What Up? What Up? Everybody? Welcome to another episode and let's ask
Paul. My name is Paul Abernathy, your host for the podcast. Thanks
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ask PAULS. I guess I should say today's episode is sponsored by I guess
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you to go check that out. All right, let's answer some questions here
that have been submitted, and as I've told you, I am trying my
best to catch up. I have got literally so many of these things that
I can't count, and sadly I work for most recent backwards. So some
of you that are the old ones you're having to wait, because again it
doesn't sort them for me. I'm just kind of hitting them as I go,
and so again just bear with me. I will get to you,
all right. Question is, hello, Paul, I have a question regarding
the grounding of e MT. If I'm going from the main service panel into
an in phase solar inverter. So this is a micro inverters in phase makes
those. They were the first ones to make those. I think other ones
now license their design, but they were the first ones micro inverters. So
I'm going to these micro inverters, which they stayed are made out of plastic.
Do I need to use two ground bushings on both entrances or am I
good with just ground bushings on the main service panel side? Thank you,
Thank you for your awesome and informative podcast. Okay, well, thank you
for the question. Now it sounds like since these are micro inverters, these
are just branch circuits going out to these microinverters. So I think that when
it comes to the bonding them, if one in is like just open and
you bond one end, then you're actually bonding the raceway. I think it's
fine. You're not using this to enclose a grounding electrode conductor because these are
still brand circuits, so you have an equipment ground in it that type of
thing. Now, what would be different is if you were using the EMT
as an equipment ground and again you're stopping at one end, then if you're
using the EMT as an equipment ground, then you're going to need to continue
it over to the connection point that maybe on the micronverter. So it's going
to depend on how you're running the system. But if it's got an equipment
ground in there, and you're running it to the micro inverter and you ran
an equipment ground, then really all you're doing with the EMT is bonding it,
and you're doing that at one end, and that's considered adequate for this
scenario. Okay, Again, you're not using this raceway as the enclosure for
a grounding electrode conductor where it would require you to bond both ends and those
type of scenarios, so no problem involved in there. And again we don't
have any other detail on what you may be doing at the other end,
whether you're putting a junction box and then coming out of the junction box over
to whatever your microverters may be. So if that's the case, your equipment
grounding conductor is going to be bonding that box as well at the end of
that EMT. So it's the best I can gather from what you're what you're
stating, so I would think that you're fine on on the the end that's
connected to the service. And again I would assume that you, since you
don't really state that it's a complete system, that you probably are running an
equipment grounding conductor with the circuits up to you, you know, from your
in phase micro inverter. I'm assuming that's what you're doing. If not,
please feel free to clarify and re send something back and I will go into
more detail if necessary. Okay, all right, let's go on to another
question that was submitted. It's says, hello, sir, can you clarify
this for me? I believe article three ten fifteen C one D and I
believe that section three ten fifteen C one D one through four. Tell me
I can have ten twelve two MC cables bundled without derating. My inspector says,
MC cable is like conduit. Once you have more than three current carrying
conductors, you have to d rate. Thanks Paul. Okay, let's tackle
this question. This does come up from time to time when people are talking
about doing an adjustment. Now, remember when we say de rating, we're
lumping a lot in that because d rating is not something that's in the NEC.
It doesn't say de rating. It says adjustment or correction. So when
we're doing an adjustment, we're doing an adjustment for the number of current carrying
conductors that exceed three. And when we're doing a U temperature correction, that's
about an ambient temperature application, right. So in this case, what they're
referencing is in three ten fifteen C one, So this is where you have
more than three current current conductors. So we're going to kind of read this
and uh and break this out. But the one that they're really focusing on
is D and I am looking at the twenty twenty three edition of the Nasometrical
Code. In case you're following along, I'm going to read you the entire
part of C one so they can kind of get the context of what we're
talking about, and then we'll shift to the MC, which is the question
in hand. Now. C one says more than three current car conductor says
the apacity of each conductor shall be reduced as shown in table three ten fifteen
C one, And that is the actual table, folks, where you have
four to six, seven to nine. You know that type of thing,
and you get a percentage that you're going to have in a multiplier. Okay,
it says where the number of current car and conductors in a raceway or
cable exceed three. Now these are twelve two's, so keep that in mind.
Or were single conductors or multi conductor cables not installed in a raceway?
So these MC cables one are not raceways, they're cables. So that's with
inspectors are a little off there, and I think I know what they're trying
to say, but cables are not raceways right right, are installed without maintaining
spacing for continuous length longer than twenty four inches. And then it says each
current current conductor of a parallel set of conductors shall be counted as current carent
conductors. Right, So if you have a raceway with two sets of five
hundred kc MIL, then two of the phase A, two of the phase
B, two of the phase C for example, all of those are considered
current carr and conductors even though they're in parallel. Right, So phase A
would have two current carr and conductors, Phase B would have two current caring
conductors, Face C would have two current carrying conductors. And it could be
possible that the grounded neutral conductor is a current caring conductor. But that's for
a whole other episode. So let's kind of dig into this a little bit.
So it goes on to say, where conductors of different systems as provided
in three hundred dot three are installed in a common raceway or cable, it
just reminds us that the adjustment factors shown in three ten fifteen C one,
which is the table, shall apply only to the power and the lighting conductors,
not to the control. Okay, so it's not going to apply to
those zero to ten control type of conductors, only to the power and lighting
that you would have this apply. Now, if you go down, you're
going to see that there's an A A B, A C A d uh
in this application, and so we're going to be focusing on D now.
D says, Okay, look, I get the rule we just talked about.
It says, I get it that if you have these MC cables and
they're bundled and all this, that you've got to do something if it's more
than three current car conductors. But here's what it says. It says the
adjustment factors shall not apply to type AC cable or type MC cable under the
following conditions. So you have to meet these conditions, and if you do,
then you can ignore Table three ten fifteen C one. You can just
ignore it. Now, I'll remind you folks, you can't ignore the correction
for ambient temperature. This is only to ignore the adjustment factor for where you
may have more than three current carr and conductors or bundling involved for MC cable
or AC cable. Hey, I think it's important. Remember you could be
installing it in an area inside of a building where you have an elevated to
ambient temperature and you're not gonna apply the adjustment factor for the number of current
carent conductors because of this allowance. But you still have an ambient temperature that
you have to take into consideration, and that would be three ten fifteen B
one one. Okay, So I just want to make that clear. This
is only giving you a bit of a reprieve when it comes to adjustment factors
for AC or MC cable. Now let's look at these conditions. So in
order to be able to ignore Table three ten fifteen C one for MC and
AC cable, number one to cable do not have an overall outer jacket,
so no PBC extruded covering. Okay, So it's not gonna hold in the
heat. Okay, it's gonna allow those conductors to heat, and it's gonna
allow the armor to act as a radiant to help dissipate out the heat.
Okay, fine, it's not covered any outer jacket number two. Each cable
has not more than three current carrying conductors. Now, in our example,
the gentleman said it was a twelve to two MC. So it's going to
have twelve two black and a white. It's going to have an equipment ground
which could be bear or insulated, depends on the manufacturer. The standard UL
fifteen sixty nine allows either. Most of US manufacturers will go on and do
an insulated equipment ground because there's other aspects of the code where we want it
to be insulated. So it just saves in production. But the standard would
allow us to do it bear or insulated. In fact, when you get
larger MC, I mean the bigger stuff, you know the four ought,
the five hundred kc mil two fifty k, then typically we just go on
and use a bear equipment ground. And that's perfectly okay, right aightem Number
one permits it to be bear covered or insulated, so it ends up being
a manufacturer's preference in how they want to produce it, right, Okay,
So in this case, we don't have more than three current current conductors,
so this guy does not. And then the next one is item three.
It says the conductors are twelve awg copper, so this only applies that the
conductors are twelve and like they said in their question, it was ten twelve
two MC cables. Okay, fine, and then it says number four says
not more than twenty current carrent conductors are installed without maintaining spacing, are stacked
or supported on bridal rings, so they're all kind of bundled together. Okay,
So how many do we have? So if we have ten twelve two
MC cables mc metal clad, then the only two conductors in this that are
current carrying is the black and the white. Okay, So that neutral conductor
is considered a current carrying because what goes out has come back in theory,
okay, kind of the you know how it works, And so the white
is considered in this case in a twelve to two a current carring conductor.
So since there's ten of them, so it's just ten times two and that
is twenty current care and conductors. Now we don't count the equipment ground as
a current carent conductor. And where do we get that language? Well,
that language to us comes in F. If you just scroll down a little
bit, then you're looking at three ten dot fifteen and you're going down to
F. It says grounding and bonding conductors. It says grounding and bonding conductors
shall not be counted when applying the provisions of three ten fifteen C. One.
So we rule that out. So only thing we've got is the blacks
and the whites in this one, and so that's twenty overall current carr and
conductors. Right, So going back up here, it looks like we meet
item number one in D. It looks like we meet item number two,
number three, they're all twelve gage and number four. There's not more than
twenty. We have twenty. We don't have twenty one, which would be
more than twenty. We've got twenty. So in this scenario, we are
done. So to answer your question, you do not have to take into
account any adjustment factors due to this bundling, because you're utilizing the allowance in
three ten fifteen C. One D as you so accurately stated in your question.
So your boss or your inspector is incorrect. Now, there is a
provision, folks where you can have an exception. If you have more than
twenty, you still have to meet D one, two and three. But
four says, you know what if you meet all of the others, but
you end up having more than twenty current car conductors, well, then what
we're gonna do is we're going to let you use a sixty percent adjustment factor.
And so again, ultimately be honest with you, that's gonna end up
being a situation where your twelve gauge is not worth twenty amps anymore because of
this adjustment, and that's probably not what you're gonna do. So the thing
you want to do is, if you're gonna bundle, make sure you separate
these out and that you don't exceed more than twenty current carring conductors in any
bundle application, whether it's on bridle rings or you're installing them in a tray
or whatever you're doing. Okay, And so it's really it's about your design
and doing a little care up front in how you run your design. But
that again, that's that's quite a few mc cables bundled together, and you're
able to simply ignore an adjustment factor in this scenario if you meet all the
caveats in D one, D two, dot three, excuse me, D
one, D two, D three, and D four of three ten fifteen
C one makes sense. Okay, So that answers that question. So you
are absolutely right. Your inspector is incorrect in this application, and based on
everything that you've given to me, I think you're you're perfectly okay. Again,
don't forget about ambient temperatures, but as far as the adjustment part of
it factors, then I think you're okay. Okay, let's see here.
We got another question that we'll try to tackle, and let's see if we
can get this here. It says Hi Paul, I'm getting conflicting answers on
this and would like you to weigh in. Says I have a one and
a quarter rigid threaded close nipple that is entering into a concentric knockout on a
meter socket. Okay. Says this nipple carries feeders, two phase conductor connectors.
I think you meant conductors, and a grounded conductor and an equipment grounded
conductor from the load side of the main overcurre protective device to a basement subpanel.
My question is do I need a bonding bushing installed on this nipple as
it enters the meter socket. Now there's a couple of things I'm gonna have
to point out here because this is where a question can get very confusing,
and I'm gonna explain why. So the listener is going to get the best
that I can give them here because I've got two different things going on here.
And if you've listened to me before, you know what I'm talking about
here, and I'm going to read the last part it says this is a
residential service with the voltage that is less than two hundred and fift volts to
ground. Enjoy your podcast. Thanks, okay, thank you for listening to
the podcast. So we got a couple of things going on. First of
all, you said that it's going from the meter socket, so that tells
me that those are service conductors. But then you go on to say the
nipple carries the feeders, which is two phase conductors, a ground a conductor
and an equipment grounding conductor, which tells me it can't be the service But
then at the end, you end up saying that it's for the load side
of the main overcurrent protected device to the basement subpanel, which again brings me
back to sounding like it's a feeder. So I am confused. So the
easiest thing for me to do is just give you the code rule, and
you determine whether or not you're dealing with service conductors or you're dealing with fears.
How about that? Okay, So now if you're dealing with service conductors,
you're going to be in two fifty ninety two. There's an A and
there's a B, and A just kind of reminds us that those normally non
current carrying metal parts, okay, have to all be bonded together, and
that is raceways. And your nipple is a raceway. They just short one,
but it is a raceway and it contained if it contains service conductors,
then again all of those non current carrying metal parts have to be bonded together.
Now, one of the things about that is you end up getting into
b which says, okay, well, how do I do that? How
do I method of bonding at the service. So if you have concentric or
eccentric KOs, okay, and I believe you stated you do, then let's
read what it says. It says bonding jumpers meeting the requirements of this article
shall be used around impaired connections, such as reducing washers or oversized concentric or
eccentric KOs. Standard lock nuts or bushings shall not be the only means for
bonding required by this section, but shall be permitted to be installed to make
a mechanical connection of the race ways, so mechanically connecting everything together. The
locknuts are fine, but you can't rely on standard lock nuts in order to
make that what we used to call kind of an assured bonding application. So
if you have concentric or eccentric KOs, then what it's going to tell me
is that you're going to need a bonding jumper. Okay, So that's what
it says, and be if you're dealing with service conductors. Okay, so
that's the first part. Now, if you're not encountering a concentric or eccentric
KO right in that scenario, it's just a punch hole. You punch it
yourself. Then there are other means, other things that you can use,
like bonding type block nuts, you know, things like that. So there
are other methods that you can do here. You may have a hub that
you're going into or something like that. But if you're encountering an impairments such
as centric KOs or even a reducing washer. By the way, if you
were to do a reducing washer and for tholkse that don't know, when you
have those KOs and you're gonna, let's say, do a reducing washer,
you need to remove all of the rings. That's what those reducing washers are
design. They're not designed to work with the rings. They're designed to work
without the rings. And so you use the reducing washer and they go in
place of the rings. Even then that's still an impairment as far as this
rule I just read to you, and you're going to need a bonding jumper.
Now again, if you happen to come in and you're not dealing with
any of those impairments right then what you'd be utilizing is other options. And
before has other options like other listed devices such as again bonding type locknut bonding
you know the bushings, bushings with bonding jumpers. Okay, those laning like
you have other options, but again you can't use standard locknuts only from mechanical
and if you encounter concentric, eccentric, or oversized knockouts, then electrical continuity
must be ensured, and you need to install a bonding jumper. And this
is going to be a supply side bonding jumper because that's on the service side,
the line side. Okay, all right, so that's important. So
that is if we're dealing with services. Okay, Now in your case,
if you're not dealing with services, then you're dealing with two fifty ninety six,
which is bonding other enclosures. Now you said that what you're dealing with
is not over two hundred and fifty volts to ground, So a one twenty
two forty volt is not over uh, two hundred fifty voltes to ground one
one twenty to ground. It's two forty phase to phase. So you're going
to be in if it's a feeder, then you're going to be in two
fifty ninety six. And what that states, it says the general says metal
race ways, and that's what you have, okay. Uh, cable trays,
cable armor, cable sheathing, enclosures, frames, fittings, and other
metal non current carrying parts that are to serve as equipment ground A conductor or
with or without the use of a wire type supplementary equipment. Ground conductor shall
be bonded if necessary to ensure electrical continuity and the capacity to conduct fault current
likely to be imposed on them. Okay, so at this point, locknuts
would typically be fine. Now, if that is a nipple that is rigid,
then you're gonna have a locknut on the inside and a locknut on the
outside. So you're gonna have mechanically right, but you're gonna have it done
that way. Uh, and that's how you're gonna basically installing. That makes
sense. Hopefully that makes sense in the application and any really at that end,
at that point you don't because you think about it. If you're if
you're throwing thread at the nipples, for example, it's a raceway, and
you only put the threading on the inside because there's no fitting, then it's
common sense you're gonna have to need a locknut on the outside as well.
Otherwise it's just no way it's gonna work. It should be common sense.
But anyway, but again, the lock nuts in this point can be fine.
Now, if you have any paint that needs to be removed so that
the or you have locknuts that dig down into the metal. Okay, you're
done, But that's a feeder. So that's the difference. So for you,
you're gonna be looking at two fifty that ninety two if it's a service
conductors in this raceway slash nipple, or if it's feeders, you're going to
be looking at two fifty ninety six for your application. So hopefully that answers
that question for you. That's about the best I can give you, because
again, your question kind of gives me the notion that we're talking services,
and then the next minute it's talking feeders, and you describe the circuit with
an equipment ground, so that sounds like a feeder. So I figured it's
best that I give you both. How about that. Okay, we got
another question here, and this is a long one, and I'm not going
to answer the entire question because it goes into a scenario on a job site,
and for liability reasons, I'm not going to get into your design and
what may or may not be happening here. I'm going to get into the
crux of your main question, and that should answer the other part of your
question. Again, this one's difficult because it does get into questions about designs.
So let me just answer this question here. It says, when would
I be required to treat a generator as a separately drive system or is it
always an option one hundred percent of the time at least as far as the
a NEEC is concerned. Okay, So a separately drive system, for if
you have a standalone generator, then it's always a separately drive system. If
it's a standalone generator. Now, if the generator is tied to the building,
for example, then it's all going to be whether or not the grounded
conductor is switched or not. If it's not switched, then it's not separately
drive. If the grounded conductor, which in most many cases is a neutral,
if that is switched in the transfer, then it's kind of totally isolated
except for grounding and bonding applications. Right, But as far as the ungrounded
conductors as well as the grounding there's actually a separation or a break between the
generator through that ats or transfers, then you're going to have a separately drived
system. Okay, And we have a definition and in the twenty twenty three
of a separately drive system. So that's a separately drive system. Now,
like with whether it's a big system or small system, if I have a
generator connected to a building in the transfer switch has a solid grounded point,
it's not being switched, then it is not a separately drive system. It's
another piece of equipment. It's just another for lack of a better explanation,
it's like another range, even though it's not a range. We know that,
but it's just another piece of equipment. Okay. And so obviously there's
rules for generators. We won't get into that in this episode, but that's
the key thing when you're talking about a generator. Is it standalone, then
it's got to be separately drived. If it's If it has a transfer switch
and it's switching the neutral, then it's a separately drive system. If it
is not switching the neutral, then it is not a separately drive system.
Does it makes sense? Okay? And of course, as far as the
code concern is, once you know whether or not to treat it as a
separate drive system or not, is going to end up answering a lot of
other questions that you may have. Whether or not ground a grinding electrode system
is required for it or if it's not whether or not you're putting ground rods
at a generator just because the manufacturer of the generator wants you to, or
if you're required to do it. All those type of things start to come
into play depending So hopefully that answers that part of the question. Again,
I'm sorry I can't get into the long answer because you went into a very
long email and it would get more into me giving you design advice, and
I can't do that for legal reasons. I can't give you design advice unless
I had you under any contractual agreement for my consulting services. I answer a
lot of things on Let's Ask Paul, but I try not to design things
for people. That's up to them to do that. Okay, all right,
folks, Well that's going to end it for today. That's quite a
bit over thirty minutes of Let's Ask Paul. I have a many many more
I have to get to and I will get to those. But I do
thank you all for listening. Again. You can submit your questions to me
by just going to Paul Abernathy dot com. You may or you may not
agree with my interpretation. That's again, that's the beautiful thing about the code.
So again, if you go on the Internet, you'll see that many
people have different opinions and interpretations of certain things about the National Let's Go Code.
It is what it is. I do my best to bring my years
of knowledge together to try to help answer those questions for you. It's a
free service sponsored by Wicks, So all you got to do is go to
Paul Abernathy dot com and I am more than happy to tackle the questions for
you. Until next time, folks, stay safe, God bless and hope
you have a wonderful holiday asball boot both Aspallo Nothing Mask Nothing