Federal Pacific 100amp panel Main Tripping


Old 04-27-12, 10:45 PM
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Federal Pacific 100amp panel Main Tripping

Hi there

Have a FPE 100a panel that has been tripping the main breaker. Looking in the panel Noticed the 240v H2o heater was wired 120v on 12/2 line on a single 20amp breaker. With a clamp on amp meter I was reading 18-19 amp draw on the hot wire and going back on the neutral. The 12/2 line was warmish and the supply line from the main breaker to the bus bar was also warm. I noticed that the supply line to the top of the bus bar was copper and the supply to the bottom was aluminum. It was the aluminum supply that was getting warm. Could this create enough heat to flip the main?

All the connections are tight and there are no visible signs of heat damage in the panel.

Any thoughts?
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Old 04-28-12, 03:27 AM
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The hw heater could have a bad element.
What is the draw on the 100 amp breaker...............Test the load with the hw water turned off then on.
Old 04-28-12, 03:57 AM
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IMO, the water heater needs the most attention. It should be wired properly to a properly sized breaker. Normally a 30 amp double breaker with 10-3 cable or wire in conduit.
Old 04-28-12, 05:47 AM
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I think I'd start by checking the actual elements in the water heater to see if they have been changed to 120 volt elements. If they have been changed to 120 volt, check the wattage rating on them. Even if they have been changed to 120 volt, you still have a problem with the circuit and breaker being undersized. If they are 240 volt rated elements, you need to install a proper 30 amp circuit on a 2 pole 30 amp breaker. Next, check the amperage being drawn through the main breaker. Your description sounds like a split bus panel so I am wondering where this 100 amp main is located. Is this a lighting main just for the lower lighting section of the panel. That's enough for troubleshooting for now. If this were mine, I'd replace the dangerous FPE panel with a good copper bus main breaker panel.
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