You may also have a faulty breaker, or the wrong one. Breakers are designed
to handle surges well above nameplate rating without opening just to get
motors started.

Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)

----- Original Message -----
From: "Dwayne Reid" <dwayner@PLANET.EON.NET>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Monday, July 16, 2001 11:24 PM
Subject: Re: [EE]: Bulb Life -- Burned out bulb resurected


> At 10:51 PM 7/16/01 -0400, Robert E. Griffith wrote:
>
> >Wait a minute; maybe I just figured it out.  When there is load on both
> >circuits, if the circuits are 180 degrees out of phase then the current
on
> >the common neutral would tend to cancel - creating a smaller current load
on
> >the neutral wire.  If they were in phase, the current on the neutral
would
> >be the sum of the two circuits so it would have to be rated for the sum
of
> >the two circuits (30-amps).  Is that it?
>
> Got it exactly!
>
> >Here's a somewhat related question.  In my basement, I have a chop saw on
a
> >15-amp circuit that blows occasionally when the saw starts.  If the wire
on
> >this circuit is thick enough, can I replace the 15-amp breaker with a
20-amp
> >breaker?  What gauge is rated for 20-amp?
>
> My first attempt at fixing this would be to pull heavier wire to the saw
> but staying with the 15A breaker.  Here is why:  if the wire is too small,
> the voltage at the saw is too low and the saw takes too long to come up to
> speed.  The breaker will handle surge currents only for a limited amount
of
> time.  Because the saw is still drawing too much current when that time
> limit is up, the breaker trips.
>
> 12 AWG is the standard wire size for 20 Amps.  But in your case, I'd try
> pulling 10AWG wire in.  If the 15A breaker still trips, then go for the
20A
> breaker.  But the heavier wire may just fix the problem.
>
> dwayne
>
>
>
>
> Dwayne Reid   <dwayner@planet.eon.net>
> Trinity Electronics Systems Ltd    Edmonton, AB, CANADA
> (780) 489-3199 voice          (780) 487-6397 fax
>
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