Thread: Running Wires through attic space using multi-cable staple

I find it necessary to run five Romex cables from one side of my workshop to the other side. I intend to use the attic space to run the cables. This attic will have a simple access, but no ladder or stairs. The area will not be used for storage. I want to attach multi-cable staples to the side of the 2 x 4 bottom chord of a roof truss to keep the process neat. Is this an acceptable method?

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If you put no more than two under 3 staples, 2,2, and 1, and staggered them a few " apart along the side of a truss chord, so they are not all bunched, I wouldn't give it a second glance.

Bunch them under one staple or clamp, an amateur would do that. JMO, I'm not a sparky.

Originally Posted by John Kogel

If you put no more than two under 3 staples, 2,2, and 1, and staggered them a few " apart along the side of a truss chord, so they are not all bunched, I wouldn't give it a second glance.

Bunch them under one staple or clamp, an amateur would do that. JMO, I'm not a sparky.

Thanks, John...I would have been inclined to try and do more than 2 in a staple, and perhaps for smaller wire that would work, but I can certainly see the wisdom in the 2,2 and 1 approach with my 12/2 Romex! I appreciate your opinion!

Originally Posted by Lois Granum

Thanks, John...I would have been inclined to try and do more than 2 in a staple, and perhaps for smaller wire that would work, but I can certainly see the wisdom in the 2,2 and 1 approach with my 12/2 Romex! I appreciate your opinion!

Actually, while two NM cables are permitted under one staple, putting two NM cables under one staple for more than 24" leads to derating the conductor ampacity, i.e., a #14 is no longer rated for 15 amps, a #12 is no longer rated for 20 amps (the derated ampacity depends on the number of conductors and the temperature of the attic.

So, in proper practice (in addition to meeting code) you should have all three cables side-by-side-by-side with a small space between them (the staple legs of each staple provide that small space).

Just like one can install 6 conductors in a single conduit, one is supposed to derate as required. Not saying that everyone does it, or even that many do it, but when inspection time comes - the inspector should look at it and do the derating ... at which time redoing the work is a lot more work than doing it correctly the first time.

Avoid any derating pitfalls - place each NM cable side-by-side-by-side, each under its own staple.

And, any cable within 6 feet of the attic access opening needs to be protected if not along side the truss (such as running over the trusses and stapled to the truss edges).

Originally Posted by Jerry Peck

Actually, while two NM cables are permitted under one staple, putting two NM cables under one staple for more than 24" leads to derating the conductor ampacity...

Jerry, I have considered using the staple shown below, which would hold up to 4 wires out away from the 2 x 4 truss member. This work will be inspected and I want to meet code the first time! Would this meet the separation requirement and maintain ampacity? It is about a 20 foot run across the room. Thank you for your help...

Originally Posted by Lois Granum

Jerry, I have considered using the staple shown below, which would hold up to 4 wires out away from the 2 x 4 truss member.

Those aren't "staples", however, if you use those you should be good to go as those were designed to eliminate the problems mentioned (allows more than two NM cables and spaces the cables apart from each other ... those eliminate the need to derate for lack of maintaining spacing. NM (actually NM-B) cables are already 'uprated' to account for most attic temperatures and derating basically only becomes a problem when spacing is not maintained.

Those clips/supports should solve your problem.

Originally Posted by Jerry Peck

Those aren't "staples",
Those clips/supports should solve your problem.

I just found that product at Home Depot. They are labeled "Gardner Bender Multi-Cable Staples ", thought I believe they would be more properly labeled "clamps"...thanks for your input. I'm headed to the workshop now!