Confusion over tripped breakers

Q. I was having trouble with a garbage disposal that was jammed and would not come on. I checked the breaker in the electric panel and it was off. I reset the breaker and it immediately went to “off.” I then turned off the switch to the disposal and reset the breaker and this time it stayed on. My wife, not knowing I had done this, came home while I was still checking the breakers and used the disposal and it worked just fine. Can you tell me why the breaker tripped twice and then everything was back to normal?

A. When a motor first starts, it receives an initial surge of electricity until the motor is operating at full speed. When the motor was “jammed,” the breaker tripped because the initial surge overloaded the breaker and the breaker tripped to prevent further damage to the motor and to keep the circuit wiring to the motor from overheating.

When you find a breaker that is tripped, and as you attempt to reset the breaker and it trips off again, do not try to reset it a second time. Doing so can cause serious damage to equipment on that particular circuit or the wiring to the equipment could ignite a house fire.

Call a licensed electrician before resetting a breaker more than once or if a fuse blows as it is being installed.

Never use a fuse rated higher than the one that was removed. Fuses and breakers are sized accordingly for the wiring circuits they protect.

In a residence, lighting circuits are rated at 15 amps, small-appliance circuits are rated at 20 amps and a clothes dryer and water heater will most likely be rated at 30 amps. There will be a label on the side of the air-conditioning or heat pump’s outside unit stating the maximum fuse size for that unit. Most are rated at 30 to 40 amps, but some are as high as 50 amps.

Here is what I think may have happened in your case: When you first tried the disposal, the motor received a surge that tried to start the blades turning. When the breaker tripped and you reset it with the disposal switch still on, the motor received another surge that tripped the breaker, but that surge freed the motor, so that when your wife tried it again, the motor was no longer “jammed.”

A “jammed” disposal can often be repaired using a broomstick to turn the blades inside the disposal’s drain opening. In the future, you should also check the reset button on the bottom of the disposal to make sure it has not tripped. It is another safety device to protect the equipment from overheating.

Ÿ Dwight Barnett is a certified master inspector with the American Society of Home Inspectors. Write to him with home improvement questions at C. Dwight Barnett at d.Barnett@insightbb.com.

Scripps Howard News Service