What Up? What Up? Everybody? 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. Dude, we get
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have that's been slated for me is oh, and I should remind you if
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you remember, please let us know prior to it your question in the comment,
so that we know that yours can be elevated. That's the first thing
that she looks for, all right, So the very first one we have
that she's got slated for me. It says Paul from the twenty twenty three
code. I have a gutter being fed from a panel ten feet below with
one inch emt okay, So mental picture, folks. They has a gutter.
It's being fed from a panel below it, so it's basically a trade
size one EMT running up to feed the gutter. Okay, it says,
I have a ground bus in the gutter, trying to limit how many grounds
are in the panel. Do I need to ground? Do I need a
ground in each conduit? If there is no chance of the conduit being broken
open and a junction box being added between the gutter and the panels, so
there's nothing they can guarantee that there's nothing that's going to be installed between the
gutter and the panel. I don't not sure how you guarantee that, but
okay, so it says, thank you for your work and your podcast.
All right, I appreciate that question. So this is kind of a twofold
question here. Equipment grounding conductors are required for every brand circuit. Okay,
However, there are some allowances In two fifty two. It talks about when
you have multiple circuits. So if you got your codebook, and those that
do listen to this podcast and do break out their codebook, you would be
looking at two f two c C talks about multiple circuits. So it says
a single equipment ground of conductor shall be permitted to be installed for multiple circuits
that are installed in the same raceway, cable trench, or cable tray.
It shall be sized from table two fifty one two with the largest overcurrent device
protecting circuit conductors in the raceway, cable trench or cable tray. Okay,
all right, So then the rest of the part that has to do with
cable trays so that we're not gonna worry about it. Okay. So here's
the thing. When you run that raceway up to that gutter, and you're
gonna run multiple branch circuits in it, then you could run one single equipment
grounding conductor up there, okay, and it's sized based on whatever the largest
overcurrent device is that's protecting the circuits that are in that raceway. Okay,
So you could you know, if it's a if it's a sixty amp is
the largest one, right, then you go to two fifty sixty six and
size the equipment grounding conductor for that. And again, if it's sixty,
then it's Coppered's ten gage. So that's the largest you'd need. And so
if all the other circuits that are in that raceway are smaller, then the
ten is already larger, so it's perfectly fine. If it's a thirty amp,
then it's still going to be a ten. If it's a twenty amp,
it'd be a twelve. So the tin is larger than the twelve,
so you'd be fine. That's under that provision. Now if you have separate
raceways that are supplying that gutter, which you kind of you know, didn't
allude that the way your question is you you basically said you only had one
trade size one EMT going up. And if that's the case, then you
are allowed to take one properly size for the largest overcurrent protective device and do
that. Now. I will remind you something since you're already designing this is
that, since you're running EMTs, an EMT in two fifty eighteen is already
listed as a type of equipment ground and conductor. In fact, if you
go look at it, and we're in the twenty twenty three edition of the
NEEC always unless stated otherwise, or the latest edition. If you go look
at two fifty, don't one eighteen A four it says electrical metallic tubing.
So you don't have to put a wire type equipment ground a conductor in that
if you don't want to. Now most engineers will speck it out. I
get it. Just remember that you could use the EMT as your equipment ground
and that would essentially if you ran extra raceways, that would eliminate you having
to put the equipment ground of the wire type in any of those raceways,
as long as everything is bonded together properly, right, follow all the rules
for bonding Part five. So, but remember if you decide to put a
wire type equipment ground in even though the EMT qualifies, if you decide to
put the wire type in, guess what, you still have to size it
properly. You get no break for undersizing the wire type if there's a EMT
for example. So a lot of people get that wrong. They think,
well, the EMT is there, if I put an equipment ground in of
the wire type, then it can be smaller than what's required by Table two
fifty one twenty two. That is false. Okay, if you're going to
put a wire type equipment ground in there and you're not going to be using
the EMT. For example, is your low impedance effective ground fault current path
which is permitted in the code and listed under again ten A four. You
still if you put the wire in, it still has to be properly sized,
so that's like a two fer. That's another myth that people tend to
think that you don't. Your best bet is to just not put the wire
type in. And it pains me to say that, but your best bet
is to not put the wire type in and just use the EMT and to
make sure you do everything properly. If you're trying to reduce the number of
equipment grounds, okay, if that's your sole goal in doing that, then
that would be you know, that's something that you could do. Okay,
all right, hopefully that answered your question. Obviously, If anybody's listening to
this episode and there's additional clarity that you need, you know what you can
do. All you have to do is take note of this episode number and
go to Paul Abernathy dot com and submit something in the portal. Give me
a summary of what you're asking, let me know what it pertains to in
the podcast if you're listening to it, so that I don't have to go
back and re listen, because I'm not gonna do that and ask your question.
And I'm more than happy to elaborate on it. I'll go into more
detail. Obviously, in a podcast, I can't cover every possible scenario.
And there's always a smart attic out there who wants to bring up the obvious
something that we may not have covered because they have nothing better to do in
their life but critique and never create anything original on their own. So I
get it, and it's okay. I don't mind it. It doesn't bother
me at all. All right, Let's go on to another question that was
submitted. All right, So that was a good question, So let's move
on to another question. All right. This one was submitted through the portal,
and it is Hello. Hello. First of all, thank you for
the podcast. You're most welcome, and thank you to everybody out there that
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I challenge you today go back and listen to some of the older episodes,
and if you've got any questions on them, remember just jot down the episode,
give me a brief summary, and ask your of the episode. Then
ask your question and post it over on Paul Abernathy dot com. I'd love
to relive some of the old episodes, all right, So this question says
hello, First of all, thank you for the podcast. You've helped me
pass to residential licensing exams and a journeyman exam. WHOA, there you go.
Congratulations. We love to see it, I believe it or not.
I do live vicariously through my students and people that I associate with, and
I love to see success stories. I love it. He goes on to
say, it's the twenty twenty three code and he's in Oregon. Okay,
so up in Oregon, all right, So he's asking a question, he
says in two twenty five thirty nine, D. It says for all other
installations, it says the feeder or brand circuit disconnecting means shall have a rating
of not less than sixty ampiers. Is this code saying that the feeder is
required to be a minimum of sixty ampiers or just the disconnect? Okay,
good question. So what we want to do is we want to go over
to two twenty five. I've got thirty nine D, and I remind folks
that this is going to be very similar, okay for what you would do
over in two thirty as well. Okay for those that wonder. So if
you if you're familiar with how to apply two thirty dot seventy nine, which
is the rating of the service disconnecting means, then this will be old hat
for you. Okay, all right, so let's kind of go look at
it. I'm going to go to two twenty five and go to thirty nine
D and thirty nine D on the first thing you want to notice because in
your question you're asking does this apply to the minimum sizing or the feeder or
this applied to the disconnect? Well, the title of it is two twenty
five thirty nine rating of the disconnect Okay, so that's the that's the first
part you see in that it says the rating of the disconnect. Okay,
so obviously we're talking about the disconnect rating as well. Okay, So my
response to this would be, look in two twenty five dot thirty, it's
referencing the number of supplies that you can have to a detached structure. Okay,
so much like two thirty dot two does for services, So we can
have multiples right now, at the end of the day. The basic rule,
right is that you can have only one branch or one feeder to a
building, but there are some allowances, right that can let you have more.
So now the question really is in this one, it's like, okay,
Paul, does this apply to the circuit or does this apply to just
the disconnecting means. So let's read what it says in two twenty five thirty
nine. It says, and I think it almost went down a different rabbit
hole there, but that's a whole different question about the number of services or
the number of brand circuits or feeders to a building. That's probably another episode.
Anyway, it says a feeder or brand circuit disconnecting means shall have a
rating of not less than the calculated load to be supplied. So that's the
first part of it. So if I've got this detached structure, right,
and that's what two twenty five is, it's obviously outside brands or feeder,
so it's got to leave the dwelling or it's leaving the building. It's going
to what it's going to another structure or another building. Those are defined terms
in the NEC and it's saying, okay, well, if feeder or brand
circuit, then first things first, the feeder the disconnect has to be sized
based on what the load that's being served. Okay, so that's the first
part. And how do you determine that? It says in accordance with Part
one or Part two of Article two twenty for brand circuits. Then also if
you're talking about for feeders, then you're going to use Part three or Part
four standard we'd call the standard or the optional method. Okay for that.
Now again it says where the brand circuit or feeder disconnecting means consists of more
than one switch or circuit breaker as permitted into twenty five dot thirty three,
which means you could have up to six grouped in the same location. Right.
Then it says combining the ratings of all the switches or circuit breakers for
determining the rating of the disconnecting means shall be permitted. That's important, okay.
And it says in no case shall the rating be lower than specified in
two twenty five thirty nine A, B, C or D. Okay.
So the first thing is one, we have to calculate the load to the
building, and you're going to size everything according to that load. Right.
The disconnecting means can be made up of multiple switches of multiple circuit breakers.
So unlike with services, where used to be that in a single enclosure you
could have a six disconnect rule. Were that went away, Okay, you
can't have in a single enclosure. You can't have six disconect rules for the
service, but you still can do that for the feeder. Why is that
because you're able to shut it off upstream, so there's no hazard at those
lugs because you could shut it off, So that six disconnect rule doesn't apply
to the feeder. That applies to the service. Okay. So first point,
So I could have up to six switches of circuit breakers. Okay,
So that's important to remember, Okay, or I could have just one.
So when you look at ABC and D, okay, number one or A
is one circuit installation. Okay, So this is obviously one for brand circuit.
So if I had a detached structure we're building, it's okay to for
the installation of supply only limited loads of a single brand circuit. The brand
circuit disconnecting means shall have a rating of not less than fifteen ampiers. So
this is an example where I might feed a detached structure just maybe it's a
garage, and I would simply feed it and put it on. If it's
a brand circuit, I might hit something as simple as a snap switch that's
rated fifteen ampiers. That's my disconnecting means. That's it. I'm not putting
a panel in. I'm just putting a brand circuit in. And we already
had that allowance in the code for being able to run a single branch circuit
to a detached structure in Okay, So that's what we did, and so
fifteen amps would be perfectly fine for that. The next one was b It
says, well, two circuit installations all right, says for installations consisting of
not more than two two wire branch circuits. The feeder or brand circuit disconnecting
means shall have a rating of not less than thirty ampiers. So thirty is
the minimum threshold. I could have not more than two separate circuits running to
the building. Okay, all right, so again in this case the disconnecting
means, should I have a rating not less than thirty amps Here's interesting though,
remember what we saw earlier about they could have up to six in the
same enclosure. This would qualify me if I had a panel and I had
two circuit breakers in each one was rated fifteen ampiers. Right, fifteen and
fifteen is thirty. That's what that meant in that charging statement. Okay,
let's go on. So the next one would be a one family dwelling.
For a one family dwelling, the feeder disconnecting means. And this is an
example where you might be coming in and now you're let's say your service is
in a garage. And this is a unique situation, and I've done a
few of these. The service to the house is actually in the detached garage,
and then it's a feeder that's leaving the garage in supplying power to the
dwelling unit. Okay. If that's the case, then you would be using
C And it says for a one family dwelling, the feeder disconnecting means,
shall I have a rating of not less than one hundred ampiers. Now that
is very consistent with what we saw in two thirty seventy nine. Okay,
so at least one hundred. Now interesting here is if it's a feeder to
that dwelling, then I could still utilize the six disconnect rule. I just
can't do that in a single enclosure in a service. Okay. Now,
don't get disconfused with the ability to have six separate enclosures, because that's still
allowed for services. And okay, so don't get confused. Don't let the
mind start wandering all over the place. And then the last one is all
others. Now, this applies to all others that's not covered here, and
it says for all other installations, the feeder or brand circuit disconnecting means shall
have it rating of not less than sixty ampiers. Okay, So think about
it this way. Sixty is the minimum size for your disconnecting means, but
you have to size everything based on what a load calculation you have to service
the load at that structure. Okay, but in all cases, the disconnecting
means, the rating of the disconnecting means cannot be what cannot be less than
sixty ampiers. So you're going to be sizing your conductors based on your load,
right, and you're gonna be protecting that feeder at its opacity by the
breaker that's supplying that feeder, right. So all this is is a disconnecting
means at that detached structure. That feeder is or is already protected. So
there we're just talking disconnecting means. So you've already sized your conductors based on
the calculated load. You've already sized your overcurrent device to protec that conductor that's
the feeder, and now we're just talking about the disconnecting means that is in
that detached structure. And this tells you that if it's not a B or
C, then it cannot be what it cannot be less than sixty amps.
Could it be more than that, yes, but it can't be less than
sixty amps. You with me, Okay? All right, hopefully that answered
your question on that one great question. By the way, I love getting
these questions, and I think we've done twenty one minutes in this recording.
I think we have time for one more, So we're gonna get one more
into this episode here. So let me look for that for you, all
right, So let's pick it on up here to the next question that was
submitted, and I'm gonna remind you folks again. All you got to do
is go to Paul Abernathy dot com. Dude, it's free, doesn't cost
you anything to submit questions to me. So this question says, I have
a question about available fault current. Okay, so questions about available fault current.
It says I recently had a contractor perform a calculation on a new one
hundred amp service for a digital billboard. Okay. It says the calculation came
out to ten thousand and seventy amps. It says the main breaker has an
interrupted rating of twenty two thousand amps. The brand circuit feeder breakers have a
ten thousand amp rating. Is this installation compliant because of the twenty two k
AIC rating? Or is the rating of the entire panel board ten k because
the lowest installed value on the branch circuit breaker? Great question? Okay,
great question, So let me answer this. Now, this individual I have
emailed back. I already gave them a response. Okay, so I'll elaborate
here, read you my response so that you kind of can get a feel
of this I put you know, the panel in question, is that panel?
The first thing you have to look at is that a series rated panel
and is it marked as such. If that is the case, then the
main would permit lower values onto the circuit breakers installed in that entire enclosure in
cabinet. So the first thing that you need to do is you need to
go look and see whether or not it's stated in the legend whether it is
a series rated panel board. Okay. Now, in those series rated systems,
the upstream device effectively reduces the ai C okay to the downstream device.
That's the whole process of it being series rated and evaluated as such. However,
this is not the case if it is not series rated. That's important.
So if it is not series rated, then what happens. Well,
if you have a panel that it is not series rated, then the circuit
breakers that are limited to ten K must not be exposed to a value that
will do what exceed ten K. So important to remember now, in a
series rated enclosure. Everything that gets done. Then it's designed to have a
main breaker rating and it's designed to have other overcurrent devices that are installed on
the bus. Okay, that's how they're designed. That's what the series rating
is. Now, one of the things that I'll direct you to is two
forty eight six B and I'm in the twenty three edition of the e NEC.
It talks about the testing and the series ratings of panel boards and such,
and will also have an informational note which direct reshe to one ten dot
twenty two as well, and more specifically it talks about one ten dot twenty
two C. So if the if it is series rated and it is listed
in marked as such, then you're good to go, right, no problem.
If it's not marked series rated, then you must ensure that the AAI
C that it's going to be imposed onto those devices that have a lower AIC
rating are not exceeded. So that's important thing. Now, where could this
come into play? Okay, So this could come into play where I have
a panel with a main breaker only and then I have a panel right next
to it and we don't have any series ratings going on. Then you could
have the potential and This is something we talked about earlier when it was talking
about SPDEs and that ten kai c that was that they wanted to get rid
of, and some of the manufacturers said no, no, no, no
no, because depending on its proximity, it could see available fault current that
is higher than that. So it's important that it has a minimum rating correct.
So in this case, if you don't have any series rating is involved,
and your AIC rating is going to potentially exceed the rating of a device,
then that would be a problem, okay. But in a series rating
equipment and how that's installed, if you have a main breaker that's twenty two
KIC and you have a circuit breaker that's installed on the bus that's associated with
that breaker, and they are series rated, then it would be okay for
that ten KIC circuit breaker to be installed on in that bust because that whole
thing has been listed and it's all been evaluated as a series rating. So
make sure you check that out in your panel. Hey, do yourself a
favor, folks, go out to your panel right now if you're an electrician,
and open it up. Be careful and look at and see as is
your current panel series rated, and let us know over on Paul abernaty dot
com or in the comments to these videos or this podcast. I should say,
all right, folks, that's all I've got for this episode. I
appreciate everybody that listened to the podcast. Remember we still have a bunch of
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We will customize these. We have some great blogs. Make sure you download
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link. Until then, if you've got any questions, do me a favor.
Go to Paul abernaty dot com. Till next time, Stay say folks,
God bless mask. Nohing do