though it
says thirty Remember it's got to be thirty ams after
the adjustment of correction. Okay, so there's no reason to
start there. So logically you're gonna start. If you're gonna
do the math, you're going to start at the ten gage,
which is good for forty ampiers under the ninety degree column.
So remember our multipliers point eight seven. So we're gonna
use multiplication now because we're starting from the ninety capacity
and we're moving down. Okay, so we do forty times
point eight seven. Remember, converted into decimals eighty seven percent.
Start from the right, move to decimal places to the
left point eight seven, and that is thirty four point
eight ampiers, which is okay after this, after this corre
ambient correction, do I have a conductor that is okay
for use? Okay at a thirty amp load? Absolutely? What
about an eight gauge? Well, the eight gauge you're sitting
and going, okay, Well, do I need to go any further? Well, obviously,
if the forty amp was good, the eight is fifty
five amps under the ninety, then you already know that
that's okay. It's more than enough. One of the key
takeaways that I also want to point out is that
you still cannot even though we got thirty four point
eight amps, if you take forty amps and multiply that
by point eighty seven, you can't use that thirty four
point eight amps. Okay. I just want to make that clear.
You are still stuck to the seventy five degree column.
You're just doing an adjustment or correction to find out
ultimately what the conductor's opacity is, so that you want
to make sure it still has apacity. You need to
handle the load without exceeding the terminal limitations under the
seventy five degree column. Okay, because that's what we told
you that, that's what the lugs are. That's you know,
that's what we're using, right, So that's how it works.
So now that that ten gauge is now good for
thirty four point eight amps, but if you look underneath
the seventy five degree column, it says the maximum it's
good for thirty five amps. So it's still good even
though after it's only thirty four point eight amps. We're
not using that thirty four to eight point eight amps,
and we're no certainly not using that thirty five amps.
We're just making sure that we have a conductor that
can handle the load. Right, so we know that that
ten gauge can handle the load. Now I don't even
need to do that for the A gauge because that's
a no brainer. Now, how can you quantify this? How
can you check this? Well, one of the things you
can actually do now is okay, so now under the
seventy five degree column for that ten, take that thirty
five amps it's there, and do thirty five and they'll
divide that by point eight seven and that gives you
forty point two zero. Drop the point two zero. That's
forty amps. And you just go to the right and
you see that that equates to the actual forty degree
for this example. It just you're just quantifying it. Okay. Now,
let's kind of look at that. So if I use
the twelve for example, because you say it's thirty, after
that point eighty seven is a multiplier is added, then
it gives us like a twenty six point one amp.
So that's below. So that's why you can't use a twelve,
even though you look at it and you say, well,
ninety degree, it says it's thirty amps. But no, that's
not how it works. Now one of the last steps,
and in this example, we will kick in and show
you how we would apply one ten dot fourteen C. Okay.
Now we're gonna check the terminals. Now we already told
you there's seventy five degree, okay, but we would do
that by going to one ten dot fourteenth C. Okay.
So when we go there, we must still respect that
seventy five degree. See temperature rating or terminal rating okay
for typical equipment one hundred amps and under unless it's
marked otherwise. So if it wasn't marked or didn't have marks,
and obviously you didn't know the terminal ratings in the
real world, then you're going to be limited to the
sixty degree column, and you do exactly the same thing
we did. It's just you're going to be limited. You
can't exceed the values under the sixty degree column. So
in our case, let's just be craps and giggles and
say that we were limited by the sixty for whatever reason,
and we just determined that we needed a ten that
if you go under the sixty degree column, you'll see
that the ten is good for thirty amps even under
the sixty so the adjustment of correction took place from
the forty. After the adjustment of correction, it's it's still
good for thirty four point eight amps, but the limitation
is thirty amps under the sixty three column. And guess
what our load is. Our load was we needed at
least thirty amps, So a ten gauge would still work. Okay,
does that make sense? Okay, just wanted to throw that
little extra in there for those that say, well, what
about if sixty degree applied and I didn't know what
the terminal in this case, your ten would still be okay? Okay?
So takeaways takeaways a lot of folks will look at
the ninety degree columns, see the twelve tchn at thirty
amps and think perfect, that's a thirty amp load, thirty
amp wire. I'm good to go, But that would be
wrong because of the conditions of use. Okay, And I
just we want to make sure that people understand that
when they take all of that that away, and that's
why it's so important to learn all of these aspects
right for calculating things.
Speaker 1: Right.
Speaker 2: Okay, let's let's let's look at a couple more because
I don't again and I want to make sure that
I cover as much as I can. Let's see, so
we have some what's called opacity traps on exams, okay,
for talking exams, some traps that you might run into.
So trap one, use ninety degree capacity for the final answer. No,
you only will use the ninety for the math. When
you're selecting a conductor, it's going to be based on
the seventy five or sixty depending on the limitations. Okay.
And they typically will tell you the terminal ratings and
everything that you need for the question. Because I think
most boards that write exams, or most committees, you might
think they're trying to trick you, and not all of
them are created equal. But they don't really like ambiguous stuff, right.
They try to answer the ques questions, give you as
much information as you can. Okay, So I just remember
that the ninety. Unless it tells you that the terminals
are rated for ninety, then you're never going to use
the ninety except for adjustment and corrective purposes. The end result,
you're going to select a conductor based on seventy five
or six degree column. Okay. Trap number two forgetting the
multiple multiply continuous load at one hundred and twenty five percent,
there's certain areas in the code that tell you to
just take it as a continuous load or just to
apply one hundred and twenty five percent just across the board.
And then there's other things that they may say. In
a question that says forty amps of continuous load, then
you need to know that I take that forty amps
times one hundred and twenty five percent, ultimately remembering that
the forty amps is the actual load. Just because I
took the forty amps at one hundred and twenty five percent,
that's not the new load. That is the value you
use for a sizing conductors and breakers. That is not
the actual load. The actual load was the forty amps
that you started out with. That's an important thing for
you to lock in your brain. Just because we call
it a continuous load doesn't change the actual load. It
is what it is. Okay, trap number three. Okay, counting
equipment ground and conductors as current caring conductors, they do
not count. So when you're doing counting current care conductors
and you're trying to do apply this adjustment factors, don't
count equipment grounds. I know that should sound like a
no brainer, but just don't do it. Also, neutrals don't
always assume that the neutral is always current carring. If
the neutral only carries the unbalanced current of a multi
wire or a three phase system that is balanced and
you don't have a neutral, then you don't count it. Now,
if it is a four wire three phase y system
with harmonics things like that, then you're going to or
if you're taking a two phases from a four making
a three wire system from a four wire three phase
and creating a single phase two phase with a neutral,
then you have neutral current that you have to calculate
in and that would be a current carr And conductor.
If you have high levels of non linear loads, then
you're going to have a current carrying conductor. Okay, so
typical three phase four wire y systems with linear loads,
then that neutral is going to count, don't forget, so
read the question. But if it's a neutral and all
it's carrying is the unbalanced current from let's say a
again a multi wire brand circuit then or a three
phase delta system, let's say with a neutral. If you
have one, then it's going to be balanced out. Then
you might you might not have a neutral load, so
it wouldn't be counted as a current carrying conductor. So
important to read the question and understand whether or not
you're counting a neutral conductor as a current carr and conductor.
It can really throw off your math if they slide
one in there. Okay, that's something to keep in mind.
Another trap that people fall into is doing your adjustment
and corrections from the seventy five degree column instead of
the ninety. Now, remember the only time you can do
your d rating or adjustment and correction from the ninety
is when your insulation truly is rated ninety degrees c. Okay,
if you're using you're doing an adjustment of correction, and
you're in an environment which you're using say THHWN, then
that's seventy five degrees. So you're going to do your
adjustment and corrections from the seventy five because of your
limitation of the insulation's rating. But if you're in a
dry environment and you're using THHWN, which is also usually
mutually THHHN, then in a dry environment, you're going to
be doing this from the nineties where you're going to
start your d rating. So read the question closely and
again this is also real world scenarios. Pay attention from
where you start your adjustment corrections from could you make
a big difference? Okay. Another trap that you want to
steer clear of is if they ask you a question,
for example about non metallic sheath cable. Now, I can
use the ninety degree see opacity value under three fourteen
dot at three thirty four dot eighty, but ultimately you're
still going to be limited to the sixty degree no
matter what. The only reason we're using the ninety is
to adjust and correct it to make sure one we
still have a conductor can handle the load, and as
long as that load does not exceed the value that's
under the sixty degree column. So we still have a
conductor that's equal to or greater than what's under the
sixty degree and the fact that our load does not
exceed the sixty degree columns value. That's all we're really doing, Okay,
So keep that in mind. Don't don't fall for those
little traps that type of thing, and never use the
ninety degree for your end value. In fact, with that one,
I always tell people, just go to the sixty right away,
pick the conductor size you need. If it's not metallic,
sheats cable, just pick it right away under the sixty degree,
and then do the math to make sure you're still okay. Okay,
all right, let's mix a few questions and let's see
if we can answer a few of these. A few
of these questions here, let me give you one real
quick to take away, and you can pause this podcast
if you want and work it offline. Let's say I
have fifty five amps of continuous load is fed in
a through a race way, and I have six current
carring thhn conductors running through an attic at forty degree
C in the terminals, or seventy five degrees see rated. Okay,
what size conductor is required? Okay, so in this case
we know it's fifty five amps and it's continuous load.
It tells us that I don't need to know how
long the load runs because the question tells me it's
a continuous load. Okay, Now, fifty five amps is the
actual load, right, I mean that is the load. But
when I see a continuous load, that means, okay, I'm
gonna have to do something. I gotta do something else
because I gotta make sure I've got fifty five ams,
and because I'm gonna have to because there is a
continuous load, I'm now gonna have to compare two ten
nineteen A one to two ten nine nineteen A two,
and I'm gonna have whichever yields a larger conductor. That's
what I'm gonna go with. But I also understand, but
I have a correction, and I have an adjustment. I'm
gonna be honest with you, folks. This is about as
complicated as they really do get on an exam. This
is a three like a three step calculation question, and
so it's it's not hard, but you have to think
about it in steps and when I tell you to
dissect things, that's exactly what I mean. Okay, So fifty
five amps, that's my load. Period, write that down. That's
your load. Fifty five amps is a continuous load. Before
I even apply any adjustment of corrections, I need to
find out what would two ten dot nineteen a one be?
What conductor would I need? First? Okay? And seventy five
degree terminals? I get all that. It's thhhn. I get
all that. So fifty five times one point twenty five
and that is sixty eight point seventy five ampires first, okay.
So if I were to use that first right, and
I would go to the seventy five degree column because
I'm not using the ninety right because I'm not doing
adjustment of correction. I'm just doing the two to ten
dot nineteen eight one. I'm just dealing with the continuous
load to see what conductor I would need. So in
that one, I'm gonna look down under the seventy five
because that's what our terminals are. And remember, don't fall
for that. In a real world, if you didn't know
what the terminals were, then you would be locked under
the sixty. But I'm telling you they're seventy five. Okay,
So I'm going under seventy five, and I'm gonna say, okay,
I need a conductor that's good for sixty eight point
seventy five AMS. So it looks to me that it
would be a four gauge. Let's see, yep, because I
need sixty eight point seventy five. The next one that's
eighty five ams, So it looks like a four gauge.
So just write that down. Really, that's all you gotta do.
Write that down. So four gauge copper. Okay, all right. Next,
let me go in and find my multipliers. Now, since
i've got six current carent conductors, I'm gonna go to
three ten fifteen C one, and it looks like from
four to six it's an eighty percent multiplier. So I'm
gonna turn that into decimals. So I'm start from the right,
move it two spaces to the left, so it's point
eight zero. Okay, I'm writing that down. So that's my multiplier,
point eight zero, gotcha. Next, let's get that ambient correction value. Well,
we're gonna go to table three ten fifteen B one.
We're gonna be in the ninety degree column because it
is thhhn. And that multiplier I believe is point nine
to one. So let's double check. And I didn't that
from memory, but let's let's go never trust it, go
look at it. I'm gonna go look at it. So
since our temperature is forty degree C, we're in the
left column and we're gonna find forty degrees c there.
It is right there, and we're gonna go to the
right and that is point nine to one. So that
is correct. We're at point nine to one is my multiplier. Okay,
so we've got the point nine to one that's for
the ambient correction, and for the adjustment, we've got the
point eight zero boom. Okay, now remember what it said.
At this point, I already know what I need for
the continuous load. I know that the four gauge would
handle that part, but I need to see if that
ends up being the largest conductor. So now I'm gonna
go using a two. I'm gonna say, okay, remember, I'm
gonna go to the ninety Okay, I'm gonna go to
the ninety column and I we'll say, okay, and what
do I need to do in order to see what
size I need for this. Okay, Well, let's go to
the right, and I'm gonna show you are shortcutting a
long way to do this and another way to do this,
but well, let's just go this way. So I'm gonna say,
since I'm starting with the four and I know it
can't be, it's got to at least be a four
because that's what the continuous load one. So I'm gonna
start with the four. So I'm gonna go to the four, okay,
And let's go to three ten sixteen. And the reason
I went to the four gage is because we already
did it for continuous load, and we know that it
can't be smaller than a four because that was the
first one we did for continuous load. So it's got
to be at least a four. We're trying to see
if this one requires it to be larger than that. Okay,
So I'm going here and I'm at three ten sixteen,
I'm gonna go to a four, and a four looks
like it's ninety five amps, Okay, So I'm gonna come
back and I go, okay, well, i'm gonna do the
ninety five amps and I'm going to now do the
mass that I had before. I'm gonna do it times
point eight zero in times point nine to one. So
I'm going to take that ninety five, multiply it by
point eight zero, multiply that by point nine to one,
and that equals sixty nine point sixteen AMPS. Now the
key here is that we knew that the fore gauge
was what's required when it was a continuous load, and
all we're doing here is to verify that we still
have a conductor after an adjustment of correction that's still
going to give us a value that it's equal to
or greater than what that was the fifty five ams
So obviously sixty nine point sixteen amps is fine, it's
not not a problem. Now you can also do this
as well using the fifteen one. Let me show you
how you can do this another way. You can actually
use the fifty five ams right that you need to
have after the adjustment of correction, So you can do
the fifty five and do division. Do fifty five divided
by point eight zero divided by zero point nine to
one and equals seventy five point seventy four. So if
that's the case, then you will go under. You go
back to the to the code book under three ten, sixteen,
and go to four again and look to the right,
and you'll see that under the ninety good for ninety five, okay,
so it's under the fourth, it's ninety five. So it
tells you that it's obviously equates, and it works backwards
and forwards. So whether you started and if you were
doing it this way and you started at the fifty
five and you use a vision, you would be going
here and you have to find a conductor that's at
least rated for the seventy five amps seventy five point five. Well,
you couldn't go under the four, right, because previously it
said it couldn't be smaller than it at least to
be a four, So you couldn't go to a six,
even though that says seventy five. But the fact that
it is point five, you don't drop point five, okay,
So it's over seventy five amps, so that immediately would
push you up into a four as well. So that's
why you would be at the ninety five amp rated
conductor under the ninety degree column. So either way, it
shows you how to do that. But the reason we
started with four is because we knew the conductor couldn't
be smaller than a four, because that's what it was
in our first equation to ten to nineteen eighty one.
All we're doing now is to validate that and check
it now to see if the conductor size changed after
adjustment and corrective purposes, because we have to go with
whatever the larger is of the two, right, So that's
important for people to realize. You have to compare and
see how that works. Okay, all right, so kind of
a wrap up here. Final words, Always use the ninety
column when you're doing the de rating as long as
the installation of the conductors rated for that, but always
select your final conductor from the seventy five or sixty
degree depending on the limitations in one ten dot fourteen
c or whatever wiring method you're working with, like non
mentallity tith cable. You can use ninety, but ultimately you're
gonna be stuck in the sixty. Remember continuous loads, whether
they tell you in a question or you're in the
real world and somebody says, hey, this is continuous load,
then you're taking that load at one hundred and twenty
five percent for conductor sizing and breker sizing. But that's
not the actual load. The actual load is the value
that you're given. Okay, so forty amps a continuous load
is still forty amps. Yes, you're going to add one
hundred and twenty five percent to it, do it multiply
by one hundred and twenty five percent for conductor sizing
and for breaker. But if you ask what the actual
load is, it's still the forty amps that didn't change.
A neutral may or may not be considered a current
car and conductor, depending on what type of system it is.
So be very diligent in your questions. In a real world,
you'll know that based on the system and what the
circuits are. Never ever apply a temperature correction to the
seventy five degree column unless you're using a conductor that
is rated seventy five degrees C in an environment for
that and you'll be using it from the seventy five
because the insulation's not rated ninety. So that's when you
would use the seventy five. But if you're in a
dry environment, you're using something like a THGN or a
thhwn DASH two that's what that dash too means treated
as a ninety degree rated insulation, then you use the
ninety to do your adjustment and corrections, so you may
use the seventy five, but it is usually when you're
only dealing with an insulation that's rated seventy five, because
you can't use a ninety if the insulation's not rated ninety.
You understand that always follow this order. Determine your load,
find your opacity under the ninety, do your adjustment of corrections,
and then validate your temperature ratings by making sure that
it doesn't exceed and that you're seventy five, five or
six degree column is going to be enough to handle
the load. And so we always referring back to these one,
ten dot fourteen terminal limitations. And if that any of
that confuses you, please do me a favor go over
to fast tracks tube and search for de rating Demystified.
Whether it's version two point zero or three point zero,
it's still going to give you those real important factors
to remember, because this is probably the most confusing topic
for people who are working through the National Electrical Code.
And my hope is that I didn't make it more
confusing for you. Till next time, folks, stay safe, God blessed,
we'll catch you in a Future podcast.
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