I'm planning on running a 6/3 feeder cable from my main panel to the garage for a small 50A subpanel and am unsure of how to plumb the new cable to the main panel. All of the knockouts are on the bottom of the box, and I want to run some conduit from the panel to the attic along the exterior wall. Rather than adding a couple of elbows in order to run the conduit from the attic to the knockout on the bottom of the box, can I drill a new hole in the side of the panel, near the top for the 1" conduit? I imagine I would need to use an LB here and at the attic entrance?

Here's what I am thinking:

main panel

main panel 2

main panel 3

  • 4
    I think exterior panels favor knockouts on the bottom to reduce the risk of seepage.
    – bib
    Commented Mar 19, 2017 at 2:10
  • Can you post a close-up of the panel's insides? There may be something larger afoot here...but I can't tell for sure Commented Mar 19, 2017 at 2:11
  • If you are going to run conduit, use individual wires, not 6/3 cable.
    – Ecnerwal
    Commented Mar 19, 2017 at 2:18
  • @bib, that makes sense. Does that mean I can't use a weathertight connector on the side?
    – RoccoC5
    Commented Mar 19, 2017 at 2:46
  • @Ecnerwal, I was under the impression I could run cable through conduit for short runs such as this? It's only 5 feet to the attic and I hadn't planned on running any conduit through the attic.
    – RoccoC5
    Commented Mar 19, 2017 at 2:47

1 Answer 1


Go out the bottom, otherwise the hole or any flaw in the conduit will bring water, rust and failure into your box.

Use two conduit bodies to make your 180 degree turn. You can do this pretty tight to the box surface if you really want to. Do not strap the conduit to the box, strap it to the wall.

Use THWN-2 wire in the cable. This is rated for outdoor wet locations like this location. Use stranded, you sure don't want to pig-wrestle solid #6 (least of all 4 of them in a cable!)... and stranded will make the bends easily and pull decently. If you don't want to buy 4 colors of wire, buy white - shuck it for ground and put tape on it for hot.

Why white, by the way? Because of the rules applicable to re-marking wires smaller than 4 AWG. You cannot re-mark any color of wire to be ground, it must be green, green/yellow, or bare. You cannot re-mark any colored wire to be neutral - it must be natively white or gray. You can re-mark a white or gray to be a hot, that is the only re-marking allowed (it's intended for switch loops). Admittedly, shucking a stranded wire for ground may not work - but they sell single bare solid ground wire at modest cost.

  • 1
    Will do +1 if you can explain why using white color for all conductors and then marking the ungrounded conductors black, and skinning the ground to bare is actually legit . -- I know why..just would like to see it in the answer :-)
    – Kris
    Commented Mar 19, 2017 at 16:24
  • 2
    @Kris you got it :) Commented Mar 19, 2017 at 17:09
  • Thanks for the reply. Since I can't run the romex in conduit, Can I run the individual wires through the conduit and splice them to the cable once inside the attic? Or can I strip the sheath off of the NM cable for the conduit run?
    – RoccoC5
    Commented Mar 19, 2017 at 17:57
  • 2
    @RoccoC5 You can't run NM at all in wet locations, so that's out. You can't use unsheathed conductors for anything more than a pigtail (because they are not marked as to type, NM with marked THWN-2 inside would be marvelous, but mythical). Just install a junction box where you make the transition from conduit to romex, and make the splice there with wire nuts. Commented Mar 19, 2017 at 18:50
  • @Harper ... Awesome
    – Kris
    Commented Mar 19, 2017 at 22:04

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