1

I have a 200A Square D primary panel mounted 5' off the concrete pad between two studs on the back wall of my garage. I have a 50A CFCI breaker and high quality NEMA 14-50 socket that will be mounted in a 4" deep steel box attached to a stud 4' off the floor ~8' to the right of the panel (center of double garage). My original plan was to use #4 THHN in 1" Reduced Wall Aluminum Flexible Metal Conduit horizontally between the bottom of the panel and the box (I know #4 is not needed, but I have it and the conduit left over from another project). Studs are 2x4 nominal, but measuring them they are 3.25" deep, so the 1 3/8" bore hole though the studs would be 42% of depth violating the 40% max for code, and as I will need to bore through 7 studs I can't double them even if I wanted to).

enter image description here

So I need some help deciding between:

  1. running 6/3 UF (much cheaper than Romex) from the top of the panel though the top plate, 9ft across, then down the stud to the box. For added protection I would encase the down leg to the box in the 1" RWC conduit that I have, firmly attached to the stud. (I believe that NM and UL can be run in conduit where additional mechanical protection is needed).

  2. Running 6/3 MC from the bottom of the panel to the box through the studs. This has a much smaller OD, requiring a 1" bore hole that would be within code on the 3.25" deep studs.

Which is these, or any other approach makes the most sense? What am I missing? I will have the installation inspected so all needs to be to code. Many thanks.

8
  • Why not EMT? You could come straight out the bottom of that panel with an LB (or out the side - even easier) and go straight to the box. 1" EMT would only be 16% filled with 3x 6AWG THHN. You could even use 4AWG if you want and only be at 28% fill. EMT gives you the opportunity to upgrade that circuit in the future, even if you sheath the wall, plus you get to use the conduit as the ground conductor, saving copper and effort.
    – Chris O
    Jul 26 at 21:20
  • 4
    That table is a code violation. Working space in front of a panel must be kept clear at all times, from the floor to about 6’ 5”, 30” wide.
    – nobody
    Jul 26 at 21:52
  • The full story is that this is a family cabin that I use sometimes and want to it up to charge EVs. I hear you on the clutter and plan on moving it to the right to provide clearance to the panel.
    – Seamus
    Jul 26 at 22:15
  • @Chris: I like the simplicity of a single section of 10ft EMT and it would provide better protection and a direct run to the box. Yes 1" EMT would let me use my existing wire, only issue is that the OD is 1.163" (a bit smaller than 1" RWC), but would still need a 1 3/8" bore hole, 42% of measured 3.25" stud depth. If i take the usual assumption that actual depth is 3.5" then I'm at 39% just under the limit. Not sure I want to chance this with the inspector. If I dropped down to 3/4" EMT and bought 6AWG THHN that would work.
    – Seamus
    Jul 26 at 22:32
  • 1
    Thank you for the great comments and suggestions! The NEMA 14-50 is for occasional EV charging use at a shared family cabin. I have a spare 50A GFCI breaker from a hot tub that was removed from my main house which saves the $100+ for a new one. Here's the new plan: single 3/4" EMT run in 1" bore holes from an elbow at the bottom of the service panel straight into the box. I'm going to run 2 live + neutral 6 AWG THHN and a 10 AWG THHN ground. Conduit fill factor is <35%, nothing exposed and good protection from rakes falling etc.
    – Seamus
    Jul 27 at 13:27

0

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.