Surface mount questions

[Lockerbie]

The location where I want to put the NEMA 15-40 outlet can only be done via surface mount since the cable run has to be done along the external wall inside the garage. By code, I need to use conduits. However, the 6 gauge cable is very rigid and I need to run it through several 90 degree elbows at the corner and where the cable comes out from the wall via the basement.
If you have done a surface mount, is there a trick to get the cable through elbows ? Do you have pictures you can post or any link that can help me? Thanks.

 

[jcanoe]

Why not use metal-clad (MC) wiring instead? That is what my electrician used (70ft. run) from the sub panel in my basement up to the attic and over and down to the junction box with a 14-50 in my garage. No conduit required.

 

[Lockerbie]

Why not use metal-clad (MC) wiring instead? That is what my electrician used (70ft. run) from the sub panel in my basement up to the attic and over and down to the junction box with a 14-50 in my garage. No conduit required.

Unfortunately I already bought a reel of cable. I did not realize I could not feed the wire inside the wall until I cut the sheet rock to feed the cable.

 

[MY-Y]

If you are running on the surface, take the wire back. I don't think you are allowed to run NM in a conduit. It would be hard to do even if it was to code.

Why can't you put it in the wall? I had 4/3 run in a finished wall, cutting access holes where the cable had to pass through studs.

 

[neelpsu]

I ran 6/3 in the wall of my garage. Electrician signed off on it and said it was done correctly.

 

[qdeathstar]

I ran 6/3 in the wall of my garage. Electrician signed off on it and said it was done correctly.

In the wall good. on the wall, no. MC cable isn’t good for wet locations, eg, outside.

For conduit, you can’t have more than three 90s. If you need more than three 90s, consider making one of them an LB or adding a pull box. Also, get a fish tape roll. For three 6awg conductors and a #10 ground the pipe should be 3/4 min but i’d run 1”


If you are putting romex in the conduit, that is only OK if it isn’t outside. The inside of the conduit would be a wet location outside and NM is dry locations only. Romex in a pipe for a long run doesn’t make a lot of sense though.

 

[MY-Y]

I wouldn't put romex in conduit. I don't think it's up to code and I'd be very concerned about heat building up. Charging a Tesla is likely a much higher multi-hour current draw than any other residential circuit. The circuit breaker, wire, outlet, and HPWC cord all get warm when installed correctly. This is not a circuit where you should take liberties interpreting code.

You could PM Rocky on this forum for very informed information on this.

 

[Lockerbie]

Thank you for all your responses. I decided that this has become more complicated for me and hired an electrician to do it. He was able to cut a couple of holes on my ceiling in the basement and feed the wire to exactly where we needed it. No exposed wire. Everything is inside the wall.

 

[DonaldBecker]

Is this an interior installation run inside the exterior wall? Or an exterior installation?

If it is entirely on the interior of the garage, is the wall open studs or protected with wallboard?

In some places it's OK to use NM (non-metallic e.g. plastic sheathed) cable exposed in utility spaces, such as a garage. Others require conduit. Some even required metallic conduit, with extra thick ('rigid') conduit where it might be exposed to physical damage.

In other locales you are required to have wallboard for fire protection. Sometimes it's less expensive to just put up wallboard, even when not required for fire protection, simply for lower cost electrical installations.

The typical installation when conduit is required would be individual THWN-THHN-2 stranded wires in a grey PVC conduit. Nominally you could use 3/4" and meet the fill limit, but it will be tight and difficult to pull. 1" conduit is only slightly more expensive and makes the electrician's job easier. The limit is three 90 degree turns between pull boxes, but as a practical matter you don't want that many unless there is no choice. You really don't want a combination of high conduit fill and the maximum number of turns.

 

[qdeathstar]

The wallboard isn’t for fire protection. It is to protect the nm cable from damage. NM cable has to be ran so it’s not subject to damage... surface mount in a garage doesn’t seem to cut it...

 

[Rocky_H]

I don't think you are allowed to run NM in a conduit.

I wouldn't put romex in conduit. I don't think it's up to code

It is allowed by code. I don't know why that myth keeps persisting.

and I'd be very concerned about heat building up.

But NM-B is already downrated quite a bit because the rubber sheathing insulates it, so there is that extra safety margin built in by not letting you use very high amps for it.

@Lockerbie did message me, and I talked about this some.

If you are putting romex in the conduit, that is only OK if it isn’t outside. The inside of the conduit would be a wet location outside and NM is dry locations only. Romex in a pipe for a long run doesn’t make a lot of sense though.

Yes, there are good and valid reasons why you would need to do this sometimes. A lot of people are thinking of an entire wiring run as always being in the same environment for the entire distance. Very frequently that is not the case. It sometimes may need to go through crawlspace, or above ceilings in attic, or inside wall, or on the surface of a wall, or some combinations and transitions of those. And sometimes you want to avoid the hassle of cutting and repairing a lot of sheet rock or having to drill through studs to go sideways.

I am looking at that situation for swapping my outlet for a wall connector I have still in the box. I already have the 14-50 directly below my panel, so it didn't need to go across studs--just simple Romex down inside the wall. For the new setup, to keep it simple and clean and not have to cut sheet rock, I want to use that same opening in the wall point to come out and then go through flex metal conduit up and to the right to the location where I want to hang the wall connector. I think you can use one piece of Romex for that "in wall" and "out of wall" situation.

 

[DonaldBecker]

The wallboard isn’t for fire protection. It is to protect the nm cable from damage. NM cable has to be ran so it’s not subject to damage... surface mount in a garage doesn’t seem to cut it...

In some areas you must have gypsum wallboard, including fully taped joints, in a garage for fire protection. Others allow uncovered studs.

In the latter situation it is sometimes easier and less expensive to meet electrical code by installing wallboard over the wiring, even when when it isn't required for fire safety.

 

[qdeathstar]

In some areas you must have gypsum wallboard, including fully taped joints, in a garage for fire protection. Others allow uncovered studs.

In the latter situation it is sometimes easier and less expensive to meet electrical code by installing wallboard over the wiring, even when when it isn't required for fire safety.

That has nothing to do with the wiring....

 

[gfunkdave]

It is allowed by code. I don't know why that myth keeps persisting.

Probably because the reason people usually want to put Romex in conduit is to run inside a garage or outdoors, and then they're told they can't do that.