RBM wrote:
"jack" wrote in message
news
I want to add a circuit to a 208 panel, but there are no holes and I really
don't want to go at it with a hole saw.

There is a circuit consisting of one outlet connected to the box by 1/2"
conduit. If multiwire circuits are allowed on 208v, I could put the
outlet on one leg of the multiwire circuit and put my new circuit on the
other. That way I can just put my new MC cable to the bottom of the outlet
box, which does have a hole.

Seems to me that it should be pretty much the same as 240v, except that
some current will always be returning over the neutral; but there is no
harm to that. But maybe I am overlooking something (which, given my
knowledge of 208v, is not unlikely)

If I can't use a multiwire circuit, can I simply attach the MC cable to
the bottom of the outlet box and run it up through the conduit to the
panel box? I think 1/2" will take 6 #12 wires.

That works. Normally you would add 2 wires to the conduit and splice to
MC at the outlet box. In both cases the outlet box needs to be big enough.

You have 4 conductors in the conduit. The wire ampacity has to be
derated to 80% (4-6 wires). If you are using #12 THHN the ampacity is
30A which derates to 24A (and can only be used at 20A).


What you're proposing is fine. Bring your cable into the outlet box, splice
the two neutral wires together with a pigtail to the outlet, as the neutrals
of a multiwire circuit cannot be dependent upon a device, and run your new
hot leg for the new circuit to a circuit breaker adjacent to the one feeding
the outlet circuit

I agree except the 2008 NEC wants a common disconnect on multiwire
branch circuits (210.4). Could be a breaker handle tie. (The change
should make multiwires much less attractive.)

--
bud--