# Metal Connectors



## highlife77 (Oct 21, 2005)

Is it safe (code) to use a metal connector in a plastic box?? Is it okay to run MC (greenfield) into a plastic box??Thanks.


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## Mark Twenhafel (Dec 23, 2006)

This new guy says probably so:Art. 314.3 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 metal-armored cables.
_​Sounds like all you need is a do-hickey fitting that allows you to bond the cable armor of all entries into the box.


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## JohnJ0906 (Jan 7, 2007)

highlife77 said:


> Is it safe (code) to use a metal connector in a plastic box?? Is it okay to run MC (greenfield) into a plastic box??Thanks.


Are you using MC cable or Greenfield? Different creatures.

MC cable comes with the conductors, Greenfield is a flexible conduit that is installed, then the conductors are installed.


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## Speedy Petey (Sep 30, 2003)

More likely probably NOT.

When was the last time you saw a plastic box with: 1) an _internal bonding means are provided between all entries
_or 
2) an _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

_These are very specialized plastic boxes. Not the ones you see on the shelf at Home Depot.


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## Mark Twenhafel (Dec 23, 2006)

Speedy Petey said:


> More likely probably NOT.
> 
> When was the last time you saw a plastic box with: 1) an _internal bonding means are provided between all entries
> _or
> ...


Okay, thanks, AGAIN, Speedy Petey. I'm going back to stealth mode, now.
Peace out, bro.


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## Magnettica (Dec 19, 2006)

Are these boxes listed and identified for the use connecting Metal-Clad Cable?

NEC 330.40


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## Speedy Petey (Sep 30, 2003)

330.40 is referring to the fittings. Not the boxes.


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## mdshunk (Mar 13, 2005)

I think there might be a few instances where you an use a metallic raceway or cable system with nonmetallic boxes by utilizing the exception 1 with ordinary plastic boxes with knockouts. 

Exception 1 requires that the conduit or cable entries have _internal_ bonding (inside the box), as opposed to the _integral_ bonding (built into the box) required by exception 2. If you have only one cable entry, then no internal bonding is required (duh, no other cables or conduits to bond over to). If you have more than one cable or conduit entry, there are a variety of fittings available that you might use. A bond bushing comes to mind, for instance. 

Matter of fact, Arlington's version of the Smart Box (I think they call it the "In Box") is fire rated, making it an ideal old work solution for old work in a commercial building. This box features standard sized knockouts, as opposed to NM cable clamps, making it suitable for use with MC cable within fire rated assemblies.


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## neolitic (Apr 20, 2006)

Welcome home!:thumbup:
You wuz missed.


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## Magnettica (Dec 19, 2006)

330.40 *Boxes* and Fitttings


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## Speedy Petey (Sep 30, 2003)

Magnettica said:


> 330.40 *Boxes* and Fitttings


OK. READ the text son.

_*330.40 Boxes and Fitting*
Fittings used for connecting Type MC cable to boxes, cabinets, or other equipment shall be listed and identified for such use._


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