Blown Breakers

It is not normal for a breaker to trip on a regular basis and if you have one that does that you have a problem that needs to be found and eliminated.

Household circuits, except those going to heavy use appliances like a dryer, range or hot water heater, can handle a sustained total load of about 1,500 watts. If the breaker always trips when you plug in or use a particular appliance you are apparently drawing more than 1,500 watts on that particular circuit.

Use a circuit tester (light, radio or commercial tester) and find all the outlets and/or fixtures that run off that particular circuit and add up the total watts of power they draw. Subtract that total from 1,500 to determine how much more power can be drawn on that circuit without problem. For example, a bedroom circuit may have two 100 watt bedside lamps, a 40 watt clock radio, and a 100 watt electric blanket. You then you have (1,500-340)=1,260 watts available.

Now suppose you buy a electric heater to take the chill off on cold mornings. Heaters, especially on the high settings, often draw almost 1,500 watts by themselves. That will probably be OK because you won’t have all the lights on at the same time, the heater itself cycles on and off, etc. However, now plug in your blow dryer!! The blow dryer probably draws 750 watts. If the heater is on at the same time the breaker is going to pop. If the heater is cycled off things will be OK until it comes on.

Thus you can have a situation where the heater is set to a lower setting so it cycles on and off but is not drawing power much of the time. When the hair dryer is turned on during a heater off cycle, everything is fine. However, when the heater turns back on the breaker is going to pop. This can be confusing because everything worked for a while and it may not be obvious what is going on with the changing current demand on the circuit.

{ 2 comments… read them below }
Anne Feig
I have a 19971 mobile home in really good condition but sometimes we blow some of the breakers and not sure why or how to fix this problem. I am wondering how all the wiring is run. Is the wiring under neath the house or is it ran through the walls or ceiling? Can some one help us with this.

I have never seen wiring diagrams for mobile homes. I think the manufacturers keep them very closely held and destroy them after a particular model is discontinued.
I would suggest buying a cheap circuit tester (or use a lamp) and turning off your breakers one at a time to see what works and doesn’t work. That should let you map all the outlets/devices on each circuit. Then check to see how many watts the appliances you have on each circuit add up to. If that number is getting close to the limit for the breaker you have found the problem. At this time of the year the most likely problem is a heater that cycles on and off. If it comes on at the same time as some other heavy power user the circuit breaker trips.

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  • My main in my trailer keeps tripping. I’m told the single pole main is supposed to be a double pole, but it’ll hold for several hours and then trip over and over for a few hours. The only consistent appliance relating to the trip is the a/c. Though, it has a separate breaker that does not trip. I figure the main needs to be replaced but am also afraid there is a short somewhere that I do not have the expertise to diagnose and we cannot afford an electrician. Thoughts?

  • Hi Allen,

    This is one of those situations where there are too many unknowns for me to provide a safe/accurate answer.

    Is there any chance the power company would check out there end. Otherwise, I don’t see any way to avoid a electrician.