I have replaced all old outlets with existing wiring (no ground) on 20 amp circuits in 1950 home with new tamper resistant 20 amp decora outlets.

Before doing this I had an electrician trace for placement of GFCI outlets so they are at the front of each run. The boxes are all metal and different from any I have seen (picture attached).

I am wondering if the metal bar in base is some sort of ground or brace?

Additionally, the electrician told me that I should add a copper ground wire from the receptacle ground to the box, so I did. I added the wire to all receptacles including the GFCIs.

All boxes still test as if they have no ground with a plug in tester. All labeled GFCI protected and No Equipment Ground. I just read somewhere that adding the copper wire could electrify the box and then I have read here something that said it is pointless to do but it won't cause any issues.

Can I leave the copper wire connected to all these boxes or do I have to go back and take it out? Is there anything special about these boxes?

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  • 1
    Adding the pigtail won't do anything if the box itself isn't grounded, so no surprise the tester still shows no ground. AFAIK leaving the pigtail won't hurt anything—but you'd still have no ground at those outlets. Do you have breakers, or old school fuses at your panel?
    – Huesmann
    Feb 26, 2023 at 14:49
  • The panel itself is newer - all breakers.
    – Shar
    Feb 26, 2023 at 14:55
  • Perhaps you could just throw a GFCI breaker on the circuit(s) in question and be done with it. Maybe one of the sparkies will confirm whether that works or not.
    – Huesmann
    Feb 26, 2023 at 14:58
  • 4
    The "metal bar" appears most likely to be a nail going through the box to secure it to the stud.
    – Ecnerwal
    Feb 26, 2023 at 15:19

1 Answer 1


IMHO, pointless but certainly no harm. Except that it is not pointless if it is required by code. The usual rule is "receptacles must be grounded to metal box". If the rule is actually "receptacles must be grounded to metal box unless there is no system ground connected to the box then the wire would not be needed - but it still wouldn't hurt.

Assuming that "receptacles must be grounded to metal box whether or not there is a system ground" then I think the electrician is correct. Specifically, a high-quality receptacle ("spec. grade", "self grounding", and that should include any GFCI/receptacle) does not require a grounding wire. However, based on the picture this box is covered with paint, drywall mud, etc. Which means that the grounding via the yoke may not be any good, so connecting a wire from the ground screw on the receptacle to a screw in the metal box makes sense.

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