Speaker 2: What up, everybody?
Speaker 1: 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 or all things electrically related. Hell,
you can ask me about bidding, estimating, hr firing, hiring,
whatever you want. If it's in the electrical industry and
you have a question, feel free to go over to
Paul Abernathy dot com and submit your question. If it's selected,
it will be used in an upcoming podcast much like today.
But I will answer via email, And if I don't
answer you via email within a couple of weeks, make
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get a lot of these, so I do want to
make sure I answer all your questions. But before we
get started today, I want to tell you that today's
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out trade hall dot net. All right, So today's episode,
we're going to tackle a question. And this question can
be quite controversial.
Speaker 2: For some people, okay.
Speaker 1: So it's one of those things where you have to
take this question and understand the concept of where we're
coming from when it's being presented. And again, everybody's going
to have varying opinions on this, okay, So I'm just
telling you that right up front, right up front. I
just want to clear the air up front, right So now,
the remember when you do send me these questions over
at Paul Abernathy dot com, make sure that you let
me know the code cycle you're in. And that's the
more germane to the response, because I want to keep
it with the code cycle that you're working on and
you know, and that way I can make sure that
I'm answering it, you know, to to your expectation. But again,
remember these are my opinions. You may agree to disagree.
That's perfectly okay as well. Never said I was no
tre Damis or even Tesla Elon Musk. I never said
I was Nikola Tesla, you know, all that kind of
good stuff. I'm just me electrician like you who have
been doing this for over forty years, and I'm trying
to give my best to help you understand the National
Electrical Code and how things may apply. Okay, so this
question was submitted, and I'm going to read you the question,
and then I'll go back and I will pick through
the question and try to answer some of these things
that are involved in it.
Speaker 2: So I just want to make sure that I do
that on the front end. So let me read the
question first.
Speaker 1: It says, first point of disconnect is the main service panel. Traditionally,
for PVC conduits carrying the service conductors from the panel
to the meter pedestal, we ask for a green wire
for continuity between the two. The argument recently made is
that since the ground and the neutral or bonded at
the panel, that running a separate ground is now splitting
the neutral and creating an imbalance. Therefore, there should not
be the green wire. Is this correct? And how is
this different than using rigid pipe to bond it. Luckily,
we recently switched to the twenty twenties, so all pedestals
will have the first point of disconnect, I guess, and
we'll eliminate this issue. Thanks for all your help. Okay,
thanks for the question, and we'll basically let's dissect each
this down each one of these.
Speaker 2: Okay.
Speaker 1: The first statement is that the main service panel is
always the first point of disconnect, not always the case,
not always the case, because you could have a situation
where if you have one and two family dwelling, then
you've got an issue where you may have what's.
Speaker 2: Called an emergency disconnect out there.
Speaker 1: So that may be your first point of actual disconnect,
and it may or may not Okay, may or may
not be a service And we find that under two
thirty dot eighty five that's emergency disconnect one and two
family dwellings, So that's a disconnecting means, but it might
not be the first that might be the first point,
and it may or may not be service equipment. You
got to go read two thirty dot eighty two and
see that there's some options for this. When it comes
to the disconnect. You can have a service disconnect. It
could be a meter disconnect, or you could be some
other listed disconnect switch there. Uh, that doesn't change the
fact that there's still service conductors. It's just a disconnect
that type of thing. Now, if it is service conductors
and you have this disconnect, then everything on the load
side of that will be feeder applications. But again, go
look at two thirty dot eighty five now understanding emergency
disconnect applications. Okay, So going with the premise that that's
that we're talking about a service panel and he's talking
about between the meter and the service equipment, which again
we'll assume that it's outside because now you're required to
have an emergency disconnect, and so we'll assume that that
service disconnect is also the emergency disconnect. If they are
in the twenty twenty code, then that would be required.
Speaker 2: If they're in the.
Speaker 1: Twenty seventeen code, then the disconnect outside or nearest point
of entry, and there is no requirement for emergency disconnecting
the twenty seventeen NEC. So we'll assume that they're talking
about the twenty seventeen edition which did not have that
emergency disconnect requirement.
Speaker 2: Okay, Assuming all.
Speaker 1: That a lot of a lot of assumptions there that
I'm making on this episode.
Speaker 2: Okay, all right.
Speaker 1: Now, the other argument he's saying is their jurisdiction requires
them to run a green conductor for continuity between or
say a bonding jumper between the meter enclosure and the
service enclosure.
Speaker 2: Okay, and so.
Speaker 1: That's what we're keeping the context to their question, assuming
again twenty seventeen no emergency disconnect. So they get them
to do this, and the question is being brought up,
is that creating something like objectionable currents? Is that creating
an imbalance in the neutral conductor? And he answered to
that is one, yes, it is creating an imbalance because
current takes all available paths. It's not just the path
of least resistance. It takes all available paths. And we're
designing a system so that the current will travel back
on the neutral conductor. Okay, it's going to always carry
some amount of current, right, Not so for the metal parts,
even though they're connected together at each en You know,
you have the meter and then you have the neutral
that's connected in the meter typically, and then you have
the service panel and the neutral is connected based on
two fifty twenty four, it's connected in the service with
the main bonding jumper to the enclosure. Okay, so they're connected.
The neutral is connected at both ends. So but the
concept is you only want the return current back to
the source to be traveling on that neutral grounded conductor.
Speaker 2: Okay, that's what you want.
Speaker 1: And so in their situation, they are forcing people to
put a green wire in there and obviously connecting it
to the neutral at each end, which does create parallel paths,
which does mean that the you're going to have return
current imbalance. Now, many people may look at that and say, well,
if I'm have less current on the neutral, what's the problem. Well,
that's because that whire you're installing for the green wire
is a bonding component, it's part. It really wasn't designed
to carry the current, although now you're forcing it to
do that. Now it may be sized smaller than the
neutral that you have already sized. If that's the case,
if you lose your neutral, then your return current's going
to be back on that green conductor that may not
be sized properly.
Speaker 2: So that creates a problem.
Speaker 1: Now, if you have that green wire connected at each
end to the neutral conductor and y'all are demanding that
to take place, then what's happening is that you also
are creating objectionable currents because you do have circulating currents
that are traveling on the metal parts back to the source,
and not just through the grounded neutral conductor, but also
through obviously this green wire, and you have basically forced
them to construct a parallel path that can conceivably create
objectionable currents, and it also is forcing an unnatural balance
on the return current because it's going to take all
available paths to proportional to the impedance of the path
with the lowest impedance. Okay, Now, obviously the bigger neutral,
probably bigger than the green wire, is probably going to
have a bigger conductor because you're sizing the neutral based
on not smaller than two fifty one zero two c
one plus you're taking into account the calculated load that'd
be on that neutral, so maybe it is larger, and
so the larger it is, it's going to carry more current. Right, logically,
it's going to have lower resistance than the smaller green
wire until you lose that neutral, and now you've got
it traveling on the green wire, and that can create
a problem. Now, as far as the National Electrical Code
is concerned. We have to construct circuits in a way
that do not create objectstionable current. And then the code
in two fifty six tells us, you know, you got
to do something to mitigate this where possible. And so
the first thing that I would say to mitigate this
would be to remove that green wire.
Speaker 2: And remember that the National.
Speaker 1: Electrical Code permits the use of the neutral conductor on
the supply side to bond metal parts bond that meter enclosure.
And you're doing it in the panel by using the
main bonding jumper and connected the ground conductor to the enclosure.
So you're doing it at the panel, and you're doing
it at the meter. For the most part, in most
one and two family dwelling meters, the neutral conductor is
connected to the enclosure. You know, you can easily test
that out when you're doing an installation. Just use a
continuity tester and touch the neutral terminal and then go
over and touch the enclosure. Usually use one of the
threaded entries so you get rid of all of the
paint issue and you'll get you'll get a reading and
it should be connuity that tells you that the neutral
is inherently connected to the enclosure. If you're going to
be running that green way, if I are between the
two you, and if you're a jurisdiction, it's forcing that.
Then you're forcing a violation of two fifty dot six.
You're forcing a potential issue of neutral return current traveling
potentially on the green conductor, especially if there's a loose
connection in the ungrounded I mean, excuse me, a loose
connection in the grounded neutral conductor. So you're introducing or
you're you're making them do things that are that potentially
could cause issues. Now, the other thing that was asking
the question this says, well, wait a minute, wouldn't this
be the same if I had a meter and I
went back to back with a rigid metal conduit and
I'm connecting it to a panel enclosure. The short answer
is yes, you are still creating an issue that could
create objectionable current. Why because if the neutral grounded conductor
is connected to the enclosure at the meter, and you
know you're doing it per two fifty dot twenty four
at this service equipment, then you are inherently creating this
same concept. Now they're kind of asking, well, why do
they allow it for the rigid But we shouldn't allow
it with the green wire. Well, I think the issue
is that we known for eons that it's a problem
with using the rigid metal intermediate metal e MT between
the meter and the panel and then running a neutral
through that we and the way we bond at each end.
What happens is we're creating this this potential for an imbalance.
We're creating this potential for parallel paths. We're doing all
this and the code is kind of tells you not
to create objectionable currents, but it doesn't define what objectionable
current is. But we know that it's basically objectionable current
is current traveling on an unintended path. Right, it is
not designed to be traveling on the metal parts. But
when you connect it to the neutral grounded conductor in
the service, and you do it also at the meter,
you are creating this potential. Now, this has been done forever.
We tried to talk about this in code panel five.
We tried to come up with a.
Speaker 2: A objectionable current definition.
Speaker 1: We tried to do this, and people say, well, why
don't you just flat out just require non metallic type
of raceways between it and you solve that issue Okay,
well we could, but you got to remember the NEC
is not an instruction manual.
Speaker 2: It's just guiding you. And there's many options.
Speaker 1: For example, they do make transition fittings, whereas if I'm
using RIGID, I can transition between the rigid to PVC,
and I already know that the one end of the
rigid's bonded because it's connected to the metal box on
the panel side. But maybe it has a transition and
it changes over to PVC as a fitting or as
a coupling, and you get a transition fitting and change
is over, and so you break that connection. Well, then
you've broken that parallel path. You still bonded the metal
parts that enclosed service conductors. Okay, we're following all of
those rules and two fifty ninety two, but you're breaking
that bond and so you're you're separating it out. Also,
you could have a meter that gives you the ability
to not have the grounded nutril conductor connect to the
to the actual enclosure, and then you wouldn't have a
parallel path if you did run a green wire through
there and connect it to the enclosure. Okay, because that
neutral is isolated in the meter. That's options, but most
of the time traditional meters, that's not going to be
the case. The grounded nutral conductor is bonded to the
enclosure because allows the neutral to be used to bond
metal parts on the supply side of a service disconnect.
So you know, there's no fancy dancy way around it.
Do we see rigid used all the time on the
supply side? Is it potentially a violation of two fifty
out six?
Speaker 2: Sure? Do we see big problems with it? Not really there.
Speaker 1: Really, it's the touch potential thing that's that's helpful with
the allowance of two fifty one forty two and to
use the ground a conductor at that application. But we're
talking about different things when we're talking about return paths
or creating parallel paths that uh that cause current to
travel on things that it wasn't intended for it to be.
There's a lot more impedance on a metal enclosure and
things like that than it would be on a direct
conductor connecting from point A to point B. So current
is going to take the path of all all possible paths,
but proportionately it's going to take the path of least impedance. Proportionally,
so the large majority of the amount of return current
is going to travel on its intended path, and so
we try to construct things that way. Just because you
see people using rigid on the supply side and have
a neutral inside of that raceway and the raceway and
the neutral bonded at each end, yes, they're technically creating
a violation, but it's.
Speaker 2: Become an accepted practice now.
Speaker 1: When you force somebody to put a wire in a
raceway to create that problem, that's different because the ahjs
or municipalities should not be forcing these things on people.
Because the only way that we can remove the two
fifty six issue in this case is to remove that
green wire, but then we have to ensure that are
if we do that and you're using PVC, for example,
between the two, then we have to make sure that
the meter enclosure is connected to the ground of neutral,
and that may be again already inherent in the meter.
But then obviously we're doing it on our service equipment.
We're making sure we put that main bonding jumper in
there and everything gets bonded together there that type of thing.
So I don't know if that answers your question that
you presented but again it kind of gives you things
to think about. Just because you see somebody using rigid,
does that make that right? It's just you know it,
just people do it. But for a jurisdiction to force
somebody to put a green wire in there and create
parallel paths, to me, is a little more intrusive than
them constructing a rigid or intermediate or an EMT to
protect the conductors on the supply side and inadvertently creating
a potential of a two fifty six issue than it
is to force somebody to put a wire in there
and intentionally create this issue that type of scenario, right,
And we've also heard stories that raceways, for example, when
we're doing like equipment grounding conductors. There were study, the
Gemini study that was done and I'm I'm a conductor guy,
don't get me wrong, but you notice that when it
comes to raceways, we don't tell you how to size
a raceway to clear an overcurrent device. If you're thinking
about an equipment ground we tell you how to size
a conductor. We send you to two fifty one twenty two,
and you size it based on the overcurrent device. We
give you that, but we don't give you instructions for
the raceway. In other words, we don't tell you that
a trade size half or three quarter or one or
one in a quarter or one and a half is
going to carry a certain amount of current that's going
to clear it over current device. We just assume that
it's going to and so we don't really get into
sizing there. So that's why some engineers that are in
a pinch, you know, they didn't size it right, the
raceway right, and they got conductor fill issues. Well, they
can remove the wire type equipment ground that they insisted
on installing and use the metal raceway. If it qualifies
in two fifty one eighteen, then they can use it,
and that way they can you know, get away with
the raceway fill issue they may have introduced. So there's
many ways to get around certain things, all compliant. The
only downside to using a raceway as an equipment ground
for example, and I know I'm.
Speaker 2: Deviating from our original topic, but the.
Speaker 1: Only thing to ensure is that all the connections are
made uptight, that you don't have any weakness in this
raceway system, because obviously the raceway system is only as
good as every termination, every coupling, every connector, and so
again you have to do a little more due diligence
to make sure that works, whereas a wire is pretty
straightforward point A, point B, terminate and done. That's why
more engineers just require an equipment ground or the wire
type in a raceway than to use the raceway. I
get it, but again as a little off topic, because
we're talking about on the supply side where you're not
going to have an equipment ground because there's no overcurrent
production device of Barry. Get what I'm saying. All right, Anyway,
hopefully I answered your question. I know you probably wanted
me to give you definitive but again that's just how
the code works, and that's how it is, and there
are certain practices that we do. And again there was
a reason the Code Panel five could not come up
with objectionable current definition because we know that in certain
cases we're imposing something that would be contradictory to what
we're trying to achieve. And so basically the concept of
objectionable current is we don't want current travel on unintended paths.
But we understand that there are certain applications in any
c that may introduce that. So we don't want to
put something in writing that we can't truly be able
to hang our hat on it as a definition, so
we leave it pretty open. And so that's how you
get my interpretation, that's how you get other people's interpretation
of this that type of thing. But that's the best
I got for you, all right, all right, hopefully you
got something out of that and something to take away
from you. Again, make sure if you have any questions
that you want to submit to us, just go to
Paul Labernathy dot com. We love to have you and
we'll catch you on an upcoming episode of Let's Ask Paul.
Till next time, Stay safe, God bless basket co don'hing