I helped a friend with his 3-way switches today. He has two 3-way
dimmers that used to work to dim one light. He removed the one light
and added six recessed lights, but all should work the same.
Unfortunately now neither of the dimmers work, and each light switch
only functions if the other is in the opposite position (e.g., switch1
only functions if switch2 is down, and switch2 only works if switch1
is up). I followed the following diagram at:
and it is wired accordingly. The only difference is that it is an old
house and there are no ground wires. The switches also aren't labeled
with "common", but it seems obvious that the odd-colored screw is the
common...and besides, it worked before and the only wiring we redid
was at the light (where the power enters as well). Any clues?
First off, you don't install two - 3 way dimmers on the same system, unless
it's a master slave type, which aren't connected like a three way switch.
If you have your switch travelers in one of the lighting boxes, as the
diagram shows, you transposed a common and a traveler.
KIll the power to the circuit, remove the dimmers. With the wires
safely hanging out of their boxes, no shorts, turn the circuit back on
at the breaker panel. Using some sort of test find the wire that has
voltage on it. Turn the circuit off at the breaker panel and connect a
swtch there the hot wire you located goes to the common the other two
are the travelers. switch the breaker ON and check for voltage at the
other switch position. The hot wire here will be a traveler, change
the state of the switch you already installed and check the voltage a
gain at the other switch location. The hot wire should be the other
traveler and the remaining wire will be the common. Install the switch
accordingly. Yes the silver screw is the common, I still always check
using my ohmmeter to make sure. Make sure the dimmer will handle the
total wattage of the lamps.
Some dimmers must work with a switch on the other side. The ones in my
house are like that. Once you get things working with the switches
again install a dimmer. Let a couple of people review my instructions,
sometimes I dont alway write what Im thinking.
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