Electric Service

Old 07-04-02, 05:00 PM
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Question Electric Service

In my camper I have a 30amp main breaker and then a 20amp breaker and two 15amp breakers. It's fed from the middle of the campgroud with a 20 amp breaker so needless to say, if i have an overload, none of my breakers kick, the one out on the pole does and i have to have someone come down and unlock the box and reset it. If i change my 30 amp main to a 20amp, will my 20amp kick before the one out on the pole or should i change all of them to 15 amp breakers?
Thank for your help.
Old 07-04-02, 05:43 PM
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Just stick to all 15 amp and you won't have any problems.
Old 07-04-02, 06:02 PM
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I would disagree. The characteristic of a 15 and 20 amp circuit breaker are very similar unless the problem is an overload close to the trip value of the breaker and remains for 10 minutes or so.
It is probably a manufacturing anomaly that your 30A main doesn't trip simultaneously with the 20A service breaker. Manufacturing tolerances in these size breakers have a relatively wide range and are not predictable.
Don't let me confuse the issue, it might be worth to try to change all your breakers to 15A and see what happens, but it would be just a fluke if it works.
Although a bit difficult to follow, the link below is the characteristic of a small breaker similar to what we're discussing (typical GE Q-Line breaker).
The second drawing indicates a 15-50A circuit breaker. The only part of that characteristic that moves between a 15, 20 or 30A breaker is the part above 10 minutes and that moves so relatively little, that its characteristics overlap (possible simultaneous tripping).
Old 07-04-02, 10:45 PM
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I mostly agree with HandyRon. If the trip is caused by a short-circuit, then it's just a crap shoot as to which of the three breakers in the chain will trip. The short circuit can cause many thousands of amps to flow -- plenty enough to trip any of the three. Once one of them trips, there is no reason for the others to also trip.

But if the trip is an overload, then reducing the size of your breakers might help.
Old 07-05-02, 10:40 AM
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The main breaker carries the sum of all the other breakers in that panel. If the main breaker in your camper panel is 10 amps more than the 20 amp breaker in the camp site service panel then the service panel will trip first if your total camper load on your 30 amp main breadker exceeds 20 amps.

IF you want to avoid that then you must install either an inline panel with a 15 amp breaker in it so that 15 amp main breaker trips before your camp site 20 amp breaker trips.

If you installed a 20 amp main breaker in your camper then you stand a 50 / 50% chance of either the camp site breaker or the camper main breaker tripping because they would both be equal in amp rating.

HOpe this helps


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