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zxcvbob zxcvbob is offline
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Default house wired without separate ground - problem?

Nate Nagel wrote:
zxcvbob wrote:
Nate Nagel wrote:

Bob F wrote:

"Nate Nagel" wrote in message
...

All right, I'm feeling mildly dumb and a little sheepish not to
mention
slightly sick here... just bought a house for the first time less
than
a month ago, and knew that it had some minor wiring "issues" but now
that I'm assessing what I have it appears that there are bigger issues
than previously anticipated. Anyway, here's the deal. House is a two
story colonial with full basement, built late 1940's.
It appears that throughout the house wherever the wiring was
hidden behind plaster it was run in NM not BX and there is no
grounding,
period.



It's also possible that the wiring could be knob-and-tube in a house of
that age.

Bob


No, it's definitely some early type of NM, although it may not be
officially designated as such. There's two plastic-insulated
conductors (that must be a pretty early use of same; as far as
automotive stuff goes I believe the transition was made about 1955 -
at least it was for Studebaker; I have a '55 coupe which
(fortunately) has plastic insulation on the wiring) in what appears
to be a tar-impregnated cloth jacket. But no ground.

I really, REALLY don't want to have to rewire two complete circuits,
although at this point it kind of looks like I'm going to have to. I
might even have to involve a *gasp* electrician due to the magnitude
of what this project looks like it's shaping up to be, which makes my
Y-chromosome cower in shame. I suppose I could just install new
non-grounded receptacles ahd that would be technically correct,
although then I'm back where I started, as there's computer equipment
on the second floor, and a UPS theoretically should have a ground...
also would feel better if the stuff in the bathroom were grounded
(although I was thinking of rewiring the bathroom anyway to meet
current code with a dedicated circuit, GFCI, etc. which is somewhat
doable as there's a small chase going down to the basement behind the
bathtub, and an access panel, so it's "just" a matter of getting a
cable from behind the bathtub up into the attic and then back down to
the light switch...)

I suppose it's not acceptable to cheat and ground stuff to the
nearest water pipe...

nate




You can still buy ungrounded receptacles and put things back like
original. Most circuits don't really need a ground, like the upstairs
bedroom convenience outlets.

Where you really need grounds (bathroom, kitchen counters near the
sink, your computer UPS, etc,) you can run a separate green wire back
to the service panel ground (or to the nearest grounding electrode
conductor, if that is easier.) The ground wire does not have to run
with the current-carrying wires if you are updating old work.

You can also install a GFCI breaker and then use 3-wire receptacles,
leaving the ground terminal disconnected. In this case, you
technically need to put a sticker that says "GFCI Protected. No
Equipment Ground." on each of the grounding outlets that has a
floating ground.

You can also protect circuits by wiring them thru the LOAD terminals
of a GFCI receptacle.

The most practical solution will probably end up being a mixture of
these methods. HTH :-)

Bob



that may be doable at least upstairs; is it kosher to run, say, THHN
without conduit or greenfield or would I need some kind of plenum rated
wire? Please excuse the dumb questions; I know a lot about fire alarm
but just enough to be dangerous about plain old electrical stuff. Since
I really like this house (and paid enough for it!) I'd like to "do it
right" whenever possible, and certainly would like to be able to say
with a straight face to any prospective buyers in the future that
everything is up to snuff.

nate



From what I can tell, the electric code is silent about that. I just
run a #12 green THHN / THWN-2 wire inside the wall cavities, staple to
the ceiling joists, etc. I run them as neatly as possible and where
they are unlikely to be physically abused. I ground them at a big
split-bolt connector on the main grounding electrode conductor a couple
of feet from where it goes into the electric panel.

I have an older house, and I'm trying to get one properly grounded
duplex outlet in each room, and I don't worry about the ungrounded
convenience outlets. All the basement, bathroom, and utility room
outlets are grounded and GFCI'ed (except the outlet for the freezers.)
All the kitchen outlets are grounded except for one that I couldn't get
a ground wire to so I installed a GFCI receptacle. (the one that I
couldn't ground just happened to be the outlet close to the sink)

Bob