=> Not so. In this style of wiring, the neutral carries the difference in
=> load between the two hot phases, not the sum. (It's in the Canadian
=> Electrical Code to wire kitchens similarly to this - with "split
=> duplex" outlets, where the top outlet is fed by one phase and the
=> bottom by the other, but the neutral is shared.) There are a couple of
=> trick, most important being to wire the outlets so removing a single
=> outlet from service doesn't interrupt the neutral to the rest.
The thing about this that I don't understand is that when I wired my
new home a while back the code didn't demand much of this technique.
No documentation in the panel describing which circuits were wired in
this manner. No requirement that the breakers even be side by side.
Someone making a change in the panel wiring could easily put both hots
on the same phase and now you do have a hazard. An innocent mistake
could start a fire.
=> The reason I want to do it is to avoid running the extra neutral - I'm
=> planning to use pre-stuffed BX for the workshop, and 12/3 is just
=> the right thing.
And another reason is that 12/3 is round, (not flat) and *much* easier
to pull thru the studs. Unfortunately, it costs twice as much per foot
(but it has only has 33% more copper).
BTW, the $100 cost is probably right on. 6 years ago I priced one for a
heater installation near a whirlpool tub - $85 for a 20 amp.
John Miller
<johnm@ims.com>
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