David said:
Interesting.. I live in a small 2 level townhouse. There are 3 breakers
(switches) labeled "lighting" in the breaker panel. One of those breakers
controls the downstairs lighting, and the other 2 control the upstairs
lighting. There are other breakers in the breaker panel labeled range, A/C,
water, dryer, etc., and one labeled "main" that shuts everything off. I
tested all of the upstairs receptacle and switches that are controlled by
the same breaker as the GFCI receptacle. They all tested normal. Could a
problem with a receptacle/switch controlled by one breaker cause a problem
with a receptacle/switch controlled by another breaker?
The following answer is in response to your question. It is not
related to your problem, which right now boils down to not
knowing where the capped wires go. Ok, setting that problem
aside....
Ignoring bizaare events and wiring errors, there is a way for
that to happen, if you have shared neutral circuits.
If the neutral wire opens on a multiwire (shared neutral) circuit,
then the breaker on one circuit can affect the equipment on the
other circuit. The open neutral causes the two circuits to be
in series. I'll try to draw a diagram of a shared neutral circuit:
hot1----------equipment--+
neutral--------------------+
hot2----------eguipment--+
In the above, the current can flow from the hot, through
the equipment back to the panel via the neutral. (The +
signs indicate that everything is connected together.)
There is an open in the neutral in the diagram below:
hot1----------equipment--+
neutral-------open ------+
hot2----------eguipment--+
In this diagram, current cannot flow from the hot, through
the equipment and back to the panel via the neutral. But it
can flow through the equipment connected to the other
hot. The effect is that the two pieces of equipment are in
series, and the circuit breaker for either hot leg will
affect both pieces of equipment.
Ed