In article , "gorehound" wrote:

The reason I asked when they started allowing it again is because my
instructor said that code says you are supposed to use a double pole breaker
when sharing a neutral.

Either:
a) your instructor is incorrect;
b) you misunderstood; or
c) your instructor is a Canadian. (AFAIK, this *is* required under the CEC.)

I work for an electrician and we were wiring up a
portable gfci board for the local chili cook off and if we used separate
neutrals the pull through the carflex would have been more of a pain than it
was. I asked about the double pole and he said they said it was fine then
they said it wasn't then they said it was again.

The double-pole breaker is required under the NEC if the circuit supplies
multiple devices on a single yoke, or supplies both line-to-neutral and
line-to-line loads. It is not required under other circumstances. [2005 NEC,
Article 210.4]

What makes me nervous about
the practice is when you are working on something and you shut the breaker
off you think ok I'm good to go.

Makes me damn nervous too. My current house had three such circuits, all
unidentified, all on separate single-pole breakers. All Code-compliant and
perfectly legal, too, and I had no idea the circuits were sharing neutrals
until I happened to pull off the panel cover and see the red wires.

They're all on double-pole breakers now.

Now you go and pull down the light fixture
and start disconnecting it and get knocked on your ass because the neutral
is shared with the refrigerator circuit. If the 2 circuits were on a double
pull breaker the neutral wouldn't be carrying the load from the refrigerator
because both circuits would be dead.
Any thoughts?

IMO a double-pole breaker should *always* be used on shared-neutral circuits
(aka multiwire branch circuits or Edison circuits), even when the NEC does
*not* require it, for exactly the reason you cite. It is IMO a foolish and
false economy to not spend the extra ten dollars on a proper double-pole
breaker, when failing to do so may cost a human life.


--
Regards,
Doug Miller (alphageek at milmac dot com)

It's time to throw all their damned tea in the harbor again.