This week I met a problem that’s beyond my understanding. I should preface this story. This is a wiring problem. Wiring is a series of logical pathways. Solving wiring problems, assuming you have a decent understanding of the layout of the system, is the same progression no matter what the problem ends up being. The progression goes something like this: you methodically isolate each segment of the path to determine where the problem lies. You then replace or rewire the problematic item or area following a systematic examination of possible permutations. Wiring is just a logic puzzle. If something is wrong, you can just eliminate possibilities until you’re left with one remaining answer. As Mr. Homes is fond of saying, that answer, no matter how unlikely, must be correct.
Yesterday I was finishing up the wiring for the kitchen. This task involved wiring up the GFCI outlets, some switches, and a light fixture. Everything worked except for one GFCI series. It was one of the two appliance circuits (code requires you have 2 circuits dedicated to just powering your countertop outlets). The confusing part is that my twitter pen (the doda that lights up and beeps if you wave it around a live wire) and my multimeter were showing that the circuit was hot. When I’d wire up the GFCI, I couldn’t get it to turn on. I figured I had a bad outlet, so I swapped it for another, same issue. I tested them on another circuit and they worked fine. I then swapped in a normal receptacle. Same problem. When I tested the wires, they showed I was hot and had 100-120 volts. When I plugged those wires into something, the load dropped to nothing. My next test was to direct wire into a light bulb. I don’t recommend trying this at home as it’s pretty dangerous, but I couldn’t figure out who in this equation was lying to me. The light wouldn’t light. Don’t worry, I didn’t not take the next logical step and lick the live wire to find out if it was really hot. Instead I called Emily for advice.
She asked an electrical engineer she works with who suggested that the breaker was probably bad and the hot reading was really just leakage from the line and not a real load. Okay, sounds reasonable. So first we tested the existing breaker using a different multimeter that we knew not only worked, but was way nicer than the one I had previously been using. It showed the breaker worked fine. I went ahead and replaced it anyways. Same problem. The next step was to wind through the circuit path trying to find the geographic area of concern. We attacked this from both ends. I went junction box by junction box doing the same series of tests at each point where the circuit path was spliced. The good news is that each iteration of tests showed the previous area was fine. If it fails in the basement before it gets to the kitchen, then the problem can’t be in the kitchen. I also went back to the breaker box and directly wired an outlet into the breaker in question. It worked. So my problem was definitely in between the box and the last junction headed up into the kitchen. A few hours of testing more and I found the box the problem must be in. We replaced connectors and rewired everything in that box. Turned it on, and the light bulb lit up. I quickly wired it back together and I had power in the kitchen.
I’m still not convinced the problem is solved. It’s possible that we just switched circuit paths in one of the boxes. I didn’t have time today to turn everything on and verify that everything is working properly. And I still have a few boxes in the basement with all their guts hanging out. But I still don’t know what the cause of the problem was/is. Why would a wire read hot and then immediately drop to no load when something was plugged into it? And not just some random thing that would break the circuit. I was wiring it into a 60 incandescent light bulb. It wouldn’t light at all.
I really do like the logic involved in wiring. In a funny way, I feel more comfortable and less afraid of electricity than I do of plumbing. Sure, things can go wrong and you can die or burn your house down, but most of the time, if you’re meticulous and analytical, you’ll do a good job and be able to solve your problems.