Girlfriend changed light switches, lights flashed and now the lights won't turn on

Question

Okay, so pretty simple. She replaced two 3 way switches and a 4 way switch. The switch was flipped and the lights turned on and then went out immediately and now won't come back on (there was a loose connection in one of the switches).

The circuit is our hallway and bathroom. The light switches were 3 hall switches. The bathroom light fixture still works and all of the outlets still work (bathroom and hallway).

I will highlight what I have done so far as I am out of ideas.

I disconnected all of the switches and wired them as they should be. I validated this by using a multimeter and noncontact volt meter. I checked all the outlets and switches in the hall and they are all getting ~120v on the multimeter. The switches are working as they should (tested resistance and continuity). I decided I would check the sockets next. With the switches off, I am getting some phantom voltage it seems but when I turn on the switch, I am getting around 15v only. Here is where it gets interesting. If I take the red prong from multimeter and touch the center of the socket and change my ground (using threads of socket when getting 15v) to the metal canister in the ceiling (recessed lights) I get ~120 v. I also tried using the ground from the light switch when testing the socket and get ~120v. So it seems that perhaps something happened to the ground wire used for the lights? The ground wire going to the switches is good. I would love some ideas on what to do next as I am totally lost.

I have (2) 3 way switches and a way switch. There are 5 lights hooked up to these switches and none of them work. Like I said, the outlets still work and bathroom lights still work as well (all on same circuit).

Thank you for any help you can provide.

Answer 1

Hmm, you don't even know white is neutral and that grounds are important, so you should recognize that you have a rather enormous "skill gap" here.

Now, here is one of the approximately eight ways that a 3/4/3 way circuit can be arranged.

You haven't been specific about where your friend went wrong initially wiring the 3/4-way switches, but the usual problem is moving the wires to the same physical position on the new switch (because they don't know what else to do). Actually the terminal locations are highly randomized from switch to switch - even the same model (economies of manufacture may favor making switches mirror imaged). You must rely on the markings or screw colors - but of course for markings to work you must know what the words mean, hence back 'round to skill.

But this is the arrangement you're after. While the switches will have that exact specific relationship, power could be injected anywhere, and the lamp could be positioned anywhere (including to the left of the first switch at the power supply, with only black + red going to the first switch!) And lastly, just to make things challenging, the colors aren't simple or indicative like this.