Old Zinsco Circuit Breaker Couldn’t Take Any Load

My tenant complained that the outlet for the refrigerator didn’t have power and he had to move to a different outlet to get power. The same problem happened to a couple of outlets around the kitchen.

I immediately suspected that the circuit breaker was tripped. But the tenant insisted that he played with the circuit breaker already without success. Then I got worried. Something is shorted and it’s not easy to find the shorts if they are internal.

When I got there, I waved my magic touchless electrical sensor and found that outlets were not hot (no power). So played with the circuit breakers and found that the outlets could be hot if there was no load. But as soon I plugged something in, the power went out. This is actually good news. Because it pointed to the circuit breaker couldn’t take the load – no shorts.

The circuit breakers are of the Zinsco type, manufactured by Connecticut Electrics. They are expensive ~ $50 each, a cash cow business for the company as the parts are no longer used in new homes. But they were installed in so many old homes including my apartment. Fortunately, I was able to buy it at my local Lowe’s Store. Home Depot had them too but more expensive – unusual that it’s more expensive at Home Depot than Lowe’s.

I was able to replace the 20A breaker and fixed the problem. In fact, I replaced one of the 40A oven breaker too as it was pretty loose – didn’t want to do this again. It took some maneuvering to remove the old breakers but the new breakers took care of the problem.

The lesson learned is that the circuit breaker can have a failure mode of tripping on very low load. This is good actually because it prevents the more sever failure mode of not tripping when it should be.

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