Electrical Wiring in the Home/3 way switches


Hello Bob,

At home there's a 3-way switch in the stairs, so the light can be turned on/off from the switch in the ground floor and also from the switch in the first floor.

Without us doing anythig, it stopped working correctly. Now it happens that... from the ground floor, the switch works normally, the light can be turned on and off by flipping the switch. But from the first floor, it's possible to turn the light on and off only if the light has previously been turned on using the ground floor switch.

Once the ground floor switch is turned off, we can flip the first floor switch back and forth all we want, but nothing happens to the light, it doesn't turn on.

As nobody has changed anything in the electrical system, what do you think could be causing this?

Best regards, and thank you in advance,


Normally I would say it was wired wrong.  But if nothing changed, then either one of the switches is bad, or the wiring came loose.  Most likely the ground floor switch is bad. But you might want to replace both of them while you are at it.  If you replace the switches, any loose wires would probably be fixed also.
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Electrical Wiring in the Home

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Bob Sponaugle


Just about any home wiring question. (not appliance repair) I have done all kinds of home wiring for myself, including adding a new breaker box, etc. Please, questions from North America only. Please be specific with details.

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