Easy Elec Q: Cable staples in 'old work' or not?

[Dan Duperron]

Good day Creekers,

I hope this is an easy one, but my wiring book isn't clear on the subject. I'm getting ready for the rough-in inspection on my shop electrical and getting a bit paranoid I suspect.

And yes, I know that the opinion of my local inspector trumps everything else, including any advice provided here.

The shop is in my existing garage. I'm adding lots of additional circuits for outlets, lights, heater, etc. The garage has walls and ceiling insulated with fiberglass & finished with drywall. I have just spent a lot of time fishing wires so as to minimize openings in the drywall that I'll have to patch.

My wiring book (B&D complete guide) says cables must be attached to framing within 8" of each box. But there is no mention of attaching cables to framing in any of the examples shown for old work scenarios, and it's not shown in the pictures. I will of course attach all cables with appropriate clamps where they enter each box. I'm using old-work blue plastic boxes if that matters.

My question is simple - do I need to rip more holes in the walls and staple cables to studs at each box or not? I sure hope not!

Thanks for any advice.

[John Lifer]

Not an electrician, nor inspector, but I question why you are having a Rough-in inspection well after you are NOT just roughed in?
If NEVER any power in the garage, I'd be willing to bet that he'll want to inspect ALL your wiring. Then again, maybe not.
If you just added lines and not initial incoming power, then you may be ok. As you said, inspector is final.
GOOD LUCK!

[Dan Duperron]

Thanks John. Since this garage is part of the house, with existing walls, insulation, electrical (not enough), the rough-in electrical inspection is done with all wiring in place, boxes mounted, but no devices, switches, or fixtures installed. By this definition my new electrical work is just roughed in at this stage. After I pass this inspection I can install the lights, outlets, & switches and have the final inspection done. The inspector will want to look at all of my new wiring, but there is no reason to look at wiring in place since the house was built - althhough he's welcome to do so.

[Joe Angrisani]

I certainly wouldn't tear into walls before the inspector comes. He may decide differently, but wait for him to say you have to do more work.

[Don Buck]

One suggestion that was offered by my electrican before a rough in inspection - in a multi-gang box our inspector wants to see all grounds twisted together for the rough inspection. The grounds don't need to be trimmed and capped, just twisted to show a common ground inspite that you will un-twist to tie in the pig-tail to join the recepticals.

[David G Baker]

Another potential issue may be any boxes in the garage wall that borders the house. They may need to be surface mounted and wires run in conduit because of the wall is supposed to be a fire resistant wall and any penetration of the wall creates possible access for fire or a supply of oxygen to supply a fire. I made this mistake because I had not heard of the requirement and will have to re wire that wall when I do some remodeling in the garage.

[Rick Christopherson]

Because you fished the NM cable through finished walls, it is not required to be stapled at the normal 4.5-foot interval. It is required to use cable clamps at the junction boxes (paragraph 2 below).


Unsupported Cables. Nonmetallic-sheathed cable shall be permitted to be unsupported where the cable:
(1) Is fished between access points through concealed spaces in finished buildings or structures and supporting is impracticable.
(2) Is not more than 1.4 m (4½ ft) from the last point of cable support to the point of connection to a luminaire or other piece of electrical equipment and the cable and point of connection are within an accessible ceiling.

Contrary to popular belief, the inspector cannot simply invent his own code. Code and local amendments are adopted into law by the governing body of your State/County/City. To do otherwise would violate your State's constitution. That would be the equivalent of a police officer changing posted speed limits of his own volition. However, the officer can issue a citation if current road conditions do not support the posted speed limit, but only because this is already a Law in nearly all locations.

If an inspector states that something is a violation, and you suspect it is not, respectfully request a code reference so you can "learn" about it, or something like that. Some inspectors have been known to "invent" rules when they think they can get away with it, but usually asking them for a reference dispels the alleged requirement. When it comes to creating rules, the inspector is NOT the Authority Having Jurisdiction (AHJ). That's the State Board. Unfortunately, even some inspectors mistakenly think that they are the AHJ.

The NEC doesn't specifically address installation methods in fire resistant walls, aside from a general reference to it. That would be addressed in the building code. I don't know this part of code, but I am pretty confident that you are permitted to install junction boxes in a fire resistant wall. What is usually not permitted is to have back-to-back junction boxes on both sides of the wall.

[Dan Duperron]

Rick! Thank you very much for that definitive reply. You have put my mind at ease. I was hoping someone would be able to quote me chapter and verse from the NEC.

I wondered about fire wall penetrations myself, but since the house was built in 2000 and the builder installed an outlet in the wall adjoining the house I figured that was OK. Your note about avoiding back-to-back boxes is a good one though, whether required by the building code or not.

Thanks again.

[Bruce Wrenn]

You are required to have cable attached with in 8" of boxes. The internal clamp on your "old work box" does this. At least that's been my experience

[Rick Christopherson]

Not to nit pick, but the maximum distance from the junction box to support is 12" (NEC 334.30)