New circuit in unfinished basement: can I run NM along the beam?

[Joey_P]

@Mdcastle

I don’t see anything wrong with the pictures from a code point of view.
From a practical point of view I might be afraid of a ladder being leaned on it. If I were doing it I’d probably run it along the beam and then nail a 1X2 below it.

I don’t know about code, but I’m not fond of that junction box being mounted on a shelf. Imagine someday if the shelf falls, it’s going to tear the box down with it. Worst case scenario, it opens up a splice and energizes an ungrounded box, or leaves wires hanging out that someone grabs.

Why isn’t that box mounted to the wall instead?

[Rhythmdvl]

Thanks for the input. I don’t know about replacing all the existing staples (kind of a if-it’s-not-broken thing), but it’ll take two extra seconds and two extra dollars to nail a 1x2 below the run.
The box on the shelf isn’t quite a box, it’s a power strip similar to this. When doing this I had inspectors out before (they were nice enough to come out and discuss plans) and after, and pointed out all my ‘weak’ areas and things I wasn’t completely sure of—and this installation was one of them. They were great, recognizing that since I didn’t need the inspection per se (no town requirement) and that all my concerns were safety-related, they took an interested and avuncular approach to giving me advice and reviewing my work.

And sturdiness-wise, the shelf is mounted to the brackets with three screws each, and the brackets are directly sunk into the wall with three Tapcons each. Tapcons are also holding the EMT leading to it (close to the shelf). Finally, the brackets are oversized for my use (it’s a charging station), but I put in the 1000-pound (or was it 500?) rated brackets because who knows what may happen down the line.

[Tim_T-Bonham.net]

@engineer_comp_geek

Conduit, being enclosed, doesn’t allow water to evaporate very easily. Any moisture from condensation or anything else will tend to collect in the conduit and will stay there for a long time. The insulation on NM cable isn’t rated for moisture.

The NEC does allow you to run NM cable in conduit if it’s not in what the NEC calls a wet or damp location. Local codes may vary.

It’s a common belief (but not in the NEC) that running NM through conduit could cause the wire to overheat under high current loads since NM cable expects to be able to dissipate heat to the open air. Personally, I’m not sure about the validity of that one. It seems to me that the insulation on NM cable already provides pretty good thermal insulation and I doubt that the conduit around that would make much difference. That’s the reason that a lot of folks will tell you, though.

Another reason not to run NM cable inside EMT is that it is a waste of money.

With NM cable, you are paying for heavier insulation, paper cladding, and the outside cable sheath all to protect the conductors. Then you are paying for an EMT tube around that, also to protect the conductors inside. You are needlessly duplicating the protection, and spending more money to do so. THHN wires inside EMT is much cheaper. Why waste money?

Actually, for a home handyman, the costs may not matter.
For a short section where you’re using EMT for protection, you probably have the NM cable available, while you would have to go out and buy THHN wire. So you can just use the NM inside EMT. Or you could strip the outer NM sheath off the wires, not just for the 6-8 inches inside the box, but the several feet that is inside the EMT. It’s not hard to do, and then you have loose wires running through the EMT – that leaves you more room if you ever want to add circuits someday.

[Mdcastle]

The second set of pictures:

1. It looks like there isn’t a staple within 12" of the box.
2. You can’t run romex over concrete, so the short run to the light should be conduit.

It would be better to make the transition on the beam and then have a 90 degree conduit bend to transition to the wall.