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so today I have it. Let's ask Paul and I will say we are
also were streaming live on TikTok, not answering questions on TikTok, but we
are streaming live on TikTok, and we want to make sure that I answered
this question accurate because this could be a long one today, and I'm sure
that TikTok folks won't hang in there that long. Okay, that's a three
minute platform. Tension spans probably less. But I have a question. It
was submitted to me, and this question was, Paul, can you teach
me a little bit more about MC cable? It's uses, it's not permitted
uses. What's the difference in the types of MC cables and some examples where
you can and can't use MC? Metal clad cable? Okay, So one
of the more popular wiring methods out there, probably for residential, the most
popular is no metallic sheeth cable. The second most popular, probably residentially and
like commercial, is going to be metal clad cable. Now, three time
types of MC cables that are available in the industry. Okay. The most
predominant is called an interlock. Now. Interlock type of MC is made by
taking a perplexed set of conductors, running it through a machine that creates what's
called we call it a bird beak, but actually it wraps a continuous reel
of metal armor. It wraps it around that cable assembly, and then as
it's wrapping it around, it has a little beak that bends it and turns
it, and it actually kind of creates the spiral and it interlocks it.
That's why it's called interlocked, okay, so it shouldn't be able to pull
apart. And of course the other type is smooth and corrugated. Now,
smooth it kind of sounds just like it is. It is a constant extrusion,
and it's extruded out just like you would like an EMT would be.
And then there's the corrugated, and typically corrugated is welded. Okay, it's
essentially like an interlocked, but it has a welding component that welds the different
convolutions together. Still as flexibility obviously not as flexible as interlock, but it
there are some benefits to smooth and corrugated. Smooth and corrugated, you can
actually use the armor as an equipment ground in place of having to have one
inside of the cable assembly, whereas interlocked that's not going to work. Now,
there are specialty products like Southwire has a product called mcap Uncoal wire as
a product called smart ground, and you can use the armor as an equipment
ground and those specialty products, but only up to conductor size. Is a
six gage. Okay, so anything larger than that. Obviously, with interlocked
ms that you can't use the armor and you still have to bond it,
but you can't use it as an equipment ground. Okay, that's not the
case with corrugated and smooth. Now corgating smooth type of MC cable, I
can use that armor as an equipment ground. Okay, So it eliminates the
need for a separate equipment ground and conductor inside the cable assembly. All right,
but that's just a kind of a quick overview of that. Let's get
a little bit more deeper into talking about MC cable and trying to answer this
gentleman's question here. And remember, if you have questions, you can always
submit your questions to me at Paul Abernathy dot com. Please make sure you
do that. All right, we're talking about metal claud cable. There's multiple
types of metal clad cable. They all have to be listed. Dot six
of Article three thirty requires that they all be listed. Now most I would
say, all of the wiring methods are are required to be listed now.
Dot six is the listing requirement. And if you're following along, I'm in
the twenty twenty three edition of the National Electrical Code. Right, so I
have transitioned. Whether you have or not, whether you're stays using Again,
it's usually irrelevant to me. Because I'm an educator, I always go with
the latest addition. I do ask people to when they ask me a question,
I like them to ask me a question and let me know what code
cycle they're in, because again I can be more relevant to the cycle there
is. Otherwise I'm going to give you an answer that's in the twenty twenty
three. That's just the way it works, all right. Now, let's
talk about some uses permitted for mc cable. A lot of misconceptions about the
application and use. MC cable is perfectly permitted to use for services, feeders
and brand circuits applications, whether it's small conductor size, long feeder, mid
sizes with four outs two fifty three, fifties, four hundred case email,
perfectly fine. But again use for service feeders and brand circuits. Again,
also utilize for both power and lighting, even control and signal applications. Most
people know that there's products on the market that have this zero to ten vault
control and signal inside of the same cable assembly as the power conductors that is
permitted in the National Electrical Code, but that's also my patents. I have
about four patents on that, and again we don't aggressively fight the patent.
I really don't care if other manufacturers make it. I don't make anything from
these patents, but I am the patent holder of that. Anytime you grab
that MC cable and you have those zero to ten vaults in there, I
am My name is attached to that patent. Yeah, I don't make a
diamond on that. Because when you work for a manufacturer, you know,
they get all the rewards. I like to say, I got a job
so that you know takes care of that. Now, MC cable. When
you're looking at three thirty ten, people get kind of confused when it talks
about the general use because it says indoors or outdoor use. You know,
that's item number three. What they don't understand is indoor means just flat out
you can use the MC indoor outdoors. If it's a wet or damp location,
then you have to do something extra. It has to be some type
of impervious jacket that is corrosive resistant, that's extruded over top of the armor.
Itself. Okay, So when we think about that, you know,
we make MC cable people. You know, you can buy MC cable interlocked.
We'll keep the topic get interlocked because that's the most commonly used MC cable
today. It's available both p PVC jacketed as well as without PBC jacket It's
the exact same cable that's used in a wet location that has PV extruded on
it. It's an exact same product. It just takes it and runs the
whole cable through an extrusion, and it extrudes a certain thickness of PVC material
over top of the armor, and then we print the information on top of
that material. That's the only difference. Okay, But you cannot use mccable
in a wet or even a damp location. It is a dry location product
only. Okay. Now, Item number four says, and we're in three
thirty dot ten. By the way, Item number four says that it can
be exposed or concealed absolutely, So I can run it on the surface of
a building. If it's outside, it's got to be PBC jacketed obviously.
If it's inside, I can run it on the surface. We have to
be careful because if you run it somewhere that is subject to physical damage and
that may or may not be very obvious, that's going to be an HJ
call. Then it is not designed. Even though it goes through a crushing
impact with this quite impressive Okay, a thousand pounds or two thousand pounds,
depending on the size of the conductors. That's a product standard okay UL fifteen
sixty nine. That has nothing to do with the application in the field.
If somebody says it's subject to physical damage, then mc cable couldn't be run
there. But generally it's okay to be exposed or concealed. So if you
want to install it in the wall, no big deal. If you want
to install it on the wall, as long as it's not subject physical damage,
no big deal. You can do it, secure it and support it
properly and no problem. I am number five. People say it's is it
direct burial? It is when it's identified for such use, and that obviously
will be when it is PVC jacketed. It is obviously going to be identified
for that use. It's going to say right on the side of the jacket,
it'll say dB or a direct burial use. Next one people ask about
it. Number six cable tray were identified for such use. Absolutely, MC
cable king go on a cable tray as long it's it's part of its listings
for us in cable trays, the manufacturers will designate that on the actual labels
that they would put on the reel. The next one is in any race.
Another misconception. People say, you can't run MC cable in a raceway.
Well, most certainly you can, especially if it's a location where you
think it's going to be subject to physical damage, then you can most certainly
run it in a raceway. Okay, but nothing prohibits it from running to
a raceway. The only problem you have with MC cable is the requirements to
bond that as it comes to an enclosure. So I tell people all the
time and the requirements at through twelve dot five C. If you're talking about
enclosures, for example, I'll tell people it'll make sure you just stop the
raceway short so they can come out and then actually use a connector and connect
to the enclosure. That type of thing. Now, we have different allowances
in three fourteen for boxes, but at the end of the day, you
have to bond the armor. So if it runs into a box and it
doesn't connect to the box, how are you bonding the armor. So there's
some things you can do for that. But the key takeaway here is it
can it be in a raceway, aolutely commuter raceway. The next one is
aerial cables on a messenger. A lot of people don't realize that MC cable
can be run on a messenger messenger being from point A to point B,
maybe using a steel supporting component with a webbing from a building to a building.
So you know, keep that mind. Now, Typically if it's an
aerial cable, it's going to be designated. Is that by the manufacturer?
Not always, but there are many manufacturers. For example, there's a manufacturer
down in Houston, I believe it's service Wire who specifically makes a cable that
they call an aerial cable. Okay, the next one is number nine.
How's it just classified locations we're specifically permitted by other articles in this code.
Obviously that'd be five hundred five two five o three things like that. That's
where you get into the necessary needs for things like smooth and corrugated. If
you're going to have like an MC that's rated for a hazardous location and all
that type of things. So remember when you see a US is permitted in
three thirty dot ten, it is not germane just to interlock. This is
this is covering all the MC types, okay, and so keep keep that
in mine. Next one is number ten. It says in dry locations and
embedded in plaster finish on brick or other masonry, except in damp or wet
location. So it is permitted to be embedded in plaster on brick or other
masonry, except where there's a situation where the wall makes be exposed to moisture,
dampness, wetness, maybe an exterior wall or something like that, then
you can't do it. But if it's a dry location inside of a building
and they groove it out in the plaster, let's say, and they want
to embed it, that's that's not a problem. If the location is going
to be a dry location, okay, not going to be okay, if
the location to which that wall which is being betted embedding the MC into the
plaster, let's say, The problem would be if that is a damp or
wet location in general, and you just have to look at the location to
determine make a distinction whether it's a dry inside of a building unless you're in
a spray booth or in somewhere where they're going to host things down. Typically
inside the building in a conditioned space is going to be a dry location.
So this gives you that permission. Now, Item number eleven three thirty dot
ten has a change that I submitted in the twenty twenty three is to add
the word damp in there, because prior to the twenty twenty three it's said
in wet locations and it didn't make any reference to damp, although the standard
itself you Will fifteen sixty nine also really didn't address damp locations. So in
the twenty twenty three edition of the NEC, damp was added to item number
eleven thirty ten A just making it very clear that damp or wet locations where
corrosive resistant jacket is provided over the metallic sheathing and any of the following conditions
are met. So this is where we say, yes, I can use
MC in a damp or a wet location as long as I meet any of
the following conditions. Condition A is the metallic covering is impervious to moisture.
Well, that would be as smooth. For example, MC would be impervious
to moisture. Be says a jacket resistant to moisture is provided under the metal
covering, all right, So that is typically not what most manufacturer are going
to do. They leave the armor outside and put some kind of covering underneath.
The third one, which is C is the insulated conductors under the metallic
covering are listed for use in wet location. Now ours most manufacturers are going
to put thh in th th thhw DASH two And of course the thhw dh
two is perfectly okay for a wet location, so it's typically going to be
adequate for that. Now that can be typically misleading for a lot of people
because they go, okay, well, then that means I don't have to
have anything over the metal. Well you're gonna see in the three thirty twelves
and then we'll move pretty rapidly from there trying to explain the little nuances.
But I wanted to show you permitted uses and not permit uses as a key
component to you to your question that you submitted, because here's where we get
a lot of questions from people. And so again all of the manufacturers will
use conductors that are insulated under the metal covering that are actually listed for use
in wet location. They'll have a W signified in its nomenclature. Item number
twelve says, we're a single conductor KERS use and this is again an MC
cable where you have one single conductor running in it, all phase conductors,
and we're used the ground of conductors should be grouped together to minimize inductive voltage
on the sheathing. Absolutely, so in a rare case, we have really
large MC that has a single conductor in each MC. It's kind of like
m I cable, and when you run it, you want to make sure
that they're grouped in close proximity because you don't want any induced voltage on it,
and of course that creates inductive heating and things like that, and that
can cause all kinds of problems. So it's just a routing thing. But
they do make single conductor cables for applications where you might have rather large conductors
and you're running multiple phases each in an individual single conductor MC format. It
is available all right, specific uses. This is still under uses permitted,
but this is specific uses. It says MC cable show be permitted to be
installed in compliance with parts two and three of Articles seven twenty five. So
seven twenty five is dealing with signaling and control that type of applications seven seventy.
I believe it's fiber optic applications where MC is very prominent to have some
MC and also have the potential have fiber optic in the same assembly. And
so you have number one cable trays, says type MC cable installed in a
cable trays shall comply with and it proceeds to give you a bunch of three
ninety twos. Well, three ninety two is four cable trays. So it
has its different rules that you have to follow, how it lays in there
with the ampacities, how it's going to be adjusted. So again, the
great thing about the NC is while it's not an installation manual by any means,
it is a good minimum standard that lets you know, okay if you
want to put it in a cable tray. Here's some other code sections that
you must follow. Right next one is B two, which is direct burial.
Direct burial cable should comply with three UNDERD dot five that stepth of cover
and that's thousand volts are less than of course three oh five dot fifteen is
over a thousand volts, so you've got some appropriate applicable rules there. Next,
installed as service entrance cable, we said earlier it could be service cable,
So it proceeds to tell us that the MC cable installed as service entrance
cable shall be permitted in accordance with two thirty dot forty three. Course two
thirty dot forty three is a list of the different types of wiring methods and
whatnot that can be used as service entrance cable. And then either number four
is as installed outside of buildings are structured or as aerial cable, and it
proceeds to tell us that the MC cable installed outdoors of a building are structure
or as aerial cable shall comply with two twenty five dot ten. Course two
twenty five is outside branch and feeders, uh three ninety six is messenger,
and it tells us that you need to follow dot ten and dot twelve.
Those are going to be uses and use is not permitted as well under messenger
and three ninety six, So pretty straightforward if you're doing any of those types
of installations it's going to direct you directly where you need to be, so
you shouldn't have any concern all that. Now, let's talk a little bit
about use is not permitted where you can't use MC cable. Now, you're
gonna know that this is a very small list. It's it's only got two
items, so you know, typically from my experience, I have seen installations
where And also I should have mentioned that MC cable is available in both steel
or aluminum armor, and believe it or not, it's also available in a
copper armor. Rare for manufacturers to produce the copper. That's a specialty product.
A lot of times us with the variable frequency drive applications again, things
like that, but the most commonly used today is probably going to be the
aluminum. And here's an interesting fact. Aluminum or steal armor both at the
past the same crushing impact. I mean, the misconception that many people might
have is that, well, steel has to it's got to be stronger than
the armor, so therefore the test ratings would be different, and that's that's
not the case. So UL fifteen sixty nine and then subsequently UL twenty five
fifty six, all of the rules for MC crushing impact are exactly the same
whether it's steel or aluminum armors. So if you're buying aluminum or you're buying
steel because you think it's subject to physical damage that it can handle it better,
they both should be adequate, right. But they're not listed to protect
for physical damage. So that's the important key. If it gets damaged,
it needs to be replaced. Okay, So here looking at the use is
not permitted. If you have your Code Book three three thirty twelve, use
is not permitted Type MC cable shall not be used under either of the following
conditions. The very first one in the list is where subjects of physical damage
and we kind of talked about that earlier. Now, some of the questions
that people submit to me being on a code panel, being on a servile
code panel five and and code panel seventeen, and you know, one of
the things that people will ask is like, well, is there a definition
of physical damage? And it was attempted and people have submitted it through the
years. It has not been successful. It is it is never made it
into the code. And of course then we have terminologies like severe physical damage
and that also has not made it into the NC. So What has normally
been is that they believe that that is something that the ah J, the
authority having jurisdiction, the electrical inspector who's acting as the deputy for the building
official, or the building commissioner who is the actual age J, they have
to make a decision whether something is subject to physical damage. Now, my
hope is that we use a little common sense and realize that it might be
running along the wall, but unless somebody went at it with a hatchet,
it's not really subject to physical damage. Whereas if you install in an ERIC
where they do a lot of forklifts, a lot of things like that,
and you're running it exposed and obviously somebody could bang into it and it would
be subject to physical damage. Again, while everybody would like a uniformity to
this and a definition of this, the problem is anytime you start defining something,
then it locks it in and then people start arguing about the interpretation.
So we'll leave this one to the HJ and you the electrician, and y'all
can work that out. Okay, people don't like that. Again, the
moment that we start getting too defined in ANEC than people bitch and wine in
a moment where too loosey goosey with the NEC people bitch and wine. So
at the end of the day, you're not going to stop people from bitching
and whining. So at the end of the day, physical damage is going
to be up to you in the HJ to make that determination, and hopefully
the little common sense will come into play. Now, idem number two kind
of goes hand in hand with what we saw earlier when it said that the
conductor's inside as long as they're weighted rated for a wet location and that type
of thing, that be okay, right, Well, here you go.
It says, now we're exposed to any of the destructive corrosive conditions in A
or B unless the metallic sheathing or armor is resistant to the conditions or is
protected by material resistance to the condition. So this is that extruded jacketing,
Okay, extruded all over it in jacketing. And so there's an A and
a B. Here A says direct buried in the earth or embedded in concrete
unless identified for direct burial. Now, most manufacturers that produce MC cable,
okay, are going to produce the MC cable and on the outside of it,
it's going to have the extruded PVC material typically black. Nothing says it
has to be black, but typically extruded black because that's the most that's the
most purchased pelletized materials. So you buy that in bulk. So colors cost
you cost money. Uh, not that black is cheap, it's just that
it's it's the most predominantly base used, so that's what everybody uses. That
doesn't mean you can't order it in color, so you probably can. You're
just gonna have to buy a crap load of it in order to be able
to do that. But on the outside of it, it's going to be
printed with direct burial and that's what it's going to give you the permission to
embed that into the earth or to actually embedded in concrete. Now b is
exposed to cinder fills, strong chlorides, caustic alkalies, or vapors of chlorine
or of hydrochloric acids. Okay, So this is why I tell people in
that in UH six eighty when it comes to swimming pool applications, they want
to know when it talks about corrosive environments six eight fourteen and all this other
stuff, can you use PVC jacketed MC. And my answer to that is
absolutely you can. And people want to say, but it says such as
this, this, this, this, and this, and doesn't say MC.
But at the very first line it says, we're listed for the for
the use. Well, we're talking about a corrosive environment. You're never going
to have a manufacturer list that for swimming pools, even though that is an
option. Nobody's going to do it. But it is listed for corrosive environments.
It's in the earth. It's just like it says right here. So
at the end of the day, and PBC is very resistant to these type
of things, so it most certainly can be used in that application and it
is very resistant to the corrosive effects. So I'm a believer that that six
eighty dot fourteen absolutely would allow me to use a PBC jacketed MC and those
applications for pool installations. Okay, you know, and I don't really give
a damn what anybody says. It's I know because I helped submit that rule.
So anyway, enough of that, All right, what about exposed work
again? So if you are going to install MC, cable and disposed worth,
then you've got three three thirty fifteen that is titled exposed work right pretty
straightforward. It says exposed runs of cable except as provided in three hundred eleven
B, which sounds like it's going to be supportive above submitted ceilings and things
like that. It says shall closely follow the surface of the building finish or
on running boards. So you don't want you want to make sure that if
you're going to on this MC, you're gonna run it along the surface of
the building. If not, it's gonna dangle from joist to joyce or whatnot
like that, then you want to have it on running boards. It says
exposed runs shall also be permitted to be installed on the under side of joist.
We're supported at each joyce located so is not to be subject to physical
damage. You know, with non metallic sheet cable, you can run it
on the joyce, for example in crass bases, but it has to be
equivalent to eight three or six two and then you can support it underneath.
Other than that you gotta go through board holes or running boards. While here
it doesn't say anything about that, but the difference here is that if you
do want to run it exposed let's say on the under side of Joyce,
then you're gonna have to secure it at every single joist. Okay, yep.
So ironically enough, if you run it, if you just put up
a running board, then you can just secure it at its securing requirements of
three thirty dot thirty and every six feet and then you don't have to have
it every choice. Because you're running it on a running board, it's totally
up to you. Or you could bore holes and run it through the board
holes and you have to worry about it. Let's see here three thirty dot
seventeen through or parallel to framing members. It says type MC cables shall be
protected in accordance with three hundred dot fo AC and D we're installed through or
parallel to framing members. Right, so when people talk about that, you
have to remember that three three hundred dot four I don't know if I said
three thirty three hundred dot four A talks about through wood members. Okay,
so if you're actually installing through wood members, then you're going to have to
worry about things like nail plates. Okay, the exception doesn't list MC cable.
By the way, you know, notches in wood, same same applications,
So just be careful with your your installation. Remember you're gonna have to
still comply with three hundred for AC and D. If you're running through framing
members or parallel to framing members, you still have to have those rules.
And typically what we're talking about as an inch and a quarter separation, that
type of thing. Let's see talk about radio the bending radius, because again
people that run mc cable are bending it all the time and they're wondering,
Okay, what's the what's the tw tight Can I bend this stuff? Well,
obviously if the backside of it busts out the convolution, then you do.
You don't screwed up. Uh. There is no known listed way to
repair mc cable that has blown a convolution, right, The only known thing
to do is repair it. Not mean not repair it, I mean replace
it. There is no repair. Now. What you want to do on
your own, how you want to do it on your that's up to you.
You're the electrician, you're the one installing it. Whatever you can get
past inspector that, that's on you, right. But reality is, there
is no market available repair for mccable. The convolutions have pulled apart, so
you have to replace it, and you can put junction boxes and make us
splice skin those boxes. The splices have to be accessible and all this kind
of stuff. But at the end of the day, you know you you
you've got to try to install it without damaging that convolution. Now, one
of the ways that you can damage convolutions is the bending radius. Now interesting
at three thirty dot twenty four, which again DOT twenty four is consistent with
most of the wiring cable articles when it comes to bending radius. In m
IS dot twenty four trade cable everything is dot twenty four when it comes to
bending radius. Ironically, a little tit bit of knowledge. There's nothing in
the National Electrical Code about bending radius when it comes to six hundred volt conductors
or a thousand or less. To be honest with you, you're going to
have to seek the manufacturer's guidance when it comes to single insulated conductors on what
you can bend in what you can't, and most manufacturers will give you some
guidelines. They're only recommendations with their guidelines. Now, when you're over a
thousand volts, then the NEC does give you some bending radius rules. Maintained
bending radius rules for conductors, right, but really not for a thousand volts
or less. So you just be careful. If you've been a conductor too
tight, then you'll notice on the backside, if it's color conductor, it'll
start to opaque. And that is the elongating out the insulating material, which
is weakening and thinning. That insulated material kind of defeats the purpose of it.
On the inside of it, it creates what's called a calipillar, and
that caterpillar could split right down the middle now, exposing the copper core,
and that's a problem as well. The whole purpose of the insulation is to
help with the heat as the conductors are currents passing through the actual conduct so
and of course it also keeps it from touching components that are not to be
in contact with conductive surfaces, which can create a hazard. So you want
to protect the insulation. Now when it comes to a cable, bending it
too tight can damage it not only the inner but the outer and cause the
convolutions to pop loose. And that's that's going to be a problem. Now
you'll look and see that at three thirty twenty four, I told you earlier
that there is smooth sheathing, and then there's interlocked, and of course there's
a corrugated sheathing. Again, just to rehash it, smooth sheathing is is
like a continuous extrusion kind of looks like if you've never seen it, kind
of maybe a little like an m I. But it is does have convolutions
and how it's extruded, and I've seen that mostly smooth I see in copper
extrusion for a sheathing, But smooth is smooth, just like it sounds.
Interlocked armor is what most manufacturers make. It's again continuous strip of metal that's
actually aluminum or steel. It's actually been around the conductors, and then it
has a little beak at the end that kind of creates a little interlock to
hold those convolutions together. And then of course corrugated is a corrugated still in
the same nature of an interlock, but each each convolution is well and sometimes
excuse me, sometimes referred to as CCW. Now, the bending radius is
for smooth can be ten times, twelve times, or even fifteen times,
based on the diameter of the actual metallic sheathing. Obviously the bigger then you
know it wants to keep fifteen times it wants to. You know, you
don't want to bend that too tight. It's very easy to damage the sheathing
on that. Interlocked it's seven times the external diameter. That's also the same
for corrugated. So all you do is go to the manufacturers product sheets.
They're on everybody's website, find out what the exterior od diameter is of their
armor. Multiply that by seven, and that's going to tell you that your
bend cannot be greater than that. It has to be at least that radius.
Okay. So thinking of a radius, we're thinking of a ball.
The radius is from the center out, okay, circumferences around radius is from
center out, So you're bending it around that radius. Okay. It's like
bending it around a softball or baseball, if you will. And then of
course you have diameter, which is all the way across, okay, So
the different dimensions that you're dealing with. But we're talking radius, okay,
and so it's it can't be more than seven times the external diameter, okay.
And it says right up in the beginning of three thirty twenty four it
says bins of mc cables shall be so made that the cable will not be
damaged. Okay, so that's the first part. If it's obvious damage to
it, that's a problem. In your HJ is going to call out three
thirty dot twenty four. Now it says the radius of the curve on the
inter Okay, the inner part that is to not be less than required in
three thirty twenty four eight through c in course smooth could be ten, twelve
or fifteen times, but interlocked or the core gated, it's going to be
seven times. Now if you have shielded conductors, so we have an MC
cable within it's shielded conductors, then it's twelve times the overall diameter of one
of the individual conductors or seven times the overall diameter. So again, depending
on the size you have, you may be using the individual conductor or you
might be able to using the overall diameter of the multi conductor cable. The
fact is you're going to use the value twelve times whichever is greater. So
if the value ends up being greater measuring for the individual conductor than it is
for the overall diameter of the multi conductor cable, then you're going to use
whichever is greater In most cases, if you have shielded MC, that's where
you have the MC and inside that you have a usually what is a polyfoil
shield. Chances are you going to use the diameter of the whole assembly,
right, You're going to use the overall diameter of the multi conductor cable rather
than any individual conductor. So then it's gonna be just seven times just like
you would with interlocked and that's going to be maintained. When it comes to
securing and supporting three thirty thirty, we have a general we have secured and
we have supporting when we have unsupported cable. Now, the general rule is
MC cable should be supported and secured by Staples. Yep, it's just regular
Staples cable ties listed and identified for securement and supporting. You know, I
don't know why the hell you would have a cable tie if it wasn't for
securing and supporting. I mean, that's the whole damn purpose of a cable
tie. So I assume that most of the cable ties you buy, especially
if you're buying it from supply house, which are probably way overpriced, then
they're going to be okay, and they're going to be listed for securing its
supporting. It also says straps, hangers or similar fittings. What's a similar
fitting something that is similar to one of these that we just mentioned, same
kind of function, same intent. But it also goes on to say or
other approved means designed and installed, so it is not the damage the cables.
So this allows for introduction of other products, other different things that have
come out on the market. And as long as you can present to the
HJ something from the manufacturer, they are the ones that approve it okay.
So if they're okay with it, then okay, you can use it.
There's companies racketeer different things like that that make other products that are similar to
maybe the hangers and straps, whatever their own flavor on it things, and
they're utilizing these allowances and the approval means. Again, if they designed it,
they market it, and you follow the instructions and it's not going to
damage the cable. I don't have any problem with it. Again, it's
all about supporting and securing him, and that's the key. One thing it
was added for clarity in the twenty twenty three edition of the National Electrical Code
was that MC cable fittings that's the connector at the end shall be permitted as
a meat as a cable support. So if you're going from a box down
to a luminaire and you have let's say allows you to go six feet,
let's just say then from the last support it allows you to go six feet,
Well, that cable fitting is considered as far as it code's concerned,
a support. So if you're going up to six feet for example of let's
say unsupported cable, then it's supported at the box because of that fitting.
And that was actually added for clarity in the twenty twenty three edition of the
National Electrical Code. Okay, now let's talk a little bit about securing and
supporting of MC cable Securing unless otherwise permitted in this code, cable shall be
secured at intervals not exceeding six feet. Okay, So that's your general So
you're going to be securing it at intervals of every six feet along its run.
Okay. Now, interesting it says cables containing four or fewer check us
out. A lot of people don't know this. Cables that are four or
fewer conductors size no larger than ten Okay, So if they're not longer,
not they're not bigger than ten. So you have a you know ten,
three, ten, four, yeah, ten, two, twelve, three,
twelve two, all those under ten, okay, and it's got to
have four or fewer conducts, right, shall be secured within twelve inches of
every box, cabinet fitting, or other cable termination. So wherever you terminate
that cable, okay, So you're gonna have to have a you know,
you're gonna be securing it within twelve inches. Now, it says in vertical
installations listed cables with ungrounded conductors of two fifty kcy mill and larger shall be
permitted to be secured at infos not exceeding ten feet. So this is vertical
running up because typically between floors it's ten foot spanning and as long as it's
two fifty kcmil. Now that's kind of ironic to most people because the bigger
the cables, the more the weight you're running it vertical, you have a
bigger, great, bigger risk of slippage of those conductors. But remember,
securing the cable really is irrelevant to the conductors inside of it. So unless
you have a product that's designed for those conductors not to slip, and normal
MC cable has to go through a pullout test, so it shouldn't slip if
the convolutions are compressed onto the conductors like they're supposed to be. Sometimes it
can get a little loosey goosey, but it's supposed to be in a situation
where the normal changes of direction in the run of an MC is going to
add enough frictions so those conductors do not slip. If you're running a pure
vertical run from a box to a box and it's extended run, say one
hundred and fifty feet, then be careful. You have to use a product
that will secure those conductors inside or put some offsets in it in order to
keep from slippage taking place. Sometimes that's easier said than done. But people
like to refer back to the rules in three hundred nineteen. I think for
supporting conductors that only applies to race ways. That doesn't apply to cables.
So again we might tell you to follow that and where to put your off
sets, but that's not even really applicable to the MC cable, to be
honest with you, let's see. Oh, the other thing that people ask
me with this question is and the obvious is okay, Well, I understand
if it's cables containing four or fewer conductors and they're not larger than ten,
that they have to be secured within twelve inches. Well what if it's more
What if it's larger than that, or it's a ten with more than four,
then you can go all the way up to six feet. You don't
have to do it within twelve inches. Okay, makes sense because the general
rule is to secure at every six feet. Okay, this is only talking
about securing a cable within twelve inches of a box. Win it's four or
fewer conductors and they're no larger than ten, awg, Okay, that's when
you have to do it within twelve inches. So quite interesting that people don't
know that when they're doing feeder applications and they're running MC cable and they are
told to secure that within twelve inches and they not necessarily have to, although
it, you know, probably easier to get all your folks on the same
page. Anyway, you're gonna do it within twelve inches, but most people
don't know that you could go up to six feet on that. So if
an inspector fails you because you're not secured within twelve inches, and it's a
larger MC than you're like, dude, I can go up to six feet.
These aren't four or fewer conductors sized ten and less. So just just
so you know, still gotta put a strap in your ownwhere and so,
hey, you want to stop an argument, put it at twelve inches and
nobody's going to argue. But I just want you to know the rules there.
Now, what about that was securing. Now, let's talk about supporting.
Now. It says unless otherwise permitted in this code, and it will
give you when it says unless otherwise permitted, you're gonna see in a second,
we have what's called unsupported cables. So that's a that's an area where
it's otherwise permitted. It's it's given you some allowances to have unsupported cable.
So, but the general rules are what we're talking about when it comes to
supporting, unless otherwise forbidden in this code, cable shall be supported at intervals
not exceeding six feet, so every six feet, okay. It also goes
on to say horizontal runs of MC cable like running through framing members, things
like that, running it through joys, things like that. It says installed
in wood or metal framing members, or similar supporting means, like maybe across
the let's say, webbing of the ceiling, webbing joists, or whatnot.
It says that running across that shall be considered supported and secured means you don't
have to do any it's if you're running it through board holes or you're running
through metal framing members, it's considered supported and while it's not physically secured,
it's not going anywhere. So it's considered to be secured as well, as
long as he supports don't exceed six feet. So if they're if they're eighteen
inches on center, no big deal. Twenty four inches on center, no
big deal. But if you have running through framing members or running through joists
and the ceiling or the eye beams metal beams, and you have a span
that's more than sea six feet, then you have a problem, right,
But if the spans aren't more than six feet, then they're considered secured and
supported. You don't have to do anything different to that. Let's see now,
let's go, let's see here. Unsupported cables D. It says type
MC cable shall be permitted to be unsupported and unsecured where the cable, where
the cable complies with any of the following. All right, we're we got
three conditions that we don't have to support and secure it. Well. The
first one is if you're gonna fish this cable between access points through concealed spaces
in finished buildings or structures, and supporting is impracticals. So this is not
a new installation application. This is remodel retrofit. Whatever you're trying to fish
it in. It just doesn't make sense. You can get from point A
to p A to B through these voids, then this is going to allow
you to do it. Now, here's what's interesting. And I got to
ask this question, and I, you know, I really know how to
answer it because the manufacturers don't test for this. How far can you do
that? And is there a size limitation? What if I want to run,
of shit, I don't know to fifty kc MC through a void?
How far can I run this fished MC cable from point A to point B
before I have a to worry about the weight and the convolutions pulling loose or
whatever. The code doesn't say it really doesn't give us that distance. Okay,
so common sense has to be your here. This is clearly a retro
fit at kind of application. Not I would think not in a new construction,
because to be a finished building or structure, I would think it already
has to be commissioned. CEO is shoot and this is just somebody coming back
trying to add and this is an easy way to get from point eight to
point big A. D two says is not more than six feet in length
from the last point of cable support. And remember we talked about that was
the reason I had to make it clear that the fitting can be considered a
support. Okay, So it says not more than six feet in length from
the last point of cable support the clamp to the point of connection to a
LUMINAIIR or other electrical equipment. Okay, so it's not just luminaires. Might
have another piece of electrical equipment in the space where you're going to be doing
this from and the cable end point of connection are within. An accessible ceiling
doesn't have to be readily accessible, just has to be an accessible ceiling,
right it's above a suspended ceiling, for example, is an accessible ceiling?
I know? Number three D three says is type MC of the is type
MC of the interlocked armor type in length not exceeding three feet from the last
point where it is securely fastened that would be at the connector at the box,
and is used to connect equipment where flexibility is necessary to minimize the transmission
of vibration from equipment, or to provide flexibility for equipment that requires moving after
installation. So you might have a motor application or something like that piece of
equipment that needs that flexibility, or maybe it's gonna creates a vibration and whatnot
and you need that. Well here you as long as it's of the interlocks
type right, and it's not longer than three feet, then it can go
unsupported from the connector, which is considered a support to the piece of equipment,
and that would be perfectly acceptable. Okay, all right, we're gonna
jump to to H three thirty dot eighty and we're almost done. And for
those that are over were watching on TikTok, if you had any questions and
you're posting them in there, I will answer your questions after this session.
So again, for those out there that are following along, this is something
new we're doing and we will answer those questions on TikTok. So post your
questions. I will do my best to answer them after our our podcast.
All right, so three thirty dot eighty ampacity. The ampacity of mc cable
shall be determined in accordance three ten dot fourteen or three fifteen dot sixties.
So three ten dot fourteen's gonna be a thousand volts or least three fifteen's gonna
be over a thousand volts for fourteen and larger conductors, and in accordance with
table four zero two dot five for eighteen and sixteen. So that is going
to be these smaller gauges and dealing with like chords and things like that.
Let's see here, and I don't know that that table is for fixture wire,
by the way, so there's an ampacity associated with that, and that's
what you know. That's just giving you a reference of where you need to
go if you're looking for ampacities for those type of conductors. Most of the
eighteens and things like that that are used in like an mc PCs are you
know, the ampacities are pretty low anyway, they're being used for zero to
ten vote control, and so that's why they're in there, so you're not
really any issue with ampacities for most of the uses for that type of product.
That's called an MCPCS by the way, Uh some companies call it MC
luminary. We call it a donc are. We call that MC LED And
you know what I think. I think South Wire calls it MC duo.
Okay, so all of the same thing. But they're gonna have zero to
ten volt. That's just for the control aspect of it, kind of utilizing
the allowances in seven twenty five to be able to do that, because typically
you can't have class two class three in the same raceway with a power and
power so you have to have a separation. Well, this exploits that by
using MC that complies with seven twenty five because it has thirty mills of sheathing
wrapped around those those zero to ten vault conductors, and so that creates a
separation and that's how we you know, that's how you get around that.
Let's see here. Okay, so MC cable and a cable tray three thirty
dot eighty again is going to send you up to three ninety two dot eighty,
no problem there. Ultimately it's still probably going to send you to three
ten to sixteen anyway, but that's depending on how you install them in a
cable tray. Single type MC cables we talked about earlier. It talks about
that and tells you how you have to center them and all that type of
thing and the configurations and whatnot, and give you some guidance on that and
basic thing I can tell you about ampacities. So the impacity of MC cable.
The inner conductors are typically going to be rated ninety degree from all manufacturers
that make MC cable. It's ninety degree, but you really can't use the
ninety unless all terminals are all equipment it's rated ninety, So we end up
being stuck with the seventy five rated insulation. Now people will say, well
does it one ten, fourteen c one say that it's one hundred amps are
less or fourteen through one that it's got to be under the sixty degree.
That's true. So if I was using that product and I had a weakest
link like a sixty degree rated terminal or sixty degree rated terminal on a piece
of equipment, then that's the weakest link theory. Now, since those conductors
inside of it are actually rated per seventy five really ninety, but since we're
going to realize that we can't use ninety except for adjustment and corrective purposes,
then typically it's gonna be seventy five. Because if you look at one ten
dot fourteen C one, I can't remember if it's C one three or whichever
it is, and I don't feel like going to looking, but that's gonna
tell me. Hey, if the insulation is rated higher than sixty, if
it's at least seventy five, then I can use it at the seventy five
capacities. Again, considering that we have to worry about the terminals and what
their ratings are, but typically the breaker is going to be at least seventy
five, and typically to day the lug on the equipment's going to be seventy
five. So even if it was under one hundred amps, I'm still gonna
be able to use the seventy five five in mccable because of the allowances in
one ten fourteen, C one three or C one A three shiit I can't
remember, but it's it's in there, and go look at it, and
then it's okay to use it at the seventy five it's all about the weakest
link. And we have a video on that called de Rating Demystified. If
you have not watched that video yet, we have a three point zero edition
coming out in a couple of weeks. You definitely want to check that out.
But it's still relevant in the de Rating Demystified. It's probably only available
now over on fasttrackstube dot com. Hey, you know what fasttrackstube dot com
is. That's our exclusive video platform where we have videos that we've all vetted
from different educators and even myself that's available for you to watch up there.
It's amazing deal. One hundred and twenty five dollars annually. You get unlimited
access to it. We have blogs up there too, but you can get
twenty five dollars off by using two five of all capitals now two five off
at checkout, and you can get twenty five bucks off the annual subscriptions hundred
bucks. Dude. There's a series in there for swimming pools that is worth
the money, just that series with me and Vince Della Croach and also we
are scheduled to do a new series for the twenty twenty three on that Here
in a couple of months, he's coming out to the studio and we're gonna
record it like we did. That's gonna be awesome to have him out here.
But we're also have a grounding and bonding series in there that's like twelve
hours long. Okay, four episodes. Look, you're gonna get your money
back and investing in fast Tracks Tube. Trust me. It's and it's getting
better and better. It's we're excited about that platform. Okay, enough of
that. So if you ever wanted to know, or you ever got confused
about the construction of a product, you can always go if withinc you can
go to Part three tells you what conductors are in there. So the hot
conductors, the ground of conduction equipment ground conductors. The minimum conductor sizes shall
be fourteen gauge copper nickel. Okay, how many nickel conductors they have you
ever seen copper nickel, nickel coded copper, and twelve awg or copper clad
aluminum. Okay. The control and signal conductors, minimum conductor sizes shall be
eighteen gauge and a course copper nickel, nickel coded copper and course fourteen of
copper clad aluminum and twelve awg aluminum. Okay, And so you can go
there and look, and it kind of tells you what to expect in your
ear MC cable equipment ground of conductors where type MC cable is used to provide
is used to provide an equipment grounding conductor, it shall comply with two fifty
one eighteen eight ten and two fifty one twenty two. Of course, one
twenty two is what we do to size the equipment ground It's based on the
overcurrent device, right, and in of course two fifty eight eight ten is
part of that list that tells you what qualifies as an equipment grounding conductor,
right, what can be an equipment ground and conductor? And it kind of
gives a list of these items. Okay. Now with mc cable, it's
pretty clear. It says mc cable should be provided with an effective ground fault
current path in accordance with one or more of the following, right, And
there's three here, there's an A B in a C number one. It
says it contains an insulated or uninsulated equipment grounding conductor in compliance with two fifty
one eighteen one. And that's just saying it could be bare covered or insulated,
and that can be an equipment ground, and that's what you usually see
inside of your mc cable. The next one that says the the combined metal
sheathing and uninsulated equipment grounding slash bonding conductor of interlocked metal tape the mc cable
that is listed identified as an equipment ground. So that's the specialty products like
mcap Encore was a smart ground that's a specialty product now that can only go
up to size six conductors, whereas obviously the one with the insulated or uninsulated
equipment ground can go up to two thousand KC mills and larger if you if
you can get it, they'd be So this covers all of that. And
of course the last one that says the metallic sheathing or the combined metal sheathing
and equipment grounding conductor of the smooth and corrugated tube type mc cable that is
listed and identified as an equipment grounding conductor. Okay, so you have just
another allowance for a metal sheath or the combination metal sheath and equip mcgrantic conductor
in the smooth or the corrugated so the metal sheathing in most of those products
will also qualify as an equipment granting contorl Okay. That's most manufacturers again make
the interlocked they don't make the smooth or cork gated. Although they're available,
you can you can go out and get them the most certainly available in the
market. All right, I think that's pretty much hopefully I answered all of
your questions that you had. The only last one that probably need to cover
is if you do have questions on UH insulations, the ratings or whatnot,
then three thirty dot twelve talks about insulation. Three thirty one sixteen is talking
about the sheathing, and that's where you can get kind of some additional information.
That says metal sheathing schell be one of the following smooth metallic sheathing,
corrugated metallic sheathing, or interlocked metal tape armor okay. And it goes want
to tell you the metallic sheathings shall be continuous in close fitting. Says a
non magnetic sheathing or armor shall be used on single conductor okay, so non
magnetic aluminum. It says supplemental protection of the outer covering of corrosive resistant material
shall be permitted and shall be required where such protection is needed. So that's
PVC jacketed MC. So that's where you get your instructions for that. And
at three thirty one sixteen and it says the sheathing shall not be used as
a current care and conductor. That's a that should be a no brainer.
And lastly, howzardous classified locations were required to be marked mc l HL being
howzardous location, the cable shall be listed and shall be have a gas and
vapor tight continuous corrugated metallic sheath, an overall jacket of suitable polymeric material plastic,
and a separate equipment grunting conductor if you want to create an mc h
L product. Okay, all right, hopefully I've answered your question on all
the things to really know about MC cables. Obviously, if you have any
follow up questions, you know what you can do. All you gotta do
is go to Paul Abernati dot com and reference this episode and maybe rehash the
question you want to ask me, because I don't go back and listen to
episodes, and I'm a one take guy, so I don't do things multiple
times. When I turn the MICA on, I'm just rolling. Okay,
So if you have a question, just go to Paul Abernathy dot com and
feel free to post it and I will answer your question either in a follow
up email or it could be selected for an upcoming episode of Let's Ask Paul.
Until next time, folks, stay safe, God bless Boo Boo booth
as Boo Boo ask both. Nope,