While I had my 3 way switches open, I used a DMM to figure out what was hot and cold while flipping the switches. While my traveler shorted with the line feed showed 120VAC as expected, at least one traveler line (I think it was whichever one in "open" state) showed 17VAC. I expected the traveler to be closer to 0VAC.

Is this indicative of a hardware failure, or is that normal?


It's capacitively picking up some stray voltage from the hot wire that parallels it. Your DMM has a high-impedance input so there is no place for that induced voltage to go. If you were to place a load on the wire, the voltage would go to near 0V as you would expect.

Bottom line: It's normal and this is a case where the sensitivity of the instrument you're using (i.e. the DMM) is fooling you.

  • 1
    Some DMMs have a "Low-Z" switch position. The lower input impedance pulls the phantom voltage reading down to zero where it belongs. – John Canon Dec 26 '19 at 4:04

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