I'm installing a NEMA 14-50 in the garage with a dedicated 50amp breaker. I have run the 6/3 romex through the attic and am at the point where I'd exit the attic to the exterior of the house and down to the main panel. I am realizing that I'm not 100% sure how to enter our main breaker panel.
I had planned to use a short run of EMT from inside the attic to exterion, LB conduit body to transition down the exterior wall and then into the top of the panel. My understanding is that code allows me to run romex in the conduit (up to 10ft) and that I must enter the top of the panel. (reference: Can Romex (NM-B) be run through conduit?)
My panel has a ~2×2 square plate on the top. I don't know how to terminate the EMT in a rain tight method. Here's a picture of the top of the panel and general overview of the setup before I've done anything. How can I terminate the EMT in the panel and ensure it's watertight?
Best Answer
You can't run NM in an outdoor conduit
NM is not rated for wet locations. Any exterior conduit is a wet location, so NM can't go there. Besides, getting NM to go down conduit is more of a pain than you want or need.
Running into the top of the panel is unwise
Running a conduit into the hub at the top isn't the wisest idea, to say the least -- that hub is intended to be used for a service mast with its attendant weatherhead to keep the rain out, not a conduit going up into a LB, and you can't have any other openings in the top, or else the box loses its NEMA 3R weathertightness rating.
Instead of that, I would use a box to transition to 6AWG THWN in 3/4" EMT in the attic, then run the EMT out of the house and LB the run down to a LR body that goes into the right side of the box, right above where the service wires go in. Also, put a 1/8" hole in the bottom of the LR to make sure that water can get out of it instead of building up and then going off into your panel.
Having the meter pulled for at least parts of this is a good idea.
I'd have the meter pulled for this on two occasions:
If you leave the cover off the LR, you can do the rest of the pull with the power still on. If any of this makes you uncomfortable, of course, simply poke your favorite electrician.