mc in plastic boxes

[steelersman]

PLastic Keyless, you need to upgrade your clients

nothing wrong with a plastic keyless. In fact I think they hold up better than porcelain ones as sometimes they shatter.

 

[Pierre C Belarge]

I disagree entirely with your interpretation of 314.3.

314.3 is not in Part III Construction Specifications, it is in Part I Scope and General. The significance being is if I as the installer provide bonding between all used entries I have meet the requirements.

If I have one MC entry I have no bonding to do, if I have more than one MC or EMT entry I would have to provide bonding between them, that would easily be accomplished with bonding bushings and a jumper.



NEC 314.3 does not require a specific box, it requires bonding.

314.3 Nonmetallic Boxes.
Nonmetallic boxes shall be permitted only with open wiring on insulators. concealed knob-and-tube wiring, cabled wiring methods with entirely nonmetallic sheaths, flexible cords, and nonmetallic raceways.


1. This Section is applicable. A General Part (if there is a General Part in an Article) is applicable to the entire Article unless some other section number modifies the portions covered in the General Part.

2. Shall be permitted is a mandatory direction given in this section.

3. The positive language of this section does not mention bonding, it mentions wiring methods permitted with plastic boxes. (I skipped the first two wiring methods as they are hardly if ever installed)

4. Both exceptions mention INTEGRAL BONDING MEANS.
Integral means the bonding means will be part of the box, not the fittings.

You can disagree all you like, that is what this forum is about. We need to read what is written.

 

[peter d]

You can disagree all you like, that is what this forum is about. We need to read what is written.

And after reading what was just written, I would still install an MC cable in a plastic box that has a 1/2 k.o. All I have to do is provide the required bonding.

 

[steelersman]

And after reading what was just written, I would still install an MC cable in a plastic box that has a 1/2 k.o. All I have to do is provide the required bonding.

right on pete, you tell 'em.

 

[peter d]

right on pete, you tell 'em.

As I said before, and will say again, common sense is all you need here.

 

[steelersman]

As I said before, and will say again, common sense is all you need here.

agreed.

 

[quogueelectric]

As I said before, and will say again, common sense is all you need here.

Common sense is to use a steel box with MC.

 

[peter d]

Common sense is to use a steel box with MC.

Find one that is listed for a fire rating and then I'll use it. In the meantime, when the Arlington "One Box" is the only one that is listed for that application, and it has a 1/2" KO in it, guess what? I'm installing MC cable into it.

 

[steelersman]

Common sense is to use a steel box with MC.

no actually common sense says use plastic when you can as it doesn't rust. using a metal box is just the norm, but not common sense. It's just what YOU'RE used to.

 

[quogueelectric]

Find one that is listed for a fire rating and then I'll use it. In the meantime, when the Arlington "One Box" is the only one that is listed for that application, and it has a 1/2" KO in it, guess what? I'm installing MC cable into it.

So Now you want to go by listings??

 

[quogueelectric]

no actually common sense says use plastic when you can as it doesn't rust. using a metal box is just the norm, but not common sense. It's just what YOU'RE used to.

Yes I see this done everywhere silly me. :roll:

 

[iwire]

You can disagree all you like, that is what this forum is about. We need to read what is written.

I do disagree, I did disagree and I did read what was written. :smile:

What is written does not say what you want me to believe it says.

4. Both exceptions mention INTEGRAL BONDING MEANS.
Integral means the bonding means will be part of the box, not the fittings.

I agree, integral means the bonding means will be part of the box, not the fittings. No question about it.

But only Exception 2 says integral, Exception 1 says internal which does not have the same meaning.

Take a cruise by 680.24(A)(1)(3) to see an example of the code saying what it is not saying in 314.3

 

[peter d]

Common sense is to use a steel box with MC.

Did you see the example I raised earlier?

Let's say I have an MC cable stubbed outside, and my purpose is to transition that cable to an underground run of PVC conduit.

I can use two type of boxes: a metal 3R can, or a plastic can. If I choose the plastic, because it goes nicely with the PVC conduit, I make all my own holes, and then I install the MC cable into it. I throw a bonding bushing on the cable connector and connect it to the EGC that is present in the MC cable. Done, end of story.

You say that I can't do this because the box isn't listed. I have to use a metal box.

I say nonsense. I say "think outside the box" (pun intended) and get creative. Use your noggin and figure out what's code compliant.

 

[peter d]

So Now you want to go by listings??

Do boxes have listings that say what types of wiring methods can and can't be used with them? I know that a plastic nail-on box does. A PVC junction box? Maybe it does. Regardless, if I bond the metallic raceways or wiring methods then I am code compliant.

 

[quogueelectric]

Do boxes have listings that say what types of wiring methods can and can't be used with them? I know that a plastic nail-on box does. A PVC junction box? Maybe it does. Regardless, if I bond the metallic raceways or wiring methods then I am code compliant.

Ul 514b was 1006 bucks to buy online so I can wait till monday.

 

[peter d]

Ul 514b was 1006 bucks to buy online so I can wait till monday.

Sure. While you're waiting for that listing, I'll be installing MC cable in plastic boxes and feel mighty good about it.

 

[steelersman]

Let's say I have an MC cable stubbed outside, and my purpose is to transition that cable to an underground run of PVC conduit.
If I choose the plastic, because it goes nicely with the PVC conduit, I make all my own holes, and then I install the MC cable into it. I throw a bonding bushing on the cable connector and connect it to the EGC that is present in the MC cable. Done, end of story.

if you only have 1 mc cable coming into that plastic box then I don't see why you would need a bond bushing as it would be bonded by the connector at the panel.

 

[iwire]

if you only have 1 mc cable coming into that plastic box then I don't see why you would need a bond bushing as it would be bonded by the connector at the panel.

Lets say it was MCap, he would need the bond to continue the EGC.

 

[mdshunk]

if you only have 1 mc cable coming into that plastic box then I don't see why you would need a bond bushing as it would be bonded by the connector at the panel.

Exactly, or the 4-square above the ceiling that it dropped down out of. There's no special requirement that the MC armor be bonded at both ends. One or the other will do the trick. If a knockout is about 7/8" round, I don't care what kind of box it is, it's getting a connector put in it.

 

[mdshunk]

Lets say it was MCap, he would need the bond to continue the EGC.

Sure, but that's sort of a special case. Well, maybe not so special going forward... that stuff is making inroads fast.