# MC and Plastic Boxes



## Bird dog (Oct 27, 2015)

I did a quick check and kind of doubt it. Only listed for ENT.

http://www.homedepot.com/p/4-in-PVC-Square-ENT-Outlet-Box-10-Pack-A5217DE-CAR/206985887


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## hardworkingstiff (Jan 22, 2007)

http://forums.mikeholt.com/showthread.php?t=96937


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## hardworkingstiff (Jan 22, 2007)

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.

Exception No. 1: Where internal bonding means are provided
between all entries, nonmetallic boxes shall be permitted
to be used with metal raceways or metal-armored cables.

Exception No. 2: Where integral bonding means with a
provision for attaching an equipment bonding jumper inside
the box are provided between all threaded entries in
nonmetallic boxes listed for the purpose, nonmetallic boxes
shall be permitted to be used with metal raceways or metalarmored
cables.

So, I would say if you had a means to bond all of the MC cable sheaths together, you could do it.

For receptacles, going in/out of one box, could you use one of the MC connectors that accepts two cables but only uses one KO in the box and comply with the bonding requirements? Do they make one of those connector that accepts three cables? IDK.


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## MechanicalDVR (Dec 29, 2007)

I've seen it 100 times never figured it was within code to be there.


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## telsa (May 22, 2015)

Be prepared to buy a LOT of bonding bushings and two-screw MC connectors.

You'll have to route bonding connections through every active KO.

The labor involved would break the bank.

Snap-in MC connectors would be red-tagged.


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## MechanicalDVR (Dec 29, 2007)

hardworkingstiff said:


> 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.
> 
> Exception No. 1: Where internal bonding means are provided
> ...


*I think that's a winner right there!*

*Not that I have ever come across!*


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## Chris1971 (Dec 27, 2010)

backstay said:


> Can you mix MC and plastic boxes? I have a job where plastic boxes with knockouts would work better than steel. Just never thought about it and I've never seen it.


PM Dennis Alwon.


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## backstay (Feb 3, 2011)

Like most on here, I "knew" it wasn't right. But I don't know everything!


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## hardworkingstiff (Jan 22, 2007)

backstay said:


> Like most on here, I "knew" it wasn't right. But I don't know everything!


When I first read your question, I was like .... well, I want to say no but I'm not sure why.

Google let me find answers, lol.


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## FF301 (Jan 12, 2014)

I think it is Arlington electric that makes a washer with a pig tail that you place under the locknut to bond " entrance " ( MC or pipe) together when using plastic boxes.


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## splatz (May 23, 2015)

backstay said:


> Can you mix MC and plastic boxes? I have a job where plastic boxes with knockouts would work better than steel. Just never thought about it and I've never seen it.


Just curious about your job, what would make plastic better?


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## backstay (Feb 3, 2011)

splatz said:


> Just curious about your job, what would make plastic better?


The wall covering thickness is up in the air. I use an adjustable plastic box in my residential work. But I set steel boxes with mud rings. They get what they get now.


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## splatz (May 23, 2015)

backstay said:


> The wall covering thickness is up in the air. I use an adjustable plastic box in my residential work. But I set steel boxes with mud rings. They get what they get now.


Arlington does make an adjustable metal box: 

http://www.aifittings.com/products/spec-sheets/FA101.pdf


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## backstay (Feb 3, 2011)

splatz said:


> Arlington does make an adjustable metal box:
> 
> http://www.aifittings.com/products/spec-sheets/FA101.pdf


I didn't know that, too bad it only comes in one gang. 

Thanks Splatz!


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## RePhase277 (Feb 5, 2008)

Use a bonding lock nut and jumper.


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