"Bill" wrote in message news:5560a19a$0$34404

stuff snipped

The risk of what exactly?

Suppose you have a heavy resistive load on leg 1 and a light load
on leg 2 and then suddenly lose the neutral.
What happens to the voltage across the light load on leg 2?
Would 230 volts smoke a small radio on leg 2?

Magic smoke will be forced out of the small radio perhaps even a loud magic
noise, too.
(-:

While a reputable electrician would probably not make this particular
mistake, it's possible for a future modification or rearrangement of
breakers in the panel to inadvertently move one or both individual breakers
(especially in older work) so that they both end up on the same 120V leg of
the panel - which is improper when a shared neutral is involved. If the
split circuit is installed that way, the shared unbalanced load could exceed
the rating of the wire.

Maybe some NEC expert can tell us when the use of a double-pole breaker
became a code requirement for Edison circuits because I know it wasn't
always that way (or that way in 1988). My kitchen had an Edison circuit
*without* a tied breaker until I rewired it with separate runs. Without the
tied breakers or a double pole breaker that kills power to both phases, it
is quite possible for someone to be shocked while working on the circuit,
since the neutral wire of the supposedly "dead" circuit could be carrying
current from the sister "live" circuit. DAMHIKT. (-:

There's so little benefit, IMHO, that the risk of using Edison circuits
today doesn't seem worth it. If voltage drop is a problem, use a larger
diameter wire. If you can't afford the extra wire, check the car's seat
cushions for spare change or sell some blood. (-:

Besides, the last time we had this discussion I believe I pointed out that
because "Romex" 12/2 w/G and 14/2 w/G is so widely used, it can often be had
on sale for much less than 12/3 or 14/3 w/G, thus totally negating any real
savings in wire costs.

Same problem with the 2 pole GFCIs needed to protect an Edison circuit. I
can always find a good sale price on the single circuit GFCIs. I don't
recall ever seeing a double pole unit on sale. I do recall when I looked at
2P GFCIs they cost way more than 2 separate 1P GFCIs. I recall paying a
little more than $10 a pop for 20A Leviton GFCIs just a while back when I
ran a new sump pump circuit.

http://www.google.com/search?q=cost+dual+pole+GFCI

The 2P units Google shows are in the $80-$110 range. So it looks like the
Edison circuit is going to end up costing way more than two comparable
single branches, at least if you don't pay list price for your components.

I don't see the tradeoffs being worth it but obviously some people do. For
me it violates the KISS rule.

--
Bobby G.