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#88966 - 08/19/04 05:18 PM Protecting NM cable with wood members
jes Offline

Registered: 07/12/02
Posts: 103
Loc: CT
Two questions re. 300.4 and 550-15(C) (and similar)
First, for cables passing through wood members and without the required 1 1/4" setback: Has anyone experienced problems with sheathing fasteners (power driven staples or nails) missing the studs (and the protective plates for NM cable) and penetrating the cables?? As I read the NEC the plates DO NOT have to extend beyond the edges of the studs.

Second, 300.4(D) for cables PARALLEL to the studs and without the required 1 1/4" setback there appears to be an additional requirement for plate protection: If protection extending beyond the stud edge is required in this case where misdriven fasteners can impact the cable why not at drilled holes or notches?? What am I missing??

2014 / 2011 NEC & Related Books and Study Guides
#88967 - 08/19/04 05:47 PM Re: Protecting NM cable with wood members
earlydean Offline

Registered: 12/22/03
Posts: 749
Loc: Griswold, CT, USA
You have missed nothing. The NEC has missed it. It seems as if someone needs to raise this omission with a code submittal.

#88968 - 08/20/04 01:48 AM Re: Protecting NM cable with wood members
iwire Offline

Registered: 01/05/03
Posts: 4343
Loc: North Attleboro, MA USA
Jes If you are having problems with this happening to your cables go ahead and add additional protection nothing says you have to wait for the NEC.
Bob Badger
Construction & Maintenance Electrician

#88969 - 08/20/04 04:39 AM Re: Protecting NM cable with wood members
Joe Tedesco Offline

Registered: 10/07/00
Posts: 3325
Loc: Boston, Massachusetts USA
Hi Jes:

I was reminded of a proposal I sent in early in the 1990's.

I asked for the code to be changed to add 1/4" on each side of the "Kickplate" and CMP 3 said that was intended with the words I have bolded:

300.4(A)(1) Bored Holes.

...... Where this distance cannot be maintained, the cable or raceway shall be protected from penetration by screws or nails by a steel plate or bushing, at least 1.6 mm ( in.) thick, and of appropriate length and width installed to cover the area of the wiring.

This is already included according to the panel, but now we have all new members and a new Chairman who may agree with replacing those vague and undefined words really not permitted by the style manual anyway.
Joe Tedesco, NEC Consultant

#88970 - 08/20/04 05:02 AM Re: Protecting NM cable with wood members
earlydean Offline

Registered: 12/22/03
Posts: 749
Loc: Griswold, CT, USA
hear, hear

#88971 - 08/20/04 09:32 AM Re: Protecting NM cable with wood members
gfretwell Offline


Registered: 07/20/04
Posts: 9026
Loc: Estero,Fl,usa
How do you all feel about the standoffs they use to hold Romex 1.25" to the side of a furring strip on a 3/4" furred masonry wall void?
The standard practice used to be to sleeve the Romex in EMT where it was unable to be 1.25" back. Now they are just using the plastic standoff to get a horizintal separation.
I can understand that the rocker will probably hit the furring +/- 1.25" but a homeowner hanging pictures might just keep poking holes until they hit something solid.
Greg Fretwell


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