My house has a older panel that I am running a 1/0 SER cable to my garage (attached by a breezeway, with a attic).

My problem is running the SER cable to the BACK of the already installed main panel (running to garage for a sub panel) I have cut out the drywall behind the panel (which is outside and set into the t1-11 siding).

I am dropping the SER from above into the wall cavity behind the panel. There is only one spot to put in the cable, and it's in the back. There are no spots on any side.The panel is 30 years old and is one box, with a separator and the meter on the left, with the main line coming through in the center left.

My question: There is only two inches between the back of the panel and the drywall, so a LB will not work. Can I run the individual lines through the punched out 2" hole and not use an LB?

Main panel

enter image description here

  • 1
    Why can you not run the cable out the top or the bottom? Commented Sep 8, 2021 at 0:09
  • so the meter is on the right looking from the back?
    – Jasen
    Commented Sep 8, 2021 at 4:21
  • 1
    @Jasen see link above picture "Main panel" Commented Sep 8, 2021 at 5:06
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    Can you show us the bottom of the panel. That looks like the only place you could enter since the back will never get the inner edge of cable bend minimum radius of 5x the cable diameter (NEC 338.24). Commented Sep 8, 2021 at 5:11
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    What's up with the rags stuffed in at the bottom of the box on the interior view? Also, on the interior view, is that a piece of NM-B on the right of the stud to the right of the panel? If so, that doesn't appear to be attached properly and it would be very easy for a screw for the replacement drywall to miss the stud and go right through the wire, causing a short and giving you one heck of a zap.
    – FreeMan
    Commented Sep 8, 2021 at 14:03

1 Answer 1


You need to keep the cable intact until it passes through the clamp as it enters the panel, or a junction box, so you can't split out the individual conductors. Conduit bodies are not junction boxes. You can't hide an LB behind drywall

If there's room, make a hole in the top of the panel and enter there.

If you have to go in through the back use a junction box, connect the junction box to the panel with a conduit nipple, clamp the wire where it enters the junction box, then you can then separate the conductors and pass them individually into the panel through the nipple.

If you picked the right junction box it will end flush with the drywall and you can close it with a blank cover plate. You're not allowed to hide JBs behind drywall either.

You're allowed punch holes in junction boxes to connect them to things, same as panels.

  • They can't use an ordinary JB for this -- a 1/0 cable will require a pull box of some size in order to make the bend Commented Sep 8, 2021 at 23:25
  • 1. the rags block a air hole to the outside. 2. To run through the top, I'll have to move three sets of 14 gauge romex and double them up where they go in the box, I can do that and then rent a whole puncher. 3. the right half of the box is unusable to run wires in because it leads to the service meter and crossover. 4. A pull box is another option that I can use, as I don't really care if it shows on the wall inside the utility room where the back of the panel is. 5. Thank you all for helping!
    – John H
    Commented Sep 9, 2021 at 15:16

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