I replaced an old light fixture over my kitchen sink with an LED light. Everything worked well. The switch beside the sink with a standard outlet in same box were old ( at least 40 years) also. I decided to replace the switch and put in a GFI outlet. 5 years ago had my fuses replaced by an electrician with a complete new breaker box. The breakers are mislabeled some I am not sure what they are supposed to say.
I located the breaker for the switch. It was off--no power to switch but the outlet was still live. Found that breaker shut it off. I took off the switch plate and to my amazement was a mass of wires. I carefully unraveled everything cleaned out the plaster from inside the box which is not attached to a 2x4. I reattached the wires as they had them to the new switch and outlet went to reset breakers the switch breaker reset the outlet would not. I already figured the GFI wouldn’t work until I figured out what all the wires were going to. I took out the GFI and put in a new standard outlet just to close it up until I could check what was on each breaker. I had flipped the breakers on so my main kitchen light would work. With better light I could see the light switch needed to go in more to put the plate on. As I barely touched the switch I heard the dreaded crack then darkness. I assumed I just shorted out the switch before I touched anything else I went to check both breakers were off. To my surprise 3 breakers were tripped. When examining my light switch and outlet it appears the ground wire touched the lower pole of the light switch.
I have tried replacing light switch and outlet with new still 3 breakers tripped here is a list of everything I have tried and still 3 breakers tripped.
- Disconnected and capped all wires in box
- Checked every switch and outlet involved in my house and garage to see if I could visualize and damages or issues that May trip a breaker.
- I disconnected new light fixture the switch went to.
- I looked in garage and basement to see if I could see anything suspicious with wires.
The switches and outlets that are involved are kind of random not in one location or group with others that are working in between. Could I possibly shorted out three separate breakers 2 x 15 amp. 1 x 20 amp. Also to note there are 4 sets of wires in box (1) RBW. (3) BW ground on all. I can give more details on wiring and what I have tried there if needed.



I'm in a similar situation where I want to install GFCIs around the kitchen sink but I backed off when I realized there was more than 1 breaker involved. Here is some helpful reading while someone more knowledgeable than me helps you:
– eszed Jan 28 '24 at 11:51https://diy.stackexchange.com/questions/153510/installing-gfci-outlets-in-multiwire-branch-circuit
https://diy.stackexchange.com/questions/71652/what-is-a-multiwire-branch-circuit