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BerzerkJ · Mar 27, 2007, 08:09 AM

Hi, I just have a couple of questions. First I have an old 60 AMP panel in my house, and I was wondering if that means the some total of all the breakers in the box should be less than 60 amps, or if that no one breaker should be more than 60.

Second. I want to wire 5 baseboard heaters in the house. 1 500 watt, 2 1000 watt, and 2 1500 watt. A total of 5,500 watts. I have read that the max watts you can put through a 30 amp breaker is volts*amp*80%. That means a 30 amp breaker can take 2880 watts. Since the heaters require a double breaker, (240 volts), does that mean the double can take 5760 watts, because there are two hot wires? (I am hoping yes, because then I would only need one 30 AMP double breaker to heat the house. I am also hoping that the answer to question one doesn't mean I need to install a bigger panel.

Thanks, any help would be greatly appreciated.

tkrussell · Mar 27, 2007, 02:18 PM

Adding the rating of each branch circuit breaker is irrelevant to the size of the service. The rating of the service only needs to handle the total actual load of all of the branch circuits, each will be less than the rating of each circuit.

5500 watts of electric heat at 240 volts equals 23 amps, which can operate on a 2 pole 30 amp breaker, and the entire circuit will need #10 wire.

I question whether the 60 amp service can handle this additional 23 amps, it may or may not, all depending on the existing load. This heat load must be assumed to be all operating at 100%. If you only have a few 120 volt circuits and no other electric appliances, you should be fine.

FYI, the minimum size service now allowed is 100 amps. If your insurance carrier does a loss survey of the home, they will require the 60 to be upgraded to 100 amps, so just be on the watch for this.

BerzerkJ · Mar 27, 2007, 02:42 PM

All right thanks for your help. Based on the fact that I want a dryer, and a hot water heater as well, it looks like I will have to change the panel for reasons other than insurance anyway. It is a Federal Panel from the 90s anyway, which are natorious for fire hazards.