Grounding NM connectors????

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Dennis Alwon

Dennis Alwon

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Retired Electrical Contractor
I guess the big question is what is likely to be energized? If I have NM cable and use metal connectors to attach to a PVC JB is the connector likely to be energized. My gut tells me that this is an illegal install yet I see it all the time with in line plastic fans.

If the connector is likely to be installed then why would a staple not fall into the same category. The connector is only likely to be energized if you over tighten the screws in much the same way that a staple may be energized from smashing the dang thing too hard.

Any art. that specifically calls for all metal connectors to be grounded?
 
stickboy1375 said:
I know what your question was.... and IMO, a connector is not likely to become energized. but if you feel it is, use a bonding bushing.
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I generally use plastic connectors in this scenario but I ran out the other day and reluctantly used a few metal ones and was curious about the issue. I would change the metal connectors before I used a 1/2" bonding bushing. :smile:
 
Here is what the NEC stlye manual has to say about what the term "likely to become energized" means.

likely to become energized -- failure of insulation on
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After reading that I believe that the connector in question would be likely to become energized.

JMHO,

Chris
 
bphgravity said:
If used properly, I wouldn't give a metallic connector used with NM and a non-metallic box a second thought.
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The problem I see with that is how do you know if it is used properly. A connector tightened slightly too far can energize the metal and you would not know it and it would not short the circuit. There lies the problem in my eyes.
 
Grounding NM connector

Grounding NM connector

I had an apprentice that over tightened everything. Once he broke a acorn clamp on a ground rod,while we were out of state and it was the only one we had.

He tightened nm connectors to a point where they would short out.

It got so bad That I had to check all of his connections. Would have fired him but it was the owners son.

I think that a nm connector on a plastic box is more likely to become energized than a metal plate but we are required to bond a metal wall plate.I think there may be the same requirement for a connector some day.
 
Grounding NM connectors

Grounding NM connectors

iwire said:
I have never seen a metal kelllem grip grounded when used from a building structure or cord cap. :smile:
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The Kellem grip is listed for the purpose and the ones I have used had no way to over tighten them.
 
romeo said:
The Kellem grip is listed for the purpose and the ones I have used had no way to over tighten them.
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NM connectors are lised for the purpose.

When someone plays Tarzan with a cord drop suspended from a building mounted kellem it 'over tightens' plenty. :smile:


If someone puts in substantiation that shows real evidence of this long time practice being a hazard I will support it, but I can't support 'I think it is likely, maybe, sometime, it might become energized. :smile:
 
iwire said:
I have never seen a metal kelllem grip grounded when used from a building structure or cord cap. :smile:
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Neither have I.;)

My question is, after reading what the NEC style manual has to say on the subject of "likely to become energized", it brings into question alot of things that due to insulation failure would become energized.

Until Ryan pointed out the what the NEC style manual said I had a different view of "likely to become energized."

Chris
 
raider1 said:
My question is, after reading what the NEC style manual has to say on the subject of "likely to become energized", it brings into question alot of things that due to insulation failure would become energized.
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I agree, you can read that in a way that leads to the conclusion that anything conductive in the world could become energized.

But we don't bond all conductive items except around a pool.
 
iwire said:
I agree, you can read that in a way that leads to the conclusion that anything conductive in the world could become energized.

But we don't bond all conductive items except around a pool.
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Heck, look at how many table lamps are metal or at the very least have a metal clad socket, and they only have a 2 wire cord. I realize that portable lamps are outside the scope of the NEC, but you get my point.
 
What about a metallic blank cover on a plastic box? I see that all the time. Is it likely to become energized....I think not.
 
A/A Fuel GTX said:
What about a metallic blank cover on a plastic box? I see that all the time. Is it likely to become energized....I think not.
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And I know an EC that got called on that. He had to ground the plate-- this was before we had the round plastic blanks for lights.
 
Grounding NM connectors

Grounding NM connectors

iwire said:
NM connectors are lised for the purpose.

When someone plays Tarzan with a cord drop suspended from a building mounted kellem it 'over tightens' plenty. :smile:


If someone puts in substantiation that shows real evidence of this long time practice being a hazard I will support it, but I can't support 'I think it is likely, maybe, sometime, it might become energized. :smile:
Click to expand...

I do not disagree, but I thought we were talking about NM cable,(romex)I have never seen romex used in the the manner you discribe.

If I were still working in the trade I would use plastic connectors and not have to give it anymore thought.
 
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