Recently, I was replacing a light fixture in my home. When I
attempted to cut the breaker to that fixture, I discovered that I had
to turn off two breakers to kill the circuit that includes the light
fixture. My assumption then, is that the two circuits (one for each
breaker) that should be separate have somehow been crossed together
such that they both breakers effectively power a single circuit.
I'd like to fix the problem. Is there a simple way to determine where
the two circuits have been connected?
I wish there was. It would save me a lot of time trying to find the
interconnection. I find this situation occasionally in older houses that
have had wiring changes done by homeowners and handymen. It is not uncommon
to see this in homes with knob and tube wiring that has been refed with a
new circuit. Start at the circuit breaker panel and physically follow the
respective cables as they make their way through the house. This is a time
consuming task. When you encounter a junction box disconnect the feed from
the circuit breaker panel and see if it is still hot. If so then trace the
wires from that junction box and so on. In the box containing the wiring
for the light fixture that you just changed was there a considerable number
of wires there? That might be a clue. You should also open all outlets,
switches, and light fixtures on this circuit and separate the conductors to
see if you have two hots.
On Mon, 27 Oct 2008 11:52:30 -0700 (PDT), drhender
There is not an easy way, but there is a straight forward way.
Identify all the devices on the two breakers. May as well start with
the lamp you are working on. It should have an in and out. When you
break it at that point, half of the stuff should go out with one
You should work it back until you get to the point where the two are
If you want to save yourself a headache, you should take a picture of
the box before you break any taps.
There are two approaches as I see it:
1. Follow the wiring and split it somewhere in the middle, as others
2. Pick one breaker, disconnect it, and remove the wiring back to the
first junction box. An alternate to removing the wire, re-route it to
a box and install a plug so you don't have a bare live wire dangling.
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