No power to switch box and overhead fans/lights in master bed/bath. No tripped GFCI, no tripped breakers

Question

Just moved into a 2-story home built in 2002. Upon move in, all lights and switches worked except for a pantry light downstairs and one of the outlets in an outlet box in a small bedroom upstairs.

Things I did:

1. Opened up the switch box for the broken pantry light to find that it had cracked in half. Went to HomeDepot, got a replacement switch, and replaced it. Only involved moving the ground, incoming hot, and outgoing hot lines from one switch to the new one. Now the light works.
2. Opened up the outlet in the small bedroom to find that everything looked okay. Didn't move any wires, just reinstalled back into wall after inspection. Then I opened up the switch box in this room that controlled the outlet that wasn't working, to find it also was cracked in half. Same procedure as above: got a replacement switch, moved the ground, incoming hot, outgoing hot wires, and reinstalled. Now the outlet works.

At this time, a comcast installer came and spent some time playing with stuff to get the internet coax working. I did not see everything he did.

Later, I realized the overhead lights/fans in the master bed and bath no longer work. They did previously work before the 2 switches were replaced and the comcast install occurred. All of the outlets in the master bed+bath still work. Checked all breakers, none were tripped but I reset them anyway. I could find only 4 GFCI outlets (all located downstairs), and none were tripped but I reset them all anyway. Opened the switch box in the master bed to find no power for any wires coming into the box.

It seems like there's only one breaker for the outlets and overhead lights/fans in the master bed/bath. How is it the outlets can still work but the overhead lights/fans do not?

Answer 1

Quite often a home will only have 1 circuit to a zone or room it is quite common to tap the outlets for the lights I usually find this when both hot and neutral come into the box then go up to the light. If this is the case you probably have a bad splice / junction somewhere and it is very common for that to be at a receptacle that has backstabs. It is also possible for a loose wire in a wire nut or broken wire these are the main failures I find after verification it is not GFCI protected some place weird like a closet.

I work back to the breaker box. If I followed you everything now works except this light / fan. The tough part will be figuring where the wire comes from, you may try turning the circuit off and see what outlets may also go out the one in the small room? There could be a bad connection in that box. If you tested with a non contact volt meter and had no power it is usually the hot that is open. If you pull the switch you may be able to see that the feed comes from the bottom going out the top.

Imagine where the wire goes don’t forget to check the other side of the wall if there is a common wall and start working towards the breaker box. Some electricians have through wall scanners these are two expensive for most home owners but a stud finder with a wire alert can be helpful turn everything else off in the area and trace that live wire through the wall if it stops check the other side for a switch box or receptacle but that’s how I find an open circuit when I don’t have a clue where it goes.

Remember electricians are cheap we don’t like to waste wire it is expensive. So we may pick up an outlet in the hall or a light at the stairs and this device could be working just the hot or possibly neutral has a bad outgoing connection from that point. My guess would be the receptacle closest to the switch.

Answer 2

Except for certain code-required dedicated circuits (mostly kitchen, bathroom, laundry), you can have a lot of stuff on one circuit. That is especially true these days with LED lights, but even in the old days. 1/2 my house - lights in 2 bedrooms, receptacles in 1 bedroom, lights and cooktop exhaust fan in the kitchen, several receptacles and some of the lights in the basement - are all on 1 15A circuit!

When only one part of it goes bad, the problem is either in the first part that is bad or the last part that is good. You have determined the switch is OK because you have no power on the wires. So you have to trace it backwards to figure out where it came from. You likely have a loose wire, open wire, bad receptacle or bad switch. Check especially for any "back stab" connections.

What caused it? You might figure out when you find the problem. But since you already had 2 broken switches, I wouldn't be surprised if you find more things broken or about to break. It is quite possible that when you or Comcast was doing some work, you pushed something "over the edge".

Answer 3

If you are still at a loss I would get a volt meter and check the voltages at the outlets and switches including ground to hot and neutral. Next I would install an ark fault if you can not figure it out. I would check the wire nuts especially the ones with several wires.