MC Cable through Metal Studs

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infinity

infinity

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After reading 330.17, IMO MC cables through holes in metal studs do not require the 1.25" spacing from the stud edge. 330.17 references 300.4(A) which is for bored holes in wood. The job in question involves MC run through the punched holes in 1 5/8" studs. Any opinions?
 
I tend to agree also however, what about the first sentence in art. 300.4. Where subject to physical damage conductors shall be protected.

It does not say shall be protected by A thru F. I t could be a stand alone that covers all.

How would you protect the mc cable passing through a metal stud-- nail plates screwed to the stud???
 
MC

MC

I agree with Dennis, 330.17 ref. you back to 300.4(A), (C), and (D), but I believe 300.4 is the catch all. Where subject to physical damage, conductors shall be protected. A - F are examples when and how. JMHO
 
Jim W in Tampa said:
And a drywall screw will go thru it like butter.Unless you enjoy replacing wires you better treat it like romex.
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Gee Jim, thanks, I did not know that. :D

But that means nothing to me, the NEC considers schedule 80 PVC to protect conductors from damage.

A drill point drywall screw will pass right through EMT but we don't have to put nail plates on that either.

IMO, we are not required by the NEC to put nail plates over MC.

With respect to John I feel he is asking for more than the NEC requires.
 
protect MC

protect MC

I tend to agree with Dennis. The 1st senrtence of 300.4 states they shall be protected. (A) discusses wood members. Subsequent sections point out the need to protect conductors excluding RMC, IMC, RNMC and EMT. To me, if the MC wasn't 1-1/4 from the edge it wouldn't be considered protected.
Just my opinon. As an inspector, I have not encountered that actual situation except parallel to the framing members and I do require the 1-1/4.
Persoanlly, I'm actually suprised that the Code exempts RNMC and EMT.
 
iwire said:
A drill point drywall screw will pass right through EMT but we don't have to put nail plates on that either.
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I recall a panel response to a proposal that the reason for that was that the screw could be removed, and then undamaged conductors could be pulled in the EMT. Cable assemblies do not offer that option.

Why is MC treated differently than NM? :confused:
 
augie47 said:
The 1st senrtence of 300.4 states they shall be protected. [snip] To me, if the MC wasn't 1-1/4 from the edge it wouldn't be considered protected.
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Augie, the problem I have with that is that 300.4 is extremely broad. What is your basis for so exact a measurement as 1.25" to determine protection? ;)
 
I would kick plate (nail plate) this situation but have also seen drywall screws well into a kick plate. IMO, I would spend a couple bucks on rough than cut the wall on hot check.
 
protection

protection

George,
I enjoy that you both inform me and make me think.
The panel discussion regarding cable assemblies vs conduits is enlightening and sorta a "Duh!" to me. Every day I'm reminded how many folks are so much sharper than myself.

In reagrd to the 1-1/4, I realize it's presumptious on my part, but this is the number used throughout 300.4 for protection of cables and conduits so I don;'t feel that I'm just pulling it out of the air. I realize it might be a case of my overstepping the bounds, but its somewhat of a common sense issue, IMHO. As I say, I don't recall I've ever actually seen the problem on "punched" holes in metal studs.

Sometimes you stir my settled (and stubborn) ways :) thanks
 
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I say the 1 1/4 measurement that Augie is speaking of is referenced in 300.4(D)Cablesand Raceways Parallel to Framing Members and Furring Strips

This is also where I would take inference that MC installed through metal framing would also need to be at least 1 1/4 inch spacing from the front edge of the metal framing.
 
iwire said:
Gee Jim, thanks, I did not know that. :D

But that means nothing to me, the NEC considers schedule 80 PVC to protect conductors from damage.

A drill point drywall screw will pass right through EMT but we don't have to put nail plates on that either.

IMO, we are not required by the NEC to put nail plates over MC.

With respect to John I feel he is asking for more than the NEC requires.
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So what are you sugesting here Bob ? Dont protect it and just hop you dont get hit ? WOW thought you were smarter than that.
 
Jim W in Tampa said:
So what are you sugesting here Bob ? Dont protect it and just hop you dont get hit ? WOW thought you were smarter than that.
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What Bob is saying is that protection is not required. If you as an installer choose to roll the dice that's your own choice. Personally we almost never use protection plates on metal studs.
 
infinity said:
What Bob is saying is that protection is not required. If you as an installer choose to roll the dice that's your own choice. Personally we almost never use protection plates on metal studs.
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Been hit to many times to even think of going that route
 
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