Re: Neutral wire at switches for outlets?

[Ian Shef <invalid@xxxxxxxxxxxxx>]

"E. Lee Dickinson" <lee@xxxxxxxxxxxxxxxxxxxxx> wrote in
news:ddi7pn$jo3$1@xxxxxxxxxxxxxxxxx:

>
> "Ben" <galanti@xxxxxxxxxxxxxxxxxxx> wrote:
>
>>I know this is a stupid question, but is there any reason why switches
>> for outlets can't have neutral wires?
>
> I have a somewhat related question:
>
> In my home, there is a 3-way circuit which controls a group of outlets
> and a group of lights.  In the process of stripping the outlets out of
> the circuit,  I discovered that the circuit hot comes from the breaker,
> but the neutral comes from another (unswitched) circuit of outlets.
>
> By my thinking -- the neutrals are all common at the breaker anyway, so
> it shouldn't make a difference. Is there any reason for me to be
> concerned about this?
>
>
Answer:  It depends.

I believe that this is permitted in the U.S.A. as long as:
1)  The two circuits are on opposite phases of a split phase service.
2)  The two circuit breakers have equal limits and are mechanically tied
together so that tripping or turning off one breaker shuts off both.

Rule 1 is important because two circuits sharing a neutral on the same
phase could potentially double the current in the wire.  Being on opposite
phases, the current is the difference between what the two circuits are
using (leaving out reactive loads).

Rule 2 is important because it prevents shocks during servicing.
Otherwise, with one circuit shut off, the other circuit can make the
neutral hot through any lights or appliances that are left on.  I have been
shocked (*) by such a circuit that did not have tied breakers because it
was wired before this rule was made part of the NEC.

(*) I was shaken and greatly surprised but learned a valuable lesson:  Use
a meter to verify prior to touching!

In the cases that I have seen, the wiring from the circuit breaker panel to
the loads used Romex with four wires in this case:  Ground (bare), Neutral
(white), Line 1 (black), Line 2 (red).

Other countries may be different.  Particular locations within the U.S.A.
may be different.  Older wiring may be different.  Mistakes can cause
differences.


--
Ian Shef     805/F6      *    These are my personal opinions
Raytheon Company         *    and not those of my employer.
PO Box 11337             *
Tucson, AZ 85734-1337    *