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Add new circuit in Electrical Panel

Posted by junkmailhold (My Page) on
Thu, Feb 11, 10 at 18:52

Here is probably a stupid question for those of you who have done this before, but I am installing a couple of 20Amp dedicated NEMA 5-20 outlets about 2 feet directly below my electrical panel in the garage. I will be using ROMEX 12-2 wire.

My question is, do I have to secure the ROMEX anywhere in between the panel and the outlet box? I know I have to use a cable clamp where the wires run out of the panel, but is that all that is required? Can I just have the wire go directly into the box and then onto screws of my outlet without further tie-down?

Another stupid question I have is about the cable clamp at the panel. Everything I've read says to have the clamp screw be OUTSIDE the panel. I can't do that because the panel is mounted inside wall. Is it ok to screw the clamp into the hole from the inside of the panel and also have the clamp screw to clamp the cable on the inside of the panel?

Sorry if this sounds stupid... but I'm a newbie to this and I figured a two foot run from the panel is a DIY job even for me.


Follow-Up Postings:

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RE: Add new circuit in Electrical Panel

Garage requires GFCI protected outlets. You can put the clamp with fasteners inside, better yet just attach the clamp to the cable first and fish the romex into the panel with the clamp already on it, then just put the lock ring on. For me with all kinds of materials already available, I would use a plastic clamp that can be installed after the romex is already in the box, cable pulls through it and it snaps into the box. Since this is a finished wall, no additional straps, staples, support, etc are needed.


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RE: Add new circuit in Electrical Panel

They make plastic NM bushings that are designed to be snapped into the hole from the inside of the panel/box.


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RE: Add new circuit in Electrical Panel

Cable is supposed to fastened within 12" of a receptacle box. One staple will be required unless the cable is feeding through a stud which counts as fastening.


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RE: Add new circuit in Electrical Panel

"Cable is supposed to fastened within 12" of a receptacle box."

This does not apply to cables fished behind surfaces.
Exposed cables require fastening.

If you use an old work box with drywall clamps the only hole in the drywall needed is to mount the box.

Cut the hole, fish the cable with the connector for the panel already attached into the panel.

Install the lock nut in the panel, then feed the cable into the box device box.

Fasten the box to the drywall and tighten the internal clamp on the cable.

You can even use a regular cable clamp by placing it on the cable if you have box fill issues with the internal cable clamp (same trick as the panel).
You strip the cable jacket long enough to feed into the box opening, slip the box into the wall, pull the cable clamp tight into the box using the wires, then fasten the lock nut.


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RE: Add new circuit in Electrical Panel

Are the garage walls finished? - e.g. drywall. If so, you get an exemption from the stapling requirement if you are fishing the line behind a finished surface. If the wall is open, spring for the whole 3 cent staple.


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RE: Add new circuit in Electrical Panel

Thanks for all the tips. Yes, my garage walls are finished. If they weren't and there was no drywall, this would be a no-brainer job.

One other question I have is about fastening the cable at the box. I will be using an Old Work box to attach to the drywall. Is there a clamp in/on that box for clamping the Romex? I thought the romex just runs into the box via a hole and then screws onto the outlet?


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RE: Add new circuit in Electrical Panel

The plastic/ fiberglass boxes have their own clamp and nothing else is needed. Make sure your outlet is a GFCI outlet.


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RE: Add new circuit in Electrical Panel

"The plastic/ fiberglass boxes have their own clamp and nothing else is needed."

The "clamp" is the little tab in the cable entry hole.
It bands over when the cable is fed and grabs the jacket, preventing the cable form being pulled back out (somewhat).


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RE: Add new circuit in Electrical Panel

What will these outlets be used for?

Hey Spencer, I like the idea of putting the clamp on the wire and then pulling it through, I try to think out of the box but I never thought of that.


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RE: Add new circuit in Electrical Panel

Yeah, I like the idea of putting the clamp on the wire first as well. I never though of that!!

These outlets will be used for yard equipment... i.e. Electric Mower, Electric Blower, Electric Weed Whacker, etc. Whenever I have a couple of them going (I get help to do my yardwork!) and then someone clicks the garage opener, my circuit breaker trips. So I thought I'd install some dedicated circuits. Yes, I know to install GFCIs.

Does this sound ok?


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