What's up, everybody? Welcome to another episode of Let's Ask Paul, the
podcast where I, Paul Abernathy, do my best to answer your electrical code
related questions submitted through our online portal at Paul Abernathy dot com. So before
we get into today's episode, I do have people that ask me, well,
Paul, what makes you qualified to answer people's code questions over people that
just posted on social media? What makes you so special? Well, first
of all, nothing makes me special. I feel happy, Oh so happy.
Oh maybe that's supposed to be I'm so special anyway, that isn't.
All I can tell you is that I have been doing this for thirty four
years. I am the founder and CEO of Electrical Code Academy. Also created
and trademarked the Certified Master Electrical Code Professional program that has certified professionals all over
the country. I've served for NIMA. I worked for National Electrical Manufacturers Association
as their NEC code expert in field rep for the southern sections about thirteen or
fourteen states. I've worked at as an engineer for the City of Richmond,
Virginia, overseeing inspections and plan review in the engineering department. I have worked
for City of Alexandria, Virginia. I was a head of the Code Inspectors
and the education on the NEC. I have was an electrical contractor for many,
many, many many years, twenty plus years. I tried to juggle
all that and tried to keep everything going for years and again. I am
director of technical services for a major manufacturer of wiring cable. So i've and
I've been. I've held all of my ICC inspection certifications from residential to commercial
to plan review. I'm a master electrician in multiple states. I could go
on and on and on. I've written books on the NEEC. I co
wrote books with Phil Simmons and for s Engage. Let's see what else.
My first book was written in two thousand and seven, which was purely for
electrical inspectors and home inspectors. Gosh, I don't know. I've over a
thousand episodes in podcasts. I'm all over social media, so my opinions are
out there, so I'm not this random guy that just puts them out there
on a message board doesn't do anything. Oh. I should also mention that
I serve on Code Making Panel five in Code Panel seventeen for the development of
the National Electrical Code, and I have for many cycles. So I'm just
not you know, I'm not special. Again, i am not, but
I have been around a little bit. And it's not to say that I
can't be wrong, but I am going to probably rely on my interpretation over
somebody that just randomly shows up on TikTok or Instagram or Facebook groups or whatever
and wants to beat their chest to seem intelligent. I don't need to get
into those arguments. You can look who I am. Just open your codebook
up. I'm in the front. It's not a big deal. Okay,
all right, Look why did I tell you all that. I told you
all that to be able to establish the fact that I'm just not your regular
Joe Schmoe that comes on here. I don't just write books and have never
served on a committee. I've served on UL committees, ASTM committees, NIMA
commit I have nine patents to my name in the wiring cable industry. I've
got tons of federal trademarks and service marks. So again, when I tell
you, somebody gives you questions and answers things for you. And this is
why it's so important to tell you about the free service at Paul Abernathy dot
com. I'm here for you. I'm here the answer questions for you.
Okay, the next generation of young folks is gonna have to pick up that
tab because a lot of us older folks are gonna be cashing in. Baby,
we're getting old. We ain't gonna be here long, Okay. The
Paul Abernathys, the Mike Holtz, the Ryan Jackson's of the world, they're
gonna go away. The Phil Simmons, the Charles Millers, We're all gonna
we're getting old. Okay. And I know, you know, people don't
want to hear that, but it is what it is. And so eventually
we're we're gonna check out to the big uh whatever, the the elect Trician's
retirement home in the sky or something at some point. So we need to
make sure that people are passing on knowledgeable information, accurate information, and stop
this social media people that just post stuff and they have literally no clue and
they don't back it up with code, They don't give any code references.
They want you to believe them, but they don't back it up with anything.
Okay, enough of that ranting. I held you in here for five
minutes ranting. So now let's get into the day's topic. So I was
asked the question, and this is going to be maybe difficult for me to
convey over a podcast. I have videos on this over on our fast Tracks
tube platform. We'd love to have you over there. It's a fifty percent
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We have an eight hour calculations video over there. I have a I
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great guy by the way. So that is all part of that annual
subscription to fast Tracks too, So give it a consideration. We'd prefer you
to if you're going to say thank you for what we do, I prefer
you to get into that because you get something for it, You get videos,
beautiful thing. Right. Okay, all right, let's get into today's
episode. So I've been asked by somebody to explain how to calculate for a
new restaurant in their case, it was an all electric restaurant. And how
to calculate the size of the service? Okay, which is also going to
apply to a feeder, right, because you could have the main service outside
and then it changes over into a feeder to come into the building. Okay,
same concept, But they want to know how do we calculate that?
Now? Typically I would calculate that using Part three, which is a standard
method and allows me to go through and collect all my things together, right
and just sizes it that way. But that would be an excessively large service
because I'm not going to have that much a demands that I can apply.
I mean, obviously I will for the receptacles at one hundred and eighty VA,
I will get a break on that. When you have a certain amount,
I will get some allowances, right, I will get some allowances for
non dwelling type of appliances. Okay, I will get some breaks for that.
But for the most part, I'm going to use something that is found
in the optional method. And just to let you know, for electrical exams,
the high probability is when they ask you about a restaurant calculation, They're
not going to throw all these things at you because you don't have enough time.
But what they'll throw with you is a total VA count that maybe have
done by the engineer, because typically restaurant's going to be designed by an engineering
firm. Right, They're gonna whether it's a chain restaurant, they're gonna have
these designs. They're gonna they're gonna be very specific about what they want because
this is not typically not a one off. They know what they're doing.
The design engineers know what they're doing, so they're probably gonna give you a
set via value voltampire's value okay, and you're gonna need to know okay,
and they may even give you all the load anyway, and all you got
to do is just follow directions on an exam. Typically, and I can
tell you this is the case in the Texas exam. What they try to
do here is just give you a total connected load. Okay, everything that's
been connected, so you haven't applied any demand yet. It's just everything just
added up. What is it. It's all the electric loads. That's the
heating and cooling, uh, that is the uh, every load that is
connected together. Okay, so all electric loads. Just add it all up
at its face value. And then you're able to then go to two twenty
dot eighty eight and you get to use the optional method. Now it'll tell
you right at the beginning of two twenty dot eighty eight, it'll say that
you can use this to twenty dot eighty eight in lieu of part three.
What that means is, it's okay to use this table, use this optional
method. But if you wanted to use part three, you could do it
if you wanted. Okay, So we're gonna be looking at what you're likely
to get on an exam, and that is the application of the optional method
under two twenty dot eighty eight. All right, So what you'll see here
is I'll read to twenty dot eighty eight, and then we'll give you an
example. It says calculations of a service or feeder load where the feeder serves
the total load. And it gave you that example whereas you may have the
main disconnect outside and then it turns over into a feeder coming in and hitting
the gear in stuff inside. That's an example where that feeder is going to
see the entire load of the restaurant. It's just simply allowing you to put
the equipment further into the building rather than outside or nearest point of entry.
You get me. So you might have the main disconnect outside could be rather
large, twelve hundred amp whatever, and then it changes over and you've got
feeders coming into the building. Okay, all right, So where that feeder
serves, the total load for a new restaurant shall be permitted in accordance with
Table two twenty eighty eight in lieu of Part three of this article. Okay,
so I don't have to do the piecemeal approach in part three. I
can just simply take up all of the electrical loads, and that includes both
the heating and cooling in order to come up with what we call the total
connected load. And a lot of the engineers will do that. They'll just
simply take all the loads that are in question. Right now, it goes
on to say the overload protection of these service conductors shall be in accordance with
two thirty ninety and two forty dot four. Well, of course two ninety
is saying each unngrounded service conductor shall have overload protection. So again you gotta
have your overload protection. You gotta protect your conductors. Uh. And so
that's so it's just should be a given. And then of course it's reference
to two forty dot four is just again reminding that you're going to protection of
the conductors, and then you'll have, you know, all these different allowances
like where you have overcurrent devices rated eight hundred amp years or less, and
then the next size up allowances, and then of course it'll remind you that
you have a situation where you have over eight hundred amps and you have overcurrent
protection and so you got to have all these rules that you have to meet.
Okay, that's all that's reminding you is remember you're gonna meet all the
general rules. It says feeder conductors shall not be required to be a greater
ampacity than the service conductors. If that makes sense. If these feeders are
coming from the service outside and the service conductors were calculated to be a certain
size, well there's no sense that there's no reason for those feeders inside that
are meeting this allowance. Again, remember that it has to what serve the
total load. Then this is just saying that no case does those feeder conductors
have to be larger than the service conductors. Okay, so you don't have
some weird situation where these feeders end up calculating larger than what the service conductors
would be. So the feeders again not required to be a greater apacity than
the service conductors. Makes sense. And then lastly it says service or feeder
conductors whose calculated load is determined by this optional calculation that we're getting ready to
do. It says shall be permitted to have the neutral load determined by two
twenty sixty one. Right six one uh for those that do know that actually
is in the optional excuse me, that's in the standard method. Right.
So again it's going to be one of those things that you're going to have
to do a calculation, and it sends you back to the two twenty dot
sixty one. But notice that it says that the service of feeder calculations whose
calculated load is determined by this optional method shall be permitted to have a neutral
load determined by two twenty dot sixty one. There are some applications where the
engineering and design is going to make it full size same as whatever these ungrounded
conductors would be, but you are permitted to use the allowances in two twenty
dot sixty one. Just remember that two twenty dot sixty one is under Part
three. So that means that where you saw that it said in lieu of
Part three, well, in order to calculate for the neutral, then you're
going to have to go back through and calculate that neutral, which is the
you're trying to determine the maximum unbalanced load. And since two twenty sixty one
sits in part three, it's not in part four. It's in Part three
that's going to force you to understand that you're gonna have to do what You're
gonna have to be able to do a standard calculation. So if anybody ever
tells you that you don't have to worry about how to do standard calcs in
part three, we call it standard, but it's just Part three method,
don't listen to them. You need to know how to even though your question
might be on the optional method, you need to understand how to do the
regular method under part three. Now, good news for most electrical exams.
When they give you a total connected load, they don't give you all of
the variables in order to be able to calculate the size of a neutral load.
So that means you don't have to consider it, you're only sizing.
Maybe it wants to know what the size of the service. It's not asking
you for the neutral okay, so again that makes it easy for that.
But in the real world, just remember that you can use this optional method,
but when it comes to the neutral um you you would you can use
the two twenty sixty one, which is under Part three, which means you're
going to have to do a standardized calculation. But this is permitted. It
says it shall be permitted if you want it to be full size neutrals based
on the size of your ungrounded conductors that you're going to do in this optional
calc You can do that if you want, and it's just going to be
bigger neutral conductors. But that's never going to hurt anything. Okay, all
right, hopefully I'm clear with that. All right, So let's look in
an example. Lets so let's say in our example, let's say that the
engineer gives me or the exam says that you have six hundred kVA of total
connected load. Then that's they're giving me that. They're telling me, okay,
we'd added everything up. We've already done all this. We're to added
all the ace, see any heat, we took, all the electric loads,
we added everything up and it is six hundred kVA, and that's what
it gives you on the question. So now you're saying, Okay, how
the crap do I apply this this table for that? Okay, well,
let's look at the table and let's work it together. So when you come
down to this table, to twenty dot eighty eight, and again, if
you're out in the field driving, just listen, and when you get somewhere
take a break, crack your codebook open and go to twenty dot eighty eight
and look at the table. On the table, you'll see three columns.
The left cottumn is your total connected load, which is what the engineer or
the exam gave you. It said six hundred v eight Okay, six hundred
kVA. Okay, that's your total connected load. They just gave it to
you. They've already done the work for you. Now. In the middle
column it says all electric restaurant. That's what we have. In the right
it says not all electric restaurant. So that means you might have, for
example, some gas Okay, you might have some gas appliances and whatnot.
So in our case, most of the time, the questions that I'm aware
of on the electric exams, deal with an all electric restaurant. Okay,
Now, it's not gonna matter for you on the exam, because whether they
say it's all electric or not, they're still going to give you the total
connected load. You just choose which one they have to tell you whether it's
an all electric or if it's not all electric. And the only way that
you'd be able to tell is that they gave you a list of certain things
and ended up saying in there that was a gas range or a gas this
or what. Then you should look at and go, well, crap,
it's not an all electric restaurant. And that's okay. There's still use the
VA that they gave you, and you just choose which column to use.
Now, in my experience, most of the time the questions are based around
an all electric restaurant, but just be ready to based on what they give
you. They may get give you a sentence that says electric all electric restaurant
with gas cooking or whatever. Then you they're trying to They're not trying to
trick you. They're just making you think, well, wait a minute,
it isn't an all electric, and that's why you have the other column and
you apply the code the same way I'm going to do it here, but
I just want you to be aware of that so you don't get tripped up
by anything. All right. So in our case, it's an all electric
restaurant, So we're going to be using the total connect the load column,
and we're going to be using the center column, which is all electric restaurant.
All right. So now we had six hundred kVA, So on the
left, you'll notice that it goes zero to two hundred, then it goes
two hundred and one to three twenty five. And remember that is kVA,
So that is two hundred thousand zero to two hundred thousand va, and then
it's two hundred and one thousand to three hundred and twenty five thousand, and
then you have three hundred and twenty six thousand to eight hundred thousand, and
then you got over eight hundred thousand. Okay, you see, we're we're
doing all this, okay. So now the first thing we're gonna know is
which one are we in? Where we're in the one that's three twenty six
to eight hundred, right, because the engineer gave us or the exam gave
us six hundred kVA. Perfect. So now we go to the right and
we go to the center. Calm, no, what does it say.
It says fifty percent. Now, the first thing that people do in mistakedly
is they take that six hundred kVA and they drop it to three hundred.
They think that's what this means. That is not what this means. Notice
the order of working out of an equation. You do the parentheses, and
you pay attention to parentheses first. And here's what it says. It says
amount that's over three twenty five, and that is what the fifty percent is
applied to. So if we have six hundred, we have to take away
three twenty five, so the amount over three twenty five. So I'm gonna
have six hundred and I'm gonna take away three hundred and twenty five. That
gives me two hundred and seventy five kVA. Okay, So now what it
says is take that amount at fifty percent. So I'm going to take that
two seventy five and I'm going to multiply that by point five zero, and
that gives me one hundred and thirty five point five. And if you question
your math, just do that times two, and you'll see that takes you
back to two seventy five. Okay, So now that I have one hundred
and thirty five point five, then I'm going to actually finish the equation.
It says then it says plus one hundred and seventy two point five. So
I'm going to take that one thirty five point five plus one seventy two point
five, and that's going to be three hundred and eight kVA. That is
now my calculated kVA, and I use that now to multiply that buy whether
it's single phase or three phase, in order to to find out what my
conductors need to be. Okay, but this is the kind of question that
you'll get on an exam, and you need to make sure you understand how
to do this. Okay. For example, if this was single phase,
then it would be three hundred and eight, right, and so me at
this point, I like to actually go and make it all the way three
hundred and eight thousand, uh, And then I divide that by two forty
and that is one thousand, two hundred and eighty three point three, and
that is my AMP rating. So I'm going to be one thousand, two
utter and eighty three, and then of course for me, I need to
parallel that out so that I can see how many sets I need to be
in order to be able to cover that one thousand two uter in eighty three.
Okay, Now, if this was three phase, then you got to
remember that it's the square root of three is one point seventy three to two.
So I'm going to be taking what I'm going to be taking that three
hundred and eight thousand. Now, well, first of all, let's go
in and get our value for the square that we're going to use in here.
So it would be it would be two eight times one point seven three
to two, and that would be three hundred and sixty point two five six.
So we're gonna make this three hundred and sixty point two six. And
now we're going to take that three hundred and eight thousand divided by three sixty
point twenty six, and now is going to be eight hundred and fifty four
thousand, excuse me, eight hundred and fifty four point nine three eight,
which is going to translate this into eight hundred and fifty five. So we
have eight hundred and fifty five amps, considerably less than if it was single
phase. Which was twelve hundred. So again inherently, you see there are
benefits in this case to the three phase. So I'm going to still do
the same thing, and then at that point I'm going to have to determine
how many sets I need in in this case, the other one, I'm
might have needed four, and this one it might only need three or maybe
even two, depending But that all depends again on what you're what you're dealing
with, whether it's three phase or single phase. And they have to give
you that in the question, by the way, Okay, it's not something
that you have to just you know, God, I wonder what it is
they're going to give you this information. So this is the kind of question
that you'll see, for example one a Texas exam, And you just need
to be able to understand how this works. And I think the more important
part is how the column works. Remember in the center column when it's all
electric, it's telling you that the fifty percent is applied to the amount that's
over three twenty five, and then you add the one hundred and seventy two
point five to that to get your total calculated load. Okay, and that
is no different if it's not an all electric range, same kind of concept.
It's just the percentage values change. So hopefully that that's made it a
little easier. Maybe. I know it's a podcast, so it's kind of
difficult, but if you pause it, you follow along. And I sometimes
take a lot of pride in making sure that I'm painting a mental picture.
But sometimes, you know, I can struggle with that because so you know,
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right, all right, so hopefully I explain that to you you got a
little better understanding of it, and I did in confuse you. But if
you do you have any confusion, you know what you can do. Just
go to Paul Abernathy dot com send me your question. Be very detailed about
what you don't understand. Let me know what code cycle you're under in the
very again, very detailed in your question, because it's hard for me to
answer vague questions, so please be as detailed as possible. Until next time,
folks, stay safe, God bless