How can I figure out why my breakers are tripping?

Question

A few years ago, I installed a solid wood "pocket" sliding door for my workshop. It's on an exterior wall, so I had to add some thick sealing strips that keep the cold air from Wisconsin winters outside. As a result of the heavy material and tight-fitting strips, the door can be a bit of a bear to open – especially with one hand.

Last summer, just when I was about to remove the stripping, I spotted a garage door opener at the flea market and had an idea. A few days and a couple gears later, and I had a door that would slide open and closed very quickly through a foot pedal (requiring zero hands) or an outdoor keypad.

Just recently, however, I've been having a few obnoxious electrical issues. About halfway through the door opening, a breaker will trip… losing all power. Normally, this wouldn't be a big deal to diagnose, but the wiring is a bit weird.

I have two electrical mains (the garage requires a separate electrical company account being on a separate property), but the previous owner wired the house, garage, and workshop together so that you could turn outside and garage lights on/off from various switches.

Sometimes a breaker in the house will trip, and sometimes a breaker in the garage will trip. The workshop is supposed to be wired to the house's electrical line, but the house will trip about 30% of the time instead.

It's not a big deal to flip the breaker, but I'd like to figure out where my problem is so that I can use my sliding door like I have been.

Answer 1

First, breakers are designed for avoiding draw over the rated current - old fuses did this by melting when the line in the fuse got too hot and melted. They are not designed as switches for operating a circuit, so your statement "It's not a big deal to flip the breaker" is only in reference to the amount of inconvenience you suffer. The breakers should not be flipping constantly.

The reason most breakers flip is when you run a motor that pulls more current than the breaker is rated for, so the simple fix if things were wired correctly would be to use a lower amperage motor or a higher amperage breaker. The risk with the higher amperage breaker is that the wiring in the wall is of insufficient gauge and will generate enough heat due to resistance to melt the insulation and cause a short.

The fact that the motor is apparently on more than one branch circuit is the primary cause for concern. This is a wiring issue, and can be solved by isolating the motor on its own new branch circuit. That will not solve the underlying issue of having (probably) multiple instances of poor wiring.

As far as diagnosing the specific problem goes I would recommend hiring an electrician to trace the branch circuits involved (you could do the same with a continuity tester and a few long leads) and write up a proposal to fix the wiring issues.