ECN Forum Forums Code Related Discussion NEC & other Code issues stapling romex

we could take this to the 'nith degree by asking if the writing side be visible.

Foca Se,

I have tried recently to always put the flat cable on top to avoid compromising the integrity of the insulation on the 3 wire cables. I've noticed problems with the 3 wire in smaller sizes (#14) being held in Romex clamps too tightly and creating shorts.

Bill

wood shrinks, moves,etc. insulators may not 'break' around rx. I always staples very loose for these reasons.

I thought I would bring this thread back to life.

I was told lately that double cable stapleing violated the bundleing rules.

Article 310.15.B.2.b says to derate conductors according to the number of current carrying conductors.

Say I have 3 cables, each a 3-wire #12. That gives me 9 current carrying conductors, which means I have to derate by 70%

Table 310-16 gives a #12 amp rating at 30 amps. 70% of 30 = 21amps. The maximum o.c. device on this size of wire is 20amp. Is the wire protected? Yes, so what is the problem?

I could do the same for 9 #14 wire (25amps X 70% = 17.5)

As long as I don't go over 9 current carrying conductors in a bundle, there is no problem, is there?

Anyone have problems with the bundleing rules as applied to nm cable?

I would like to forward this thread to the inspector who made this call, after I hear from you all on this.

Thanks in advance.

Rick Miell

excellent comeback Rick

I am wondering why you would staple on edge rather than on the flat? Seems like a bad idea to me. I use the stackers as well as the wire ties with mounting holes for more than two wires.

Rick,
In many cases the grounded conductor is not a current carrying conductor for the purpose of derating, so you can go to 4 3-wire cables and still have only 8 current carrying conductors.
Don

Hey guys, what to here a good one. I hear that RX staples are not UL listed for the application. Did anyone else hear of this?

Does UL list common hardware like nuts bolts screws or staples for use?
I remember bieng told that they do not.

This is where the AHJ and sec. 90-4 (1999 NEC) code comes into effect. The AHJ can and may allow certain things to pass inspection even if they don't meet UL approval.