Wiring Help


Old 09-26-05, 12:45 AM
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Wiring Help

I don't know whether anyone can help me - We have a light that is controlled by two switches (one either end of the hall) One of these switches has two switches as it also controls another light.

Every combination of wiring we have tried has ended up with either one switch operating both lights, or no switches working, or only one switch working!!!!! - HELP please!!!!
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Old 09-26-05, 05:20 AM
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Old 09-26-05, 05:35 AM
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The safest way to replace two three way switches is to replace one at a time, verifying proper operation after each switch is replaced. They key is to NOT move wires by position on the switch, but rather by function.

A three way switch has one common screw and two traveler screws. The common screw is a different colr than the traveler screws. Those screws could be any color except green, so don;t get bogged down by color.

Yo are apparently beyond that stage, so we must move on.

Now you must either wire by trial and error, or by utilizing tools to make the job easier.

Trial and error. There are 6 ways to connect the three wires to the three screw terminals. Three of those 6 ways are electrically equivalent. Just try each wire on the common screw and the other two on the travelers. Try each of those three conbinations with the same combinations at the other switch. Eventually you will find the combination that works. There are only nine that you have to try. You can speed up this process if you can identify the common wire at one switch or the other switch. This is usually possible.

Testing and inspection. This method involves understanding how a three way circuit works and making tests on the wires while they are live. You must apply power to the circuit and use a tester to determine where power enters the circuit, and then determine the common wire from there. This method is trickier if there is no ground in the circuit (older wiring) and if there is no neutral wire (switch loop).

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