I went to change out a light switch expecting an easy job but I found a mess of spaghetti looking and I don’t know where to start. I’ve attached pictures and am willing to answer all questions. The switches I wish to install are single pole with spots for two wires and the ground. Any help would be appreciated.

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  • Have a look at some standard light wiring diagrams. It's pretty common to have source, a switch loop for each light, and one or more outbound cables for other lights and/or outlets. – isherwood Jan 30 at 14:19
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    A better question would be related to the actual problem. If you're installing smart switches you'll need to connect to the white bundle, otherwise it's a matter of following the existing layout. – isherwood Jan 30 at 14:21
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    This is not the time to get creative. If the old setup works, then wire up your new switches in exactly the same way as the old ones. Do not disconnect anything which you don't need to. The old switch on the right appears to be a "3-way" - so if you don't yet have a new one to match it, don't start the job until you've got one. – brhans Jan 30 at 14:32
  • Both switches work standard ceiling lights. I’m trying to change the switch on the right because the lights get isn’t working (yes, I changed the bulb). I used my voltage detector and have power coming to the switch but no electricity detected at the light fixture. – David Duncan Jan 30 at 14:34
  • Everything I read said it was a 3 way light switch but it’s just a standard 2 way toggle switch. – David Duncan Jan 30 at 14:36

Do they control a light/ceiling fan combo?

The switch on the left is a normal switch and that red wire will go to the fan. That bundle is the feed to the fan/light.

The switch on the right is a 3-way, the black is the switched live to the light. the other 2 wires (red and white) are the travelers to the other switch controlling the light.

You can check this by using a multimeter in continuity mode and check continuity from he black bundle to the white and red of the right hand switch. One line is going to have continuity the other won't. If you flip the other switch which will have continuity will swap. You can then also check continuity between the all the connections of that switch in both positions, which will have the same behavior.

The black bundle would be the live wire. One of those will be going to the same /3 as the travelers I described above.

The 3 way will need to be replaced with another 3-way, otherwise the other switch won't work anymore.

If you don't care about that then you only need to connect from the black bundle to the switch and to the red to the light. and remove and cap off the wires going to the traveler /3

  • Both light switches work two different lights. We recently bought the house and this is how I found it. Both lights were previously working but the light controlled by the switch on the right recently stopped working. I switched the bulb with one I knew worked and it still didn’t work. My voltage detector detects electricity coming in to the light switch but no electricity at the receptacle. I thought maybe the switch went bad. – David Duncan Jan 30 at 14:52
  • Everything I read said the red meant it was a 3 way switch but it’s not a 3 way switch. It’s a typical 2 way, up down toggle switch. – David Duncan Jan 30 at 14:54
  • They used a /3 to control 2 lights then. This is allowed, as long as th white is the neutral you can use other colors for live. A 3way looks just like a 2way by design, however I see 3 wires connected to it, which means it's a 3 way. – ratchet freak Jan 30 at 15:11
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    One from the breaker, one to the lights, one to feed other lights in the rest of the circuit, one to the other switch of the 3way pair. That leaves one more set which is gonna be also feeding other lights. – ratchet freak Jan 30 at 15:20
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    The deciding factor for 3-way switches is 3 separate wire connections beside ground, and 1 black screw and 2 brass screws. Other indicators are the two wires on the brass screws disappear together into the same cable with a third wire also, and lack of "On/Off" labeling on the switch. Wire colors are not reliable, and are especially meaningless in 3-ways. If you can't find any possible location for the other 3way, the last guy may have drywalled over the electrical box, which is a codevio, he should've used a blank cover plate. – Harper Jan 30 at 17:23

A few random points .... Find which breakers give power to which wires and turn them off to remove the switches from the wires. Make sure you write down or sketch which wires are connected to which screws! Straighten out the wires once you are sure they're dead. I use a non-contact voltage tester for this. This makes your life easier and less confusing, no more spaghetti. Generally speaking, bare copper wires don't need to be connected to switches, but do for plugs. Also, you may have too many insulated conductors in that tandem (double) switch box. There is a specified maximum number of wires, switches and wire connectors allowed in any given sized electrical box. You can find box fill calculations online. Is this in a condo? It looks like it. Also, white insulated wires must only be used as the Neutral, unless it is taped with black or red electrical tape at every possible opening to let others know it is HOT, and not just another Neutral.

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