On 9/16/2011 6:43 PM, Andy wrote:
On Sep 16, 6:15 am, Doug
wrote:

Also, someone working on one circuit and not knowing that the neutral
carries current from a different circuit could receive a fatal shock
from that neutral -- how would he know to shut down both circuits?

Andy comments:
I am confused as to how you think someone could receive a shock
from the "neutral" wire...

Because it carries current. The same current that's in the hot.

It is normally not disconnected in any
configuration ---

It doesn't really matter whether it's disconnected or not. It's carrying
current.

Consider two simple circuits, A and B, each supplying no loads other
than a single 100W light bulb, each of which is turned on -- but,
unbeknowst to you, their neutrals are cross-connected. Well and good.
Now suppose you need to replace the fixture on circuit A. Knowing that
it's on circuit A, you shut off that breaker, and disconnect the hot
lead to the fixture. Now when you go to disconnect the neutral lead, you
get a shock, because -- and I think this is the point you are missing --
electricity doesn't "follow the path of least resistance" as many people
believe, it follows *all possible paths*, including the one that you've
just made with your body by touching that energized lead.