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Rich Wales wrote:
> My mother's house was built in the early 1950's. Most of the
> electrical outlets are the original, two-prong outlets, though
> a handful were replaced at some time(s) in the past by newer,
> three-prong outlets.
>
> I was checking the newer outlets recently with one of those
> testers with three neon bulbs that light up in various combi-
> nations depending on the circuit status, and most of the new
> outlets were showing an "open ground".
>
> I shut off power to one circuit and opened up the electrical
> box containing one of these outlets to have a look, and I was
> dismayed to discover that the ground screw on the outlet was
> not connected to anything at all! However, even after I had
> attached a ground wire to the box and to the ground screw on
> the outlet, it didn't make any difference -- the tester still
> showed an open ground.
>
> My tentative conclusion, at this point, is that the boxes are
> probably not grounded. Again, we're talking about early 50's
> construction, so I assume grounding of electrical boxes was
> simply not a standard practice required by the code when the
> house was originally built.
>
> Is it reasonable for me to conclude, at this point, that the
> only safe way to get these outlets properly grounded would be
> for an electrician to ground the electrical boxes?
>
> This is a one-storey, ranch-style house in California with a
> crawl space under the house (no basement). In general, should
> I expect it to be possible for an electrician to do this job
> by connecting a ground wire to each box, then routing all the
> ground wires through the floor and grounding them all? Or is
> the job likely to be more complicated than that?
>
> Rich Wales richw@richw.org http://www.richw.org
>
Yes, you're correct that box grounding wasn't required
in the 50's (with some exceptions).
Yes, new equip ground wires *could* be run as you imagined,
though there are technical issues with mechanical protection.
They would run to an euip ground in the service disconnect .
2 questions come to my mind:
This will be an onerous task, drilling up/down to each box
and working in the crawl space. Is it reasonable to expect
to find an electrician willing or having the time (where you live)?
What appliances will you be using that have some compelling
need to be grounded in those rooms?
If you're concerned with shock hazard from touching some
appliance, would a GFC recept protect as well?
They can be retrofitted even where the box isn't grounded.
Jim
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Re: Grounding the receptacle boxes in an old house
