100 Amp Service Problems

Last Edited By Krjb Donovan
Last Updated: Mar 10, 2014 02:59 PM GMT

I am renting a home that was built in the 50's and still uses the old fuses and only has 100 amp service. My question is whether or not this is enough for the home. We have a lot of electronic devices that are usually plugged in and running. My fear is that the few issues I've had with appliances are to do with the appliances or the electric service in the home. I have had fuses blow left and right using one outlet so we don't use it anymore. My microwave has started sparking, and we had a space heater melt into the outlet. Is this just a string of bad luck or do we need to have a home with 200 amp service?


You probably have two issues. In addition to having only 100 amp service, the wiring is old. The outlet that is not working should be fixed so that it is not a fire hazard. The microwave sparking is probably not a wiring issue.

I do not like space heaters at all. They are fire hazard, both from the heat they produce, and from the power they use. If you use one, you can't have anything else on that circuit. It just uses too much power.

While 100 amps may not be enough for many houses, most likely the problem is overloaded individual fuses. If you have an electric range, dryer, A/C, hot tub, welder, etc., then you may need more amperage overall. But most likely you are blowing the individual fuses because too much is on each circuit.

See if you have one or two circuits for the kitchen outlets. If you have 2, then make sure you divide up what you use over the circuits. If you have only one, you may be able to use only one heating appliance at a time.

All of the issues are caused by the age of the wiring, so if you moved into a newer house, you wouldn't have most of the problems. But if someone upgraded the service to 200 amps where you are without changing and repairing the wiring, it won't help.

You may need to look at the wattage of each appliance you plug in. If the circuit was made for 15 amps, that is only 1800 watts max, including any lights, etc., on the circuit. If the circuit was made for 20 amps, then that is 2400 watts max. Do not put a 20 amp fuse if you are not sure the wiring is 12 gauge copper. (14 gauge is smaller even though the number is bigger) because it would be a fire hazard. It is best not to go as high as the max to allow some margin of error.


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