4 way switch trouble shooting


Old 12-06-13, 03:59 PM
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4 way switch trouble shooting

Good afternoon all!!!

I have a 4 way switch controlling 3 lights that was working not too long ago, but now functions very oddly. There are 3 switches (obviously) one on the 1,2, and 3 floor. The switch on the 3rd floor is the 4way. When the 4 way switch is up none of the lights work and when down it will either turn on 1(3rd floor light) or 2 (1&2 floor lights) lights on depending on the other 2 switches. I did all light switch configurations and these are my results

1 2 3 (floor)
u u u off
d d u off
u d u off
d u d off
u u d 1&2
d d d 1&2
u d d 3
d u d 3

I am assuming that the 4 way is broken some how, but can't figure it out
Any help would be greatly appreciated!
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Old 12-06-13, 04:17 PM
Tolyn Ironhand's Avatar
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Welcome to the forums!

If you (or somebody else) have not made any changes to the switches you likely have a bad switch. It could be either the 3 ways or the four way switch. Switch position means nothing. However, looking at your list you have "dud" twice and you have no "duu". I suspect since the lights do not work with switch #3 in the up position, that is where your bad switch/wiring is located.

Best thing to do is to remove the switches from the circuit, carefully writing down what wire goes where, and test them with an electrical meter. If you do not have a meter, this would be a good time to invest in one. A cheap analog meter is only about $10. If you must have a digital meter, expect to pay over $100 for a good one that is not effected by phantom voltage.
Old 12-06-13, 04:21 PM
ray2047's Avatar
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Location: USA
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Open the 4-way and check the connections are tight. If nothing out of place mark which wires went to the brass terminals and which went to the black terminals. Do not disconnect the two wires connected only to each other. Replace the 4-way switch. If that doesn't help time to replace the 3-ways marking the common before replacing each switch.
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