How many cables (3 wires per cable) can I fit under a 1" metal staple? I'm running 3 15A and 3 20A circuits.

Question

How many cables (3 wires per cable) can I fit under a 1" metal staple? I'm running 3 15A and 3 20A circuits.

Answer 1

You will have to check the Manufacturer's Installation Instructions for the Cable and the Staples (it would also be a good idea to check the UL White Book); the NEC is silent regarding this issue. NEC 334.30 states that Type NM cable must be supported and secured at intervals not to exceed 4-1/2 feet, and that flat (elliptical) cables are not to be stapled on edge.

The Article (334) does state that the cables must not be damaged by the staples or any other means of support, and that the radius at the inner edge of any bend shall not be less than 5 times the cable's radius.

If you are planning on running all of those cables in one "bundle"; change your plans. When running 3-conductor cable in a "network" or "Multi-Wire Branch Circuit", the grounded (neutral) conductor is not counted as a current carrying conductor, as it is only carrying the unbalanced load of the circuit conductors; BUT, you are still looking at 12 current carrying conductors, and when they are run in a group or bundle exceeding 24" in length, then you must derate the Ampacity of each conductor according to Table 310.15(B)(2)(a). 12 conductors must be derated by 50%, meaning you have a maximum capacity of only 12.5 Amps for the #14 conductors, and a maximum capacity of only 15 Amps for the #12 conductors.

Good question.

Answer 2

You don't want to do that. Even two romex cables run

together that way don't cool efficiently.

There are 'multi-cable' fasteners on sale in 6-8 cable capacities. (Red plastic wire looms fastened by a nail.)

perfect for your 'app.'. Neat & quick to install.

Try the local Home Depot.That's where I got 'em'.