Using a 3 way switch used instead of single pole.. oops.

kbucci

First of all I know it was wrong. I knew I had a ground wire and 2 hots, so when I went to the local DIY store I grabbed the first switch that had 3 contacts, figuring one had to be for the ground. Mistake figured out and will be rectified with a single pole switch with a ground connection tomorrow.

The switch worked fine for a while, and I didn't notice something was wrong until every once in awhile when you flicked the switch you would see a spark in the middle of the switch and the breaker would flip. My question is, why was it working most of the time, but tripping the breaker every once in awhile. My guess is maybe when something else down the circuit is drawing power (ie another light is on) it causes the spark and breaker flipping. The problem is fixed, I mainly want to know for my own curiosity.

Thanks

dmxtothemax

If you were using the original switch,
it could have some damage,
a burnt spot on the contacts,
it could be drawing an arc,
then the breaker does what it is supposed to do
it tripps out when it senses an arc !

brric

A grounding conductor terminated on a switch contact?

AllanJ

A 3 way switch will work perfectly well as a "regular" switch with the third terminal (not the dark, or common, terminal) left empty.

Depending on which wire including the ground is put on which terminal of the 3 way switch, the results would vary from a breaker trip every time, to the situation you described, to completely normal operation.

If you get a breaker trip when you flip a switch, some deterioration of the switch has taken place. After you correct the problem, the switch might last for several more years but you should at least not puzzle over why if it did not.

The more slowly you flip a switch to turn off the light (excluding switches with a built in mechanical snap action) the longer lasting an arc between the opening contacts inside will be. In turn the switch will wear out more quickly. It is possible that the breaker tripping had nothing to do with the ground wire being on one terminal. A breaker with an arc fault circuit interrupter inside may trip with an ordinary light turn off where you moved the switch toggle too slowly.

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