Doug Miller wrote:
In article , "Percival P. Cassidy" wrote:
On 06/06/07 08:05 am Doug Miller wrote:

Our house has 3-conductor wiring for the range and dryer. Would it be OK
according to the NEC to run an additional (green) conductor alongside
the existing wiring and replace the receptacles by 4-pin ones? If so,
what gauge? Or would the existing wiring have to be replaced?
Yes it would be OK,
No, it's not. All conductors for a circuit are required to be in the same
raceway or cable. [2005 NEC, Article 300.5(I)]

305-I is underground (buried). You want 300.3-B.


Except for a few feet of EMT where the wiring for the dryer outlet come
down the wall* (and I could easily get a new ground wire in at the top
end to connect to a 4-pin outlet), there are no raceways: the existing
wiring comes out of the panel (which is surface mounted, so I could
easily run the ground wires out through the same knockout/clamp) and is
stapled to the underside of the joists.

Doesn't matter, it still doesn't meet Code. Note the word "cable" in the part
I cited. It absolutely is a Code violation to run another conductor
of the same circuit alongside the existing cable.

There is an exception in 300.3-B. Separate grounding conductors can be
run for receptacles on existing ungrounded circuits (or extensions of
existing ungrounded circuits), connected as in 250.130-C.


Moreover, the NEC no longer permits the use of uninsulated neutrals, which is
what you have in the existing cable. It met Code at the time it was installed,
but if you modify the circuit, you're required to bring it up to *current*
Code -- and that requires the neutral to be insulated. You can't achieve that
with the cable you have now.

I agree that the uninsulated neutral is a fatal problem, so to speak.

*And it's just occurred to me that running Romex in conduit probably
wasn't kosher either. I wasn't the one who did it.

Despite repeated posts in this ng from certain individuals who claim that Code
doesn't permit Romex (technically, NM cable) in conduit, it's actually
perfectly fine for above-ground installations.

It is a common practice to run Romex down a wall in EMT to protect it.


but it's not necessary.
That's true. Code permits connecting new appliances to *existing* 3-wire
circuits, but prohibits installing *new* 3-wire circuits for this purpose.

If it were me, though, and it wasn't too much effort or expense, I'd pull new
4-wire cable.

That's what I'm trying to decide. Each run is approx. 15ft. What gauge
should be used? -- either for a separate ground wire or for whole new
wiring runs.

Gauge depends on amperage. For 30A, you need 10-ga copper; for 40A or 50A,
8-ga.


Grounding conductors are sized from 250.122. #10 is OK for up to a 60A
circuit.

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