This is in my garage. I am trying to add a second circuit in order to be able to run the dust collector and the table saw at the same time. I did run them on the existing circuit with no load and the breaker did not trip but I want o be on the safe side.

There is one circuit that enters the garage right where you see the GFI power outlet. I extended that to a workbench that I have to the left of the door on the left side (conduit not shown) and to the right to feed the garage door lift and to add one more power outlet also connected with a wire run through plastic conduit. This circuit is grounded.

Now I have wiring coming into the garage from the porch then it is run as seen down to the bottom level of the first garage front light. The cable goes into the wall outside to feed that light bulb and then it comes back it goes above the garage door opening and it lands on the other side of the garage door (not pictured) to feed the other garage door light (extreme right of the picture) The above are on a 15A circuit that has a on/off switch in the house.

Can I run a ground wire from the power outlet that is next to the new power outlet that I want to add (highlighted in blue)?

..all my regular circuits are 15A ..

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  • so short answer is yes, extend the ground wire of the grounded circuit into the box of the new power outlet?
    – MiniMe
    Feb 16, 2020 at 15:50
  • Yes, but I suggest reading the long answers. There may be caveats or helpful tips there.
    – isherwood
    Feb 16, 2020 at 16:02
  • Wow, you put an awful lot of detail into those junction boxes. Is this whole thing wired in EMT metal conduit?? Feb 16, 2020 at 16:46
  • Also, how did a new outlet come to need grounding? Did you use some old 12/2 no-ground that you had lying around? Feb 16, 2020 at 16:47

1 Answer 1


Retrofitting grounds is only allowed on old work. For instance if you have an old circuit where you have already retrofitted ground, and you want to extend a new outlet off of it, you must use 12/2 w/ground cable. Meaning ground is included in the new cable.

Yes, I don't see any problem tapping another circuit for that ground, so long as it's fed out of the same panel and the ground wire is equal or larger than is ordinarily required for this outlet.

If you're just fitting an outlet where a switch or lamp was, then you can do that, provided you have the needed wires available. You can continue using the ground you retrofitted.

  • I am just adding a power outlet to existing wiring I am not extending anything beyond that. Your response in not clear what is the difference between and old circuit that has the ground retrofitted and one (also old that has no retrofitting). In my case I have an existing circuit that has ground (no retrofitting was done) and an old circuit with no grounding and to which I want to add grounding by extending the grounding from the one that has
    – MiniMe
    Feb 16, 2020 at 17:16
  • @MiniMe -- why can't you extend ground from the new circuit to the box you're extending the existing circuit from? Then you can run a W/G cable for your new extension, and be set. Feb 16, 2020 at 17:24
  • That is what I am trying to do here, connect the blue power plug to the ground of the other power plug next to it. They sit on different circuits, both existing, no "new circuit" The only thing that is new is the blue power plug that is being added to the garage door lights circuit
    – MiniMe
    Feb 16, 2020 at 18:09
  • turns out I have a ground wire there i.imgur.com/sSGeS1c.jpg
    – MiniMe
    Feb 20, 2020 at 22:12

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