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View Full Version : 3 Way Switch (Continuity)


hoopplaya4
May 18, 2009, 06:54 PM
Hi All,

I live in the United States and I am trying to troubleshoot a 3-way switch issue. I have two boxes and one light.

In the first box (we can call it Box A), I have no problem finding the "common" wire that comes from the circuit breaker. (I'm using my multimeter).

However, my issue is this: on Box B, I am having difficulty finding the "common" wire that is connected to the load (the light).

Using my multimeter I have bought from Radio Shack, how do I find the continuity? I know how to set it to Continuity mode, but, I am not getting a beep when I touch any of the three wires at Box B. I was under the assumption that to find the common at Box B, it would be the one that "beeps." (I am connecting one needle to the wire, and another to the ground).

Any ideas?

PS The multimeter I'm using is found here:

22-Range Pocket Digital Multimeter - RadioShack.com (http://www.radioshack.com/product/index.jsp?productId=2104114)

stanfortyman
May 18, 2009, 07:17 PM
The grounds would be of no help at all in finding this continuity.

You need to test between two of the three wires from the switch (with the switch removed) and find continuity. Then flip the other switch and try again. The common wire in those two test is your common for the 3-way.

jerro
May 18, 2009, 07:26 PM
On a 3 way switch you have 2 screws on one side and one screw on the other side. The 2 screws across from each other are for the wires that go back to the other 3way switch. The screw that does not have another screw across from it(usually a different color) shoul be your common screw that has the wire that feeds power to the light. You need to set your meter to read voltage not continuity and touch one lead to the common screw and the other lead to your ground wire. Flip switch to see if you have 120volt.

Tev
May 19, 2009, 04:04 PM
Also keep in mind that there may not be a cable in that box that runs to the light. The wire may run back to box A where it is then connected to a cable running to the light.