Speaker 1: What's up, everybody.
Speaker 2: Welcome to another episode of Let's Ask Paul, the podcast
where you get to ask me, Paul Abernathy, anything you
want about the National Electrical Code and all things electrically related,
and I will give you my opinion. You can agree
to disagree, but at the end of the day, it's
my opinion. I own it and I will give that
opinion to you. If you would like to send for
an opinion to NFPA, you're free to do that. It
carries no more weight than mine. But I am giving
you my thoughts and my insights on different things that
are asked of me here at PAULA Abernathy dot com.
So that is the portal where you can submit questions.
Just go to Paul Abernathy dot com and you'll see
a pretty simple format for you to be able to
ask questions.
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Speaker 2: Just go there and feel free to ask questions. A
couple announcements that I'm going to make in the Let's
Ask Paul podcast.
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Speaker 1: All right. Today, we're gonna be talking.
Speaker 2: About a question that was submitted to me in the
Let's Ask. Paul was asking about pullboxes and or a
metal wireway that is imposed on a raceway run and
whether or not you had to meet the pullbox requirements
even though it was technically not a pullbox. And I'm
you know, everybody likes the code to be pretty much
black and white, and you know, I tell you what
it's written a certain way. I wish that everybody would
enforce the code a certain way. But in reality, some
people look at something and they bring up questions and
they say, well, what if. So at the end of
the day, the AHJ some things are just black and white, right,
it's just point blank it has to be a certain way.
But there's some things that could be argued. And here
are some things that that that you could create an
argument for or a position for. And again, the AHJ
AUTH already having jurisdiction. The inspector who is working on
behalf of the actual AHJ, or maybe it's the building
official or the build UH, the UH administrator for the county,
whoever's done, you know, doing codes and and enforcement. At
the end of the day, they have the ultimate say.
That's their responsibility. A NEC is it's just a document.
If it's not adopted, it's not enforced, then it's really
what's the point in it?
Speaker 1: Right, So that's something we have to keep in mind.
Speaker 2: So in this case, the question, I'll read the question
and I'll tell you that and I've already emailed this
individual and I've gave them my position. There's two ways
to look at this, and I'm going to give you
the practical way that I would teach it. And I
remember for years I was the kind of Devil's advocate
kind of guy. And I used to remember or Phil
Simmons telling me one time, says, Paul'll tell people the
other way. Just tell them the way it's supposed to be,
and and you know, and that means that's the way
that I thought it would be.
Speaker 1: And he's like, that's enough, and whereat.
Speaker 2: I always would give you what it's supposed to be,
what I thought it was in the code, and then
I'll give you the devil's advocate response. And again you
can say, well shit, you just just tell me what
I'm supposed to do. And I don't like to do
that because I think all the people out there that
listen are free thinkers. Obviously, if you look at social media,
everybody's got an opinion, and I just have an opinion,
and I'll share my opinion and you can agree to disagree,
and that's fine. And you could say I'm full of crap.
That's fine too.
Speaker 1: I don't.
Speaker 2: I don't really care at this point in my life.
I really don't care what anybody thinks of me, really,
so it is what it is, right. I'm on the
downswing of life. If I could retire tomorrow and not
do anything, I just do it all right. Let me
read this out to you. So here's the question. It says,
I have a question about wire way. If I install
a twelve by twelve and I'm assuming he's me twelve
by twelve inch, I guess metal wireway above a four
hundred and anp panel board. It says a three point
five or three and a half trade size EMT is
passing straight down through the wireway on on the twelve
inch side to an eighteen inch nipple to the panel.
So basically, it's got a three and a half trade
size EMT coming into the top, coming into a wireway,
and then coming out of the bottom of the wireway
with a nipple that goes through the panel. We'll assume
the nipple is the same size three and a half,
which is still just a raceway. It's no definition of
a nipple. In the NEC we make references to length,
but the end of the day, a nipple, an EMT
nipple is still just EMT. It's still a raceway, just
happens to be a shorter one. Now it says I
only have two nineties in the run, so I don't
need to use the three sixty degree Okay, it's what
he says. It's a little grammar issue here, so I'm
just gonna paraphrase it, so y'all understand it.
Speaker 1: Okay.
Speaker 2: Now it says, does the wire have to be eight times?
The raceway size? Has stayed in three seventy six dot
twenty three b has me concerned?
Speaker 1: Why?
Speaker 2: Way, Phil, is not the concern. I appreciate all you
do for us little guys out in the field. Hey, y'all,
is what make the world go around. Okay, it's just
little you know, people like me that opine on this
and that. But at the end of the day, y'all,
y'all are what get it done. So again, don't ever
feel a little guy, y'all, all of the ones that
get it done, we're just here to support you.
Speaker 1: That's important. So let me answer this question.
Speaker 2: And the only way to answer this question is how
we logically would look at the installation if if somebody
and I've had this happen before, if somebody's pulling conductors
in a raceway and they are going to be exceeding
three hundred and sixty degrees worth of bens whether it's
offsets so, whether it's nineties, whatever it may be, then
they will install a box in there in order to
meet the pullbox to meet the three sixty rules, right,
no more than three sixty degrees between bins between points
right pull points. Okay, So the logic always was wash,
we'll put the box in there, then we comply with
the code.
Speaker 1: Okay.
Speaker 2: So let's say they were three hundred and eighty degrees
worth of bins. Okay, So somewhere in there before those
last couple binds, they'll put in a box. And their
argument is, and people's argument is is it a poolbox?
I mean, at the end of the day, am I
going to pull out of it? Well, obviously, as far
as the code's concerned, it's a poolbox, so that you
don't have more than three hundred and sixty degrees between
pool points.
Speaker 1: It does not dictate that you use it. That's a
code rule.
Speaker 2: So you put the pullbox in, you're probably still going
to pull straight through it, provided you've done a pull
calculation and you know what to do with the pull calculation.
And by the way, we do pull calculations for people. Okay,
So at the end of the day, when an inspector
looks at that, it's whether you use it or not.
Speaker 1: It's still a pullbox.
Speaker 2: You're literally are pulling conductors through it, and whether you
you use it or not is irrelevant. So with that said,
under those rules, you would have to put a pullbox
in there or a box in there that meets all
the rules that be required as if it was a
pullbox a pullbox.
Speaker 1: Right, you'd still have to meet those rules. Right.
Speaker 2: So you have these rules in three fourteen dot twenty eight,
and they talk about uh straight pulls straight as eight
or angles or splices. It's six times the largest raceway.
Now with the angles, it's plus the sum of the
other raceways in the same row on the same side.
So all these rules would still be in play regardless
of whether or not you use the pullbox or you
don't even want to call it a pullbox. The reality
is if conductors are passing through it, it could conceivably
be used as a pullbox. So you have to meet
the requirements of three fourteen dot twenty eight. Okay, it
just is what it is. Now the question comes up
and it's like this one where the gentleman says, you know,
we put a wireway up there that's interposed into the
raceway run. We're not doing it to meet the three
because we have an issue with three hundred and sixty
degrees of binds between poll points. We don't have an
issue that we just wanted to put a wireway up
there for whatever reason.
Speaker 1: Okay.
Speaker 2: And so you call it not a pullbox. You just
say I just put a wireway up there. I mean,
that's that's what you're saying.
Speaker 1: Okay.
Speaker 2: So if you're going with me down this chain of thought,
we're gonna look at that now. In doing so, we're
gonna have to go look at article three seventy six.
Speaker 1: Now, three seventy six is dealing.
Speaker 2: With wireways, okay, and so because he said this was
a metal wireway, So that's what we're dealing with.
Speaker 1: Now.
Speaker 2: If you go look at three seventy six dot twenty three,
which is titled insulated conductors, okay, so we're talking about
insulated conductors th HHN thw N DASH to x HHW whatever,
insulated conductors. It says that in slated conductors installed in
metal wireways shall comply with three seventy six dot twenty
three A and B.
Speaker 1: Okay.
Speaker 2: So it tells us right off the bat, if you're
installing insulating conductors inside of a wireway, you're going to
have to meet the rules of three seventy six do
twenty three A and B. Now A is dealing with
deflexion of those insulated conductors, okay. So that is where
the conductors come into the box or come into the
wireway right either into the wireway or whatever, and how
it moves through the actual wireway, and the deflection of
those conductors. Okay, So as they come in, enter and leave,
or the direction of the metal wireway itself is deflected
greater than thirty degrees demension and dimensions, then you have
to follow the requirements of the one wire perternal in
table three twelve dot six A shall apply. So you
have deflection rules, and we have a table that deals
with deflection rules, okay, and you use the spacing.
Speaker 1: It's one wire per terminal.
Speaker 2: And we've actually, I think I've done some videos or
training on that deflection not.
Speaker 1: The topic of this question though.
Speaker 2: It's not about deflection because in this case, the raceway
came into the top of the twelve inch twelve x
twelve wireway and came straight out.
Speaker 1: Of the bottom of the wireway.
Speaker 2: So the question is is that a pullbox is just
a junction box. What is the purpose of the box?
And then we're also going to think from an inspector's perspective.
If I'm looking at it, I'm wondering why they hell
did you put this box in there? So you have
to ask yourself some important questions about this. Now here's
what it says in B three seventy six, at twenty
three B. It says metal wireways used as a pullbox. Now,
a lot of people will look at that charging statement
and immediately we'll say, and here's the devil's advocates.
Speaker 1: You're ready.
Speaker 2: They'll say, well, this gentleman put this box in here,
but he's not using it as a pullbox. Therefore this
rule doesn't apply because it's not being used as a poolbox. Well,
the question about that really comes into the fact that
even when you're looking at three fourteen twenty eight A
one and A two, and you're looking at eight times
and okay, that's the requirements for the mentions of the
box that's used as a pullbox.
Speaker 1: Okay, but it.
Speaker 2: Doesn't go short in defining in the NEEC what the hell,
a poolbox is by nature, so any box that I
pull conductors through it can be argued is it's.
Speaker 1: A pullbox, right.
Speaker 2: I mean, that's what we're talking about, not just for
you to pull in and conductors in and out during
a raceway pull application. I mean, that's the most practical reason.
But at the end of the day, what did I say.
I said, if you had a raceway and you were
going to exceed three sixty, the way you do it
is you drop a pullbox in there. Whether you use
it or not, it goes in there to meet the
code requirements so that you don't have more than three
hundred sixty degrees between pull points. So you're just putting
the box in there as an exercise, You're probably going
to pull it straight through that box, okay, you know,
unless there is some type of deflection you gotta worry about,
But normally you're gonna pull it straight through the box.
Speaker 1: Okay.
Speaker 2: So, by by pure nature it's a pullbox. So when
you read this, there us be the devil's advocates. Again,
this may be your argument if you run into this
in your jurisdiction and you have an HJ that will
listen to you then you can argue this says this
rule only applies when metal wireway is used as a pullbox.
But the sheer fact that you're pulling conductors through it,
whether you use it or not for a pull itself,
it's still a pullbox, Okay, as far as those those
are concerned. So here's what it says. It says, we're
in insulated conductors of four awg or larger are pulled.
Listen to how it says pulled through a wire way, right,
it says, And remember, the title is one thing, it's charge.
It kind of sets the tone. But the code language
is the code language. And I'm reading you the code language. Okay,
not just the header, but the language. It says again,
where insulated conductors of four and larger are pulled through
a wireway, Comma, the distance between raceway and cable entry
enclosing the same conductors shall not be less than that
means they're coming in and passing straight through into another
wiring method okay, another raceway whatnot or cable assembly. It
says shall not be less than that required by three
fourteen dot twenty eight A one for straight pulls, which
is eight times and three fourteen dot twenty eight A two.
Speaker 1: Which is six times for ingle polls.
Speaker 2: Okay, where transposing cable sizes into a raceway size the
minimum metric designator or trade size raceway required for the
number and size conductors in the cable shall be used.
So that basically means that if you're using an MC cable,
look at the number of conductors, look at what insulated conductor,
look what's in there, and then do a calculation as
if it was a raceway. You can choose whichever one
you want, okay, but you find a raceway and to
make sure that that's what's going to basically give you
the size trade size, like if it was a raceway,
even though it's an MC and that doesn't come in
trade sizes like that, you don't do it the same way.
But if all the conductors in an MC cable, let's
say we're being used in this box going through this
wireway and it was MC, and you're trying to do
the numbers in order to meet the eight times or
six times depending in this case would just be eight
times because it's a straight through pool, then you would
determine what would be the size raceway and usually we
would use the same size of the raceway I it's
coming in. Like, for example, if it was EMT coming in,
but it was MC going out, then we're going to
basically calculate it out on what would be the minimum
size raceway if it was EMT, because that's what's feeding it. Now,
if it's all EMC coming in and MC going out,
then you just have to pick and say, Okay, I'm
going to use EMT and I want to find out
what would be the minimum size I would need to
be able to hold all these conductors and not exceed
the forty percent fill, and then that's the size raceway
I go with.
Speaker 1: And I would do that.
Speaker 2: Times eight, and that's my dimension, okay, Or in this case,
since it would be MC, then it wouldn't be a
straight through, it would be splices, so it'd be six
times obviously in that example.
Speaker 1: But you get the point.
Speaker 2: So it's my opinion that regardless if you if you
transpose and you put a wireway in between a run
and your only effort is to pull straight through that
wire way, then I believe that it is being used
as a pullbox. You do have the ability to pull
it from there. Okay, that's what I believe, all right.
So as a result, I think you have to meet
the requirements of three fourteen twenty eight a one or
eight two, the eight times or the six times, whether
your angle or splices or you're.
Speaker 1: Straight as eight.
Speaker 2: And so adding the pullbox and saying or adding the
box or in this case the wireway and saying, well,
I'm not using it, then what did you put it
there for?
Speaker 1: I mean, what's the purpose.
Speaker 2: If the conductors are passing through it, then they're being
pulled through the box. So your only argument to an
HJ is obviously if you put this this wireway in there,
and in this case it was a twelve x twelve,
which I don't believe is going to be adequate because
if you follow the rules again he said it was
a three point five or three and a half, So
three point five times eight, it needed to be at
least twenty eight inches in straight from top to bottom.
Not the width okay, because there was no pulls mentioned
anything like that. So in this case, it's just the
width of it is to accommodate the raceways, and the
depth of it was to a commodate the raceways.
Speaker 1: And the locknuts or whatnot.
Speaker 2: Right, So this case, it was a straight pull through.
So I think that your your box, your your wireway,
whether you intend to use it as a pullbox or not.
It is my belief that that still has to meet
the requirements. And that's why it makes references back to
three fourteen twenty eight, whereas you get the A one
and A two.
Speaker 1: I think that's the intent personally.
Speaker 2: And in researching it and looking at a little bit
from other people that I know and looking at that,
they kind of gel with the same kind of interpretation.
And I'm giving for that. You can agree to disagree.
You know, again, it falls back to me. It falls
back on the question what did you put the what
did you put the wireway in? Therefore, if you're coming
in with the three and a half or yea three
point five or trade size three and a half coming
into the top and coming straight out the bottom, even
if it's a nipple eighteen inches, the question is what.
Speaker 1: Did you put that box in? Four?
Speaker 2: So if they're insulated for gauging larger, then to me,
you're putting it in as a perceived pullbox.
Speaker 1: Whether you use it or not, it's going to have
to be perceived that way.
Speaker 2: And I don't know any other way that the electrical
inspector can't look at it. I mean, especially if it's
not put in there. For example, like I said earlier,
people put boxes in when they know that they're going
to have more than three hundred and sixty degrees worth
of bins between pull points. So what do they do
They put in a pull point. They'll put it in
now whether they use it or not or pass right
through it, pull it. They probably aren't going to use it,
but it still would need to be the proper size
regardless because it could be used as a pull point.
Speaker 1: Right.
Speaker 2: So at the end of the day, I think the
you know, AHJ inspector's going to have to make the
call and say, you know what, it is plausible to
be considered a pullbox.
Speaker 1: You are definitely pulling conductors through it.
Speaker 2: I don't control what you do after I'm not here,
so it looks to me and so it doesn't meet
the dimensions that are required for a pullbox in this situation.
So again that's where I think that most of the
age j's are going to lean in the box is
too small or the wire way is too small. Okay,
all right, hopefully, I answered that question. That's my opinion.
You can agree to disagree, but that's my position on it.
I believe that you are going to have to follow
the requirements as if it was indeed being used as
a pullbox that type of thing. Okay, all right, that's
my opinion. You can agree to disagree. What's next. Okay,
So the next one we've got here is one that's
actually asking for my opinion, So I will give an opinion.
I will say up front on this one, just so
you know, I am not an expert in HVAC equipment.
I am not an expert in the HVAC standards like yeah,
UL nineteen ninety five. I don't have anything to do
with that industry, Okay, So this is just asking me
a question, and so I can only answer it based
on what I know from the NEC. And there seems
like there's a mechanical industry, the HVA industry, that has
a disconnect pun intended with what we do. So let's
talk about it real quick. So here's the question that
says Ee from New Jersey here. I love the podcast,
but I am a new listener, so I may so
my question may have been answered on a previous podcast
please point me to that release date and I will listen.
Speaker 1: Okay, Well, I can.
Speaker 2: Tell you, based on your question, it has not been
discussed at a previous date, so I can only talk
to you about what I know as of today. And again,
I am not up on other industry standards as well
as you may be as an engineer who may design
systems then you're looking at these things. I just follow
the NEC. I'm just an NEC guy. Okay, So that's.
Speaker 1: All I can follow in this scenario, So let me
go and read it to you. It says.
Speaker 2: Says I would love to hear your take on the
sec R And for those that aren't familiar, that's the
short circuit current rating that we typically see on electrical equipment.
You have a panel board inside of a cabinet typically
that you would have an SECR rating on the cabinet
and in the in the panel board, and all of
that together is going to give you an SECR rating.
And then of course you have like overcurrent protective devices
that give you the AIC rating. All of this is
covered in one ten dot nine and one ten ten
of the National Electrical Code. Okay, that's to the extent
that I involve myself when it comes to this type
of thing. Okay, I assume when I purchase a piece
of equipment that I know what the available fault current
is at the location where I'm putting the equipment, and
I get my equipment accordingly, I might have to specify
certain sec DR rating on a piece of equipment as
well as a C rating if there's overcurrent protected devices involved.
I have to make that selection because I have to
be fully aware of what my available fault current is
at any point in the system, especially now more in
the NEC as it expands out for us to require
labeling and all this type of stuff in order to
be able to tell somebody what the SECR rating is,
what the AIC ratings is, which available fault current rating is.
All this kind of good stuff seems to be expanding
throughout the n NEEC. So manufacturers need to be more
diligent obviously on giving information on equipment, whether it's on
their nameplate, data sheetor whatever, because we're getting more and
more intricate and how we design systems, and the electrical
engineers that are having to design these systems are having
to look at all these things, and sometimes certain things
doesn't jail very well with other industries. Okay, so he
wants my take on this, and it's about the SECR
rating for HVAC equipment. Now, he says, HVAC equipment usually
has an SCCR rating of five thousand amps, and the
available fault can pretty commonly be higher than this for
larger equipment. It says, I always called for fuse disconnect
switches to limit the let through, but what I am
learning is that there could still be a fraction of
a second where the unit sees the higher current while
the fusee clears the fault. And the right and the
right way to do this is actually requests the HVAC
unit to be listed with a higher sec already. That
is absolutely correct and in many cases, you know, we
talk circuit breakers all the time and their minimum ratings
and in series ratings and and and all this type
of thing. And we've also talked about that where the
available fault current as it gets further in to a
structure will start to diminish, right because of impedance and
the other things that it has to go through, So
it starts to go down, so it doesn't.
Speaker 1: Typically get higher.
Speaker 2: But depending on where this equipment's located close to the source. Again,
can plan have an effect on the equipment. So the
right thing to do would be is to review all this,
look at the available fault current and it's just more
that the engineer is going to have to be aware of.
And I would kind of tell the electrical engineers and
you need to push back a lot against the mechanical
engineers and the manufacturers HVAC equipment if they're going to
be installed at a point in the system where the
available fault current can affect what might be a posted
SECR rating on a piece of equipment, or if it
has an overcurrent device in there, an AIC rating on
a piece of equipment, we have to push back. You
have to push back now when we think about it,
it's a real world problem, right is that most of
the HVAC equipment that I'm aware of, and what research,
little research I've done, you have the commercial package unit,
it's the rooftop units, the VRFs and the VRV outdoor units.
All of these are a factory and from what I'm seeing,
and again I'm not an expert, but what I'm seeing
is a lot of those do.
Speaker 1: Come with an SECR rating on the equipment. At five.
Speaker 2: At the five k va oka or five K five thousand.
Speaker 1: Amps, sorry five thousand, gonna say VA.
Speaker 2: Five thousand amps, right, And so I'm seeing that's pretty
common unless they're marked otherwise or less it's a specific
piece of equipment that's being made and have it evaluated
at a higher volt amp rating. Okay, higher amp rating
getting a tongue tie today. So now the lower SECR
rating is often a problem because it's typical for an
available fall current on commercial buildings, depending on where this
HVAC equipment is located, to be as high as eighteen
thousand up to sixty five thousand amps for a specific
period of time of this available fault current and assuming
that the equipment can handle this. Now, it's typically what
we look at is if we have and what they'll
argue is that what we have is the main equipment
that's coming in is typically going to have a higher
AMP rating, right, So you're going to have the SECR
rating on the equipment where the service comes in, and
the overcurrent protected devices an AIC rating are going to
be more than adequate to handle the available fault current
from the utility that's supplied at that point and as
it goes downstream into the building, this number is going
to decline, right. So this is kind of one of
those things where if your equipment upstream is series rated
and so we have all this series rating on the
overcurrent and all that type of stuff, then it typically
typically will trickle downstream. And it may be, and I
don't know the answer to this, it may be the
question needs to be asked to the manufacturer if this
scc R rating that they're putting on their equipment has
factored in the fact that you have a SECR rating
on equipment that's at the service in the AIC ratings
on various overcurrent devices will dissipate further as it comes
into the building, And the question is if they taken
that into consideration when they did their five thousand app
SECR rating on the equipment.
Speaker 1: They may or may not know that.
Speaker 2: Answer, and it also does not mandate the fact that
that equipment is probably not having.
Speaker 1: Anything to do with anything remotely near series ratings.
Speaker 2: So again it's just me speculating because that's how it
typically works with the overcurrent protected devices and all that
kind of stuff when you did a series rating in
a panel board, for example.
Speaker 1: So I'm just.
Speaker 2: Purely speculating on that aspect. But that's a good conversation
that needs to be had with the manufacturers of this
HVAC equipment. Again, the commercial package units, the CPUs, the
rooftop units, the VRFs and the vrvs that are outdoor units,
all those types of things. These are conversations that really
do need to be had with the manufacturers of those equipment. Now,
the one question I will tell you that why fuses
don't actually solve this They may help the issue, right,
but they don't necessarily solve this issue because if you
select the properly selected current limiting FUSEE for example, now
it may mitigate the energy that let through, right, but
it does not, for any reason increase the SECR rating
on the equipment to which it's installed or installed in
conjunction with.
Speaker 1: So while you may be doing this to solve.
Speaker 2: A problem, this does not change the SECR rating or
that's on the label of the equipment in any way.
So this is just being a proactive step that is
being done by the design professional.
Speaker 1: And they have every right to do that.
Speaker 2: And again they this is what this gentleman has done
in order to mitigate some of the risk here that's involved.
But I will tell you that that does not just
because you install fuses in line, that does not increase
the SECR rating of any equipment. In fact, most of
the HVAC equipments and nameplates don't even recognize any fusing
in the field as a valid solution to increase any
SCCR ratings on the equipment. It's not something they're going
to take into consideration, right And if you go look
at the various standards UL nineteen ninety five for example,
for HVAC standards, unless they mandate something or stipulate that
a fuse in line or something like that will raise
the SECR rating, unless they give you some scheme that
you have to do to do that, then the fact
of the matter is that you're stuck at five thousand
amps and that's it.
Speaker 1: Now.
Speaker 2: Again, it may be a diminishing factor where you put
it on the system. And maybe while we're not seeing
a lot of issues with this, I mean, I'm not
assuming this engineer has seen a lot of these issues.
Sounds like he's mitigating it out by putting fuses in there,
but it doesn't necessarily mean the fuse is going to
cause the problem. Because you before the fuse clears, you
have a high level of this fault current that could
still cause a problem on the HVAC equipment. So again
figuring out how the fusing works, but again that's not
going to change the manufacturer's SEDR. So what you're doing
is you're doing something that you hope will mitigate the
risk to the best you can. That's about it. But
the manufacturers seem pretty silent when it comes to that. Now,
why it matters as far as the NEC is concerned, Well,
the NEC one ten dot ten requires that equipment interruptive
capacity be suitable for the available fault current. Okay, so
that requires it equipment and so at this point it's
in conflict with the manufacturers statement of five thousand amps.
Speaker 1: Okay.
Speaker 2: So again, next is the one ten dot nine that
applies to the overcurrent protecting device.
Speaker 1: But again HVAC units have built in.
Speaker 2: Controllers, contactors, control transformers, all that kind of stuff that
must be protected, not just a disconnect or a circuit breaker.
So the one ten dot nine is more specific to
overcurrent protected device. But there are obviously other things within
the componentry of these units, these HVAC units that need
to be protected. So a one, ten, dot nine does
not specifically address the internal or any other type of
component that's built into the actual HVAC unit. Right now,
one of the things that we have to worry about
is if you fail to coordinate any SECR rating, then
what happens.
Speaker 1: It could lead to bigger.
Speaker 2: Issues, right and it could lead to where the available
fault current at this piece of HVAC equipment was far
exceeding the five thousand. Now, like I said, I am
I'm going to be totally honest here, I have not
heard of any major issues here. I really haven't. Now
what could that be for? Well, it could be that
we just have solid systems that are not seeing the faults.
We're not seeing an available fault condition, We're not seeing
you know, these things that would bring question to the installation.
And that's not the resiliency of the of the of
the of the products. That's probably the testament to the engineer,
you know, the design and the people that are installing it.
Maybe that type of thing. They're just doing a better
job now. But I imagine if you had a lot
more of events that took place, Uh, then you got
to question who's liable is it if the available fault
current was higher at the HVC equipment and it was
only five thousand amps and somebody got hurt.
Speaker 1: Is it the engineer's problem?
Speaker 2: And this is why this engineer is installing these fuses
to try to mitigate as much liability probably as possible.
Speaker 1: Is it the manufacturers of the HVAC.
Speaker 2: Equipment that's liable? It's certainly you got a question is
it the installer? Because the installer needs to know what
the available fault current and if he's installing something on
a system and it's far less than the available fault
current at that point, it can he actually install it?
But it gets done all the time, right. So the
one thing about the designers here is they rarely ask
for any SECR documentation from an HVAC rep.
Speaker 1: I'm probably never do that.
Speaker 2: They probably never ask the people that are going to
supply the equipment and say, hey, what is your documentation?
What is the SECR rating? If I need a higher rating?
What can I do?
Speaker 1: What can do?
Speaker 2: Is it special equipment? It's you know, it's kind of
a kin do I tell people all the time? You
know with mc cable, you know mc cable people want
to run it in parallel, and they want to know
why the equipment ground's not large enough. And I'm like,
because we don't make MC cable for it to be
run in parallel. You're choosing to run MC cable in parallel.
We manufacture MC cable to be protected at its opacity
for the conductors that are in it as a single
cable assembly, not to be installed in parallel. That doesn't
mean you can't do it, but this is where you
run into the problems with an undersized equipment ground. Now, yes,
we have some allowances in two fifty one twenty two
f that can help us do that by running a
single one and connecting all ends together and YadA, YadA, YadA.
We have some provisions that over the years we said,
you know, we got to do something because you know what,
we can't make a special limsey for everybody or a
special trade cable for everybody, so we have to come
up with some allowances. Okay, same kind of scenario here.
Where this is a situation is the SECR rating has
to be what it is based on where this equipment
is going to be located. That type of scenario, so
probably should be designers should be asking the SECR value
or trying to get that from the HVAC people right
up front, especially if they know that this is going
to be an issue, and obviously this is an issue.
Next inspectors, now, the electrical inspector, you know, the task
they have in itself is evaluating a building and looking
at everything right, But they don't typically stop and check
the fusing and circuit breaker sizing and specifically look to
verify SECR ratings and the available fault currents at this location.
They assume that that's been done. They're looking to see
whether the fuses a circuit breaker are protecting the conductor
because that's what it's there to do to protect the
conductor and probably by vicariously through that protection, it may
also protect the equipment. But the real focus is to
protect the wire and the conductors right, So that's the overcroptet.
So that's what they're looking for, making sure that everything
sized properly, that that conductor is still going to be protected.
Speaker 1: So that's their daily job.
Speaker 2: They don't go around thinking about hmm, this HVAC equipment
has an SECR rating less than what could be required.
And also it's an industry thing because we require certain
types of evaluations for certain equipment. But I'm not aware
unless I'm wrong here and somebody will tell me in
a follow up post, is that I don't believe we
have an SECR mandates specificquickly driven in four forty two
HVAC equipment. I think it just follows the normal electrical
equipment and normal stuff that would be SECR. But we
would argue that an HVAC unit is not electrical equipment.
It connects to electrical system, but it's not the same.
So we cover the fuses, we cover the disconnects, we
cover the breakers, We cover all of those type of
things which are electrical with an SECR rating and and
have to worry about in many cases available for all current,
but we don't think that much about the actual HVAC unit. Now, contractors,
you know, they may assume that the fuses fixes everything, right,
but the fact of the matter is that the let
through still happens before the fuse opens, and so the
factory listed SECR is the controlling factor in again, that
is to allow a certain amount of current to be
presented and not blow up the equipment. Well, if that
thing is only ready for five thousand amps and eighteen
thousands getting through. Then that's going to get through before
the fuse blows. Then you still pose a risk due
to the components and everything is an the SECR rating
only being five thousand. Again, I'm not seeing a lot
of this in the industry. I'm not seeing a lot
of failures that people are complaining and arguing.
Speaker 1: But there is a possibility for this issue, right.
Speaker 2: So one of the ways that we can fix this
is that we need to specify an SECR rating on
any submittal. So any of that, ee, any of the
submittals you submit in and you know what the available
fault kurt, then you need to submit for a certain
value and then let the manufacturers of the equipment say, oh,
we don't do that, or you got to pay extra
for this, or it's another evaluation for this because you're
asking them to give me the rationale. And maybe they've
done some testing. We're in series ten and all this
kind of stuff, like with the regular circuit breaker behind
a main breaker. Maybe they've done some testing. I'm just
not aware of it. Okay, I'm not smart enough for that.
I don't I'm not that intelligent to be able to
give you an answer on that. But when it comes
to the HVAC equipments, if it's posted at five thousand
amps and it's being put at a location that could
present to it the available fault current much higher than that,
then that seems a problem to me. So if I
know this is an issue, then I'm going to specify
an SECR rating on a submittle, just like we would
do for panels, just like we would do for control panels.
We're going to force the HVAC manufacturers to list the
equipment accordingly, right, And this might spawn change into the
industry where the manufacturers say, Okay, we need to kind
of create these SECR ratings that are more in line
with panel boards, control panels and all this type of stuff, unless, again,
they've done some testing where it's downstream and it supposedly
dissipates out enough that it's not an issue by the
time it gets to the equipment. Again, I'm not smart
enough to know if they do that. I don't research that.
That's not my thing, right, I don't daily think about
that kind of stuff, and I'm not the smartest one
out there. There's other educators that may have a better
answer for that, but I don't have a better answer
for that, and also at the end of the day
document the available fault current. And again, one of the
things that you're going to do if you're a plan reviewer,
ee are designing something is just asked for the information
from the HVAC manufacturer to make sure that they have
accommodated the available fault current and what the rating and
SECR is at the location where this equipment is being stalled.
If you're concerned about it, because I'm telling you the
industry itself obviously have been doing this for years and
not concerning themselves with it. Makes me believe there's got
to be something behind it that that the manufacturers say, look,
we're series rated or something, uh on, whatever it may be.
I don't know the answer, so I cannot be that
much of a help to you. I just kind of
gave you some thoughts on that, right it says, let's
see here, uh he says, I think this is a
massive whiff in the whole industry that is hardly picked
up by designers and inspectors.
Speaker 1: What are my thoughts, Well, those were my thoughts. You
asked for it.
Speaker 2: If if if the available fault current at this equipment
exceeds five thousand and the and the standard is five thousand,
then that's a problem. Does the NEC mandate fusing. Again,
depending on what the available fault current is and the fuse,
it may or may not provide that level of protection
it's necessary. So the end, you know, is there something
that needs to be done in the industry.
Speaker 1: I don't know.
Speaker 2: Again, I'm not smart enough in that field to be
able to know that. All I know that people are
installing HVAC rooftop units CPUs all the time, all the time,
and I'm not seeing a big issue.
Speaker 1: I'm not seeing people.
Speaker 2: I mean, look, somebody got electrocuted for caring in a
cross space on one hundred and twenty volt lighting outlet
and that got into code. Somebody got hurt leaning over
an outdoor HVAC unit and that's what spawned two ten
dot eight f to we have GFCI protections, you know
what I'm saying.
Speaker 1: People got shocked by.
Speaker 2: Dispposably ranges and ovens or whatnot, and that spawned the
change for GFCI expansion.
Speaker 1: I don't know. I don't know.
Speaker 2: I don't know enough about this topic to say that
this is a big issue.
Speaker 1: But I can tell you just on the surface.
Speaker 2: If the available fault current at an HVAC unit is
eighteen thousand amps and your SCCR rating for the equipment
is only five thousand amps, that's a problem. And if
putting a fuse on it can help mitigate it to extent. Okay,
maybe that'll work. But because of how those fuses are
rated that type of thing, there's still gonna be a
certain amount of let through that gets through that could
cause a problem. Hey, it may not cause the equipment
to blow up, and maybe that's the effort, maybe that's
the goal. But again, this engineer puts disconnects, which is
probably you know, an extra element that that that you know,
helps them sleep at night.
Speaker 1: I don't Hey, I'm all for it.
Speaker 2: Maybe something should be submitted, but it is a it
is a fact that that amount of let current let
through current instantly before the fuse blows could be exceedingly
higher than the rating of the equipment and then calls
the equipment to to have a problem burn or burn up.
Speaker 1: Again, I don't know enough on it.
Speaker 2: How quickly what the let through The reaction time is
very quick with an overcurrent protective device, so it may
be that that mitigates it down. If anybody out there
knows deeper than that, please let me know. And I
think one of the biggest I guess one of the
biggest things that we have to understand is we're still
sitting on a violation. We're still violating one ten dot ten.
So even though you're adding current limited fuses or circuit breakers,
and it can limit the energy the let through energy,
but the key crux here is that doing so is
something that you're doing as an engineer and it does
not legally raise any SECR rating of the equipment itself
unless the equipment manufacturer tested and listed it with that
specific fusor circuit breaker and marked it accordingly to be
something that does raise the SECR rating. Otherwise you're still
having a violation of NEC one ten dot ten because
the equipment is exposed to available fault current above its
SECR rating. Regardless of that let through energy, it's still
gonna be a violation of one ten dot ten. So
adding to fuses because there's a lack in the industry,
maybe maybe a solution, a temporary solution to a bigger problem.
Now SCCR for those that aren't familiar with that that
is based on a maximum fault current the equipment can
withstand okay, without any catastrophic failure during the clearing time
process of an overcurrent protected device. Okay, because you have
this various clearing times. Now current limiting devices we can
talk about, for example, like a class J fuses, RK
one lt fuses, and certain mccbs, various types.
Speaker 1: Again, in some of those with adjustable trip curves.
Speaker 2: Okay, they can reduce the is square t Okay, that's
the current square time's time that peak let through current
gets through.
Speaker 1: Okay, that they can indeed limit that.
Speaker 2: But the first cycle of a fault, which we call
the half cycle, okay, can be tens and thousands of
amps before the fuse even opens. So many HVAC components,
especially the contactors, the control boards that may be mounted
on it, the transformers that may be integraled into the system,
they can fail in that first cycle when exposed to
currents beyond their design limits. Again, if they were limited
to SECR five thousand, Okay, even if the total energy
let through happens to be reduced, it still can cause
an issue and still can cause things to blow up
and cause a hazard.
Speaker 1: Right, So, as far as the NEC is concerned.
Speaker 2: In the UL perspective, ANYC one carries cares only about
the to total thought of total fault current available okay,
not about energy mitigation, okay, it only cares about the
total fault current available UL nineteen ninety five and UIL
six sixty three three five DASH two DASH forty, which
again I am not familiar with. I pull that up
and doing some research that requires HVAC assemblies to be
tested and marked with an sec ARE based on what
they can survive with listed overcurrent protected devices. And obviously
the standard we've learned as the industry is five thousand amps.
Speaker 1: Right now, you can't just say I installed a fuse.
Speaker 2: This engineer is doing this for his own you know, comfort,
and I don't think he's doing this. But he's not
saying I installed a fuse or I mandated you install
a fuse. But you just ignore the SECR nameplate, okay,
because the markings is governed by industry compliance.
Speaker 1: Right.
Speaker 2: So again, the rating of the nameplate is what it is,
it's what it was evaluated to, Okay. So the bottom
line takeaways that I want to think about is an
HVAC unit marked five KA SECR and has a thirty
thousand amp available fault current that is fused with Class J.
That is not compliant. It's not going to meet. Anything
to do with the secrate is gonna be a violation
of one ten dot T Why because the SECR is
too low.
Speaker 1: Regardless of the fuse.
Speaker 2: It needs a factory listing in order to raise the
SECR value. Now, if you have an HVAC unit marked
with thirty thousand amps SECR with a Class jfuse, guess
what that's compliant. Why because the manufacturer has tested with
a Class J okay, and the proper SECR markings are
on the enclosure.
Speaker 1: That would be compliant.
Speaker 2: Now if I have an HVAC unit marked for five
k or five thousand amps SECR and it has a
low available fault current at four thousand amps based on
you know, how far it progresses into the building or
into the structure where the available fault current drops, well,
then that's okay. Because that fault current is within the SECR.
Speaker 1: That's not an issue.
Speaker 2: So I think a lot of this and you say
five thousand is too low. It's really going to be
dependent on where it's installed into the system and I
think a lot of this HVAC industry thinks, well, look,
it's coming in through the service, it's going into the
main panel, it's probably hitting a feeder, it's coming out,
then it's going to it's.
Speaker 1: Traveling further into the building.
Speaker 2: And that's probably why the five thousand amps has always
been adequate.
Speaker 1: I don't know. I don't do these testing, so I
don't I can't say that.
Speaker 2: Now field fusing without the SECR markings increase means you
just putting a fuse in it. It still doesn't make
it compliant, right because the SECR is still limited by
the name plate rating. That that's that's the deal. Okay, Now, practicalness,
you can mitigate energy with current limiting fuses to reduce
the damage overall damage to people prop you know, people
involved in it, right, but you cannot claim that it's
code compliant on SECR unless the name plate actually says
it is so.
Speaker 1: So no adding of the fuses is going to change
any of that in the equation. Right.
Speaker 2: So the big question that people ask me, or will
ask me this gentleman may ask me.
Speaker 1: Is well, do fuses of circubrators hurt anything?
Speaker 2: Yeah, as long as you're not claiming to change the
SECR rating, and you've done an evaluation in the available
fault current at that HVAC equipment is higher than the
five thousand, then putting the fuses in there are not
going to do anything but probably save a massive issue.
But it's certainly not gonna save equipment. And there's still
gonna be issues because of that five thousand SECR rating.
I can't tell you what the effects will be. I'm
not sure like what will blow up and what won't.
But what I can tell you is that even if
it's not going to change the SECR rating, and you
know there's an industry issue, I encourage you to still
recommend the fuses and circuit breakers as well because they
will help because they're going to reduce the damaged potential.
Even if they don't fix the SECR compliance issue, they
will help address it.
Speaker 1: Why well, because.
Speaker 2: Current limiting fuses and breakers reduce the peak current that
let through current during the short circuit event. Again, may
not save the equipment, may not save the contactors, the relays,
the transformer, may not save that, okay, And what that
means is that the severity of the fault on the
equipment is going to be lessened, and it may be
a replaceable thing. You may be able to you can
place a transform you whatever that think. Okay, you may
prevent the explosion, the fire, or catastrophe or catastrophic failure.
Even when the SECR is technically too low, it may
help in the condition. It's certainly not going to hurt it. Okay,
So kind of And I don't know an example. If
I think of a mental picture example, I think of
it like wearing a seat belt in a crash. Right,
it doesn't change the fact that you hit a wall
at sixty miles per hour, but it reduces the chance
of a fatality. So it doesn't solve the SECR rating.
It's better than nothing. If there's a issue in the
industry and your available fault current at the point we
are can exceed the rating of the HVC equipment, then
it would probably be prudent to add some currenting limiting device,
circuit breaker refuse in the system in order to limit
the damage, not totally remove it. Limit the damage. Right,
But at the end of the day, we have to
think about code enforcement. You're still going to get issues
cause one doesn't care just about the reduced damage right.
It doesn't care about that. You're oh, it could be
less than it could be. It doesn't care about that.
It requires it equipment to be available to withstand the
available fault current without failing, which is why the SECR
nameplate governs this compliance. Okay, it's been evaluated for it.
Speaker 1: Okay.
Speaker 2: Now, in a lawsuit, okay, a post incident investigation we
call it, you can't defend it by saying I installed
current limiting fuses even if the available fault current exceeds
the SECR ratio of equipment. That's not a valid legal argument.
You're going to lose that argument. So the best thing
you can do is say, hey, if I've got eighteen
thousand amps here, this unit is ready for five thousand apps.
I know that it's eighteen thousand apps here. It's ex
seeding its SECR rating. Mister manufacturer, do you have anything
that will accommodate eighteen thousand amps? If their answer is no,
then all of you have to make the decision to
put in fuses to at least mitigate some of the damage,
not remove at all, but mitigate it. Okay, So I
kind of tell you have to think of this in layers.
You know, like a cake right, whereas fuses installed. When
you have an SECR that's too low, the outcome the
equipment may survive, but risks still remain. Is that compliant
with one no, So maybe that's the compromise. The next
thought is, okay, well, I'll put fuses are installed and
it is a.
Speaker 1: Proper sec are marked properly.
Speaker 2: Well, if that's the case, then the equipment will survive
and it complies with the code and it meets one
ten dot ten. And that means that you ask the
manufacture of the HVC equipment to increase the SECR rating
on that equipment or whatever they have to do accordingly, okay,
or tell you what you can do in order to
do that. Now, the worst case scenario is is you
have no fuses. So you, as an engineer, installing these fuses. Again,
I think that's the right thing to do. It's not
going to solve it all, but it may mitigate some
of the risks. Some of it still not compliant, but
mitigate some of the risks from an engineer's design standpoint.
Now you do no fuses and that sec R rating
is too low based on the available fall current, then
you have a high risk of catastrophic failure, certainly not compliant, right,
So bottom line, yes, fuses help reduce the real world risk,
doesn't eliminate it. But bear in mind that the National
Electrical Code is a minimum safety standard. It doesn't mitigate
all risks one hundred percent. It's a minimum safety standard.
So I definitely agree with the fuse in light of
this is the case. But bottom line, no, they don't
fix the compliance gap with the equipment. That's something that
needs to be a communication with the manufacturers of the
HVAC equipment.
Speaker 1: Right.
Speaker 2: So, practical reasons, fuses are better than nothing, okay, but
for pure compliance and liability issues, you need to make
the manufacturers come up to speed with this. SECR ratings
based on the location, unless they're saying that the five
thousand is based on how deep it is in the system,
where the available fault current drops rapidly as it moves
further into the system, that type of thing. Okay, all right,
that's a lot of information. Again, I'm going to argue
with everybody and say I am not the expert on
these things with HVAC equipments. I'm just assuming five thousand.
I'm sure they make a higher SECR rating. That's just
the industry standard, is what I'm reading and what I'm hearing,
and it correlates with what the engineer that sent the
question in. So my thoughts are recommendations. And again you
can say, I'm just saying, if there's nothing to be done,
it fuses or current limiting devices can help. It's not
going to mitigate at all, but it can help. And
we're just not seeing a big issue in the industry
of the faults blowing things up and this being the
result because of the SECR rating of the equipment. There's
usually bigger issues or bigger fish to fry. How do
you change this? Push back to the manufacturers if you're
worried about the available fault current at a piece of equipment,
even in areas where the NEC doesn't stipulate that you
have to be aware of available fault current. Okay, I'm
just saying, if you're concerned and your design is concerned
with the short circuit current rating of equipment and where
they're located on the system, then you have to push back.
You have to push back from the manufacturers, and also
if it's a known issue, you need to think about
presenting public inputs you know, to the code development process.
Speaker 1: I can't do that.
Speaker 2: I don't know that industry or it work closely with
those types of equipments and when it comes to that,
but if you are you are one of those, then
you need to deal more with it. You need to
get more involved. Otherwise we're not going to solve the problem.
If there's a problem there, you get me, okay. Anyway,
I don't know that I answered your question. I did
a lot of talking and I probably bored a lot
of people. And again, you don't need to get nasty
with me. I have told you over and over I
am not an expert when it comes to HVAC, how
they're constructed, what their short circuitcurrent rating is.
Speaker 1: I can only speak about what I know, and that's it.
Speaker 2: Until next time, folks, Stay safe, God bless and we'll
catch you on another episode of Let's Ask Paul Peace
p boo.
Speaker 1: Boo both no thing maskall, no thing boom