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I'm installing a new 4-way switch.

When I flip any of the switches, it's not toggling the on/off state of the final hot wire. The final hot wire (which will supply the light) is always hot. All the travelers are always hot.

Something is supplying continuous power. I'm not sure what I did wrong. I checked these things:

  • I tested each switch, they're not faulty and are all showing correct continuity.
  • I checked the neutrals and the grounds, they're not hot.
  • I turned off all other circuits in the house, it's not accidentally connected to another circuit.

Any ideas?

I wired it like this:

4-way switch wiring diagram

Here are some photos of the actual wiring:

Switch 1 -- the three-way switch is on the left, the other is a single-pole switch supplying another light. They're both connected to the supply power.

Switch 1 -- the three-way switch is on the left, the other is a single-pole switch supplying another light.

Switch 2 -- 4-way switch enter image description here enter image description here enter image description here

Switch 3 -- last 3-way switch (connected to light) enter image description here enter image description here

  • You think you wired it like the diagram. But something, somewhere, is different. Which happens to the best of us. Please upload pictures of the wires going into each switch. Try to focus the pictures (or make two of each box - switch & back of box) so that we can see how the cables are arranged. – manassehkatz-Moving 2 Codidact Aug 13 at 14:40
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    One thing to know is that the screws aren't always in the same position across brands. Be sure you know how to identify them by function. – isherwood Aug 13 at 14:41
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    @manassehkatz-Moving2Codidact I added the photos. – Sarah Aug 13 at 15:30
  • @isherwood I can identify the common screws, but I might have missed something about matching up the different travelers. I've got the supply power correctly wired to the first black screw, and the output power correctly wired to the final black screw. For the travelers, I wired the travelers to "either" brass screw of switch 1. For switch 2, I put the inputs on "either' side of the input screws (the two top) and the outputs on "either" side of the output screws (the two bottom). For switch 3, I wired the travelers to "either" brass again. Could the travelers be mis-wired? – Sarah Aug 13 at 15:32
  • Is this circuit on a 15A or 20A breaker? – Harper - Reinstate Monica Aug 13 at 19:29
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It was this: https://diy.stackexchange.com/a/10982/38476

I was testing it without a load on it, and once I put a light fixture and bulb it behaved normally. It’s common for 3-way switches to have phantom voltage when there’s no load.

| improve this answer | |
  • It should not be common for any "regular" switches to leak voltage when there is no load. But depending on the type of switches and what/how you are measuring: (a) some smart/dimmer/motion/timer/etc. switches do leak current, deliberately, but then generally needing at least one bulb/fixture installed to do so (and are otherwise non-functional) and (b) there is often "phantom voltage" with wires on circuits that are off. Actually, now I see your link is really about the phantom voltage - but that is not a "leak", it is a different type of thing (and not a problem except confusion). – manassehkatz-Moving 2 Codidact Aug 14 at 2:17
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    It's not the switches that leak, by the way. What you're seeing here is due to phantom voltage due to capacitive coupling (leakage, if you will) between the two traveller wires in each cable. (When a 3-way is OFF, one of the travelers is connected to the source, while the other is connected to the load.) – ThreePhaseEel Aug 14 at 2:59

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