surface mount sub-panel on stucco exterior rear knockout

n8huntsman

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Apr 5, 2009
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I want to feed my subpanel, by running #6 or #8 NM from the main, through the wall a few feet, to the back knockout of a surface mount exterior subpanel mounted on a
wall. If I can't put the clamp screws inside the box, what type of strain relief do you use?
 
Can't you clamp to the cable (two clamping screws) before you mount the box to the wall. Then. with the nut off, mount the box, feeding the cable through the back knockout and then secure it to the box with the nut. Just requires a little chipping out of the wall to allow the clamp to live back there.
 
gtemkin said:
Can't you clamp to the cable (two clamping screws) before you mount the box to the wall. Then. with the nut off, mount the box, feeding the cable through the back knockout and then secure it to the box with the nut. Just requires a little chipping out of the wall to allow the clamp to live back there.

I'd still have a similar issue on the main panel side since I dont have access to the back of it either. I thought there had to be something for clamping on the inside of the panel but maybe there just isn't.
 

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JasonLion said:
Why do you need strain relief? I would think that all you need is something smooth that won't cut the cable, like a chase nipple.

I thought code required the wire to be secured so that if it got pulled on somewhere, it couldnt pull out of the breaker or pull the breaker out?
 
I can definitively say that the wires coming into the back off my panel are not clamped at all ... whether that is normal or not?

Posted from my Droid with Tapatalk ... sorry if my response is short ;)
 
n8huntsman said:
gtemkin said:
Can't you clamp to the cable (two clamping screws) before you mount the box to the wall. Then. with the nut off, mount the box, feeding the cable through the back knockout and then secure it to the box with the nut. Just requires a little chipping out of the wall to allow the clamp to live back there.

I'd still have a similar issue on the main panel side since I dont have access to the back of it either. I thought there had to be something for clamping on the inside of the panel but maybe there just isn't.

If the wall is hollow and before mounting the sub-panel, feed a long length of cable through the wall, clamp a strain relief meant for the main box to the cable, pull it back towards the main box and nut it to the main box. Then do as I suggested above and you will have strain relieved both ends of the cable to their respective panels and have the strain reliefs on the outside of each panel.

If there's no "chipped away" space behind the main panel you may have to get creative with a bent screwdriver to clear away a little wall material if it's drywall. If it's plywood, then it would be a tougher job.
 
If its a back to back panel/sub installation I would chase nipple it as well, if the distance is to far for a standard chase then prep the holes, measure and get the right length threaded pipe with 4 locknuts and make your own size nipple and if that's the case use a couple plastic bushings on each side...

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