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Although many of the original two-prong outlets in a rental property (built around 1958) have been replaced with three-prong ones almost none of them are actually grounded (the couple that are grounded appear to be in a non-original addition to the property), as our outlet tester indicated an open ground on these outlets. We would like to plug electronics like TVs, game consoles, etc. into some of these outlets. I understand there to be a risk of ESD damage to the device if we were to plug in the electronics into the outlet as is, in addition to the increased risk of electrical shock by a metallic malfunctioning device.

So what kind of DIY solutions do we have to choose from, and in what order of preference should we opt for one solution over another? Since this is a rental, we would like to stay away from expensive solutions like tearing down walls or having the entire house re-wired.

Possible solutions I've seen suggested: (apparently some of these solutions may or may not be good ideas?)

  • Check for unused grounding wire, and connect if found (great option, but I suspect we will not find such wiring based on the age of the building)
  • Replace receptacle with ungrounded GFCI outlet
  • Connect a ground wire from the outlet plug to it's box (presuming we discover the box is metal not plastic) and use the box for ground
  • Ignore the lack of proper ground and cross our fingers none of our electronics get damaged
  • Run an extension cord from a properly grounded outlet in a non-original part of the house to where the electronics will be?
  • Something else?
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1 Answer

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  • Check for unused grounding wire, and connect if found (great option, but I suspect we will not find such wiring based on the age of the building)

This is the only option that will actually provide equipment grounding, assuming you find an equipment grounding conductor in the box.

  • Replace receptacle with ungrounded GFCI outlet

While this will provide ground-fault protection; which is good, it will not provide equipment grounding. In fact, when you do this you have to add a label that reads "No Equipment Ground" on each receptacle protected by the GFCI.

  • Connect a ground wire from the outlet plug to it's box (presuming we discover the box is metal not plastic) and use the box for ground

This only works if the metal box is connected to an equipment grounding conductor, otherwise it offers no grounding at all.

  • Ignore the lack of proper ground and cross our fingers none of our electronics get damaged

This is probably the most common solution. Though most people aren't ignoring the lack of grounding, they simply don't know they need it.

  • Run an extension cord from a properly grounded outlet in a non-original part of the house to where the electronics will be?

This is a temporary solution, but you'd have to protect the cords from damage and use the proper size cord.

  • Something else?

There's really not an easy solution here, the only way to do this is to run an equipment grounding conductor.

Other useful questions:

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can you provide the NEC reference for "No Equipment Ground". I was reading it last week but cannot find it again; thought I saw something else like standard 3-prong required it but GFI did not. Also wondering where GFI breaker falls into the mix. –  Jason Jun 15 '13 at 13:31
    
@Monso The answer I provided for this question has that reference. –  Tester101 Jun 16 '13 at 12:10
    
Might it be a "BX" (metal sheathed) installation? If so, does attaching a ground wire to the box (assuming the connections are all tight back to the panel) form an acceptable ground? –  bib Jun 17 '13 at 1:58
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@bib If it's Type MC cable or Type AC cable with a ground strap, then yes the cladding may be able to act as a grounding conductor. However, you still have to insure it's solidly grounded all the way back to the grounding electrode. –  Tester101 Jun 17 '13 at 12:09
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@bib No. That doesn't prove it grounded all the way back to the grounding electrode. Assuming that you don't have a short between your neutral and the cladding anywhere in the branch circuit, no where does the cladding cross a metal water pipe, and what ever panel it comes from is properly grounded then yes it means you have a proper ground. They are most likely safe assumptions but still assumptions. –  Jason Jun 17 '13 at 17:17
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