main tripping

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  #1  
Old 11-27-11, 05:05 PM
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main tripping

have a 100 amp service with approx 14 circuits in the house...on two seperate occasions the main 100amp breaker tripped...this happened approx 6-8 months apart...after resetting the breaker, everthing worked fine....on both occasions there was heavy usage in the house..is there anything to be concerned about and if there is what do i need to look for...Thanks
 
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Old 11-27-11, 05:30 PM
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You are using too much electricity all at once.

Or the other way to look at it...

Your electric system is undersized for the amount of electricity you need to use.

The budget way to handle this is to not use things which use a lot of electricity all at the same time. Like microwave, range, dryer, dish washer, things which heat like space heaters, hair blow dryer, deep fryer, etc.

Also an electric water heater will use a lot of electricity. So you could take baths/showers at a times when other things are not being used.

The other option is to have your electric service upgraded to 200 amps. You could call an electrician for an estimate on that.
 
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Old 11-27-11, 06:22 PM
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First though do you have electric heat, electric stove, electric dryer, electric water heater? Have you done a demand load calculation?

It could also be as simple as a weak breaker. You might want to have an electrician replace the main breaker first.
 
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Old 11-27-11, 08:18 PM
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Have you done a demand load calculation?
That's where I would start and then, look at actual loads with a snap on amp meter (Amprobe). If all looks good, balance your loads on the two legs. You could have a weak main breaker or bad connection to the bus at the main, but if that were the case I think you'd smell something hot and be having more frequent trips. Of course, the ultimate testing would be thermal imaging. What kind of panel do you have, who is manufacturer?
 
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Old 11-29-11, 04:48 PM
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we have a siemens panel...all major appliances are gas......how do i do a load calculation?.....how do you check to see if the main is weak or bad?....Thanks
 
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Old 11-29-11, 05:20 PM
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Dont know if this is related but I had an issue with my 200 amp service breakers radomly tripping along with the main at odd time.

Called the electric company, which you should do first so they can check thier end,

Comes to be the original 1950 ground compression coupling ( Dont know what its called) was bad. This was at the top of the home where the lines attach to the house. It was the bare aluminum looking wire. There was actually two of those joiners.

The elecric company cut both off and put one new one on. Something about the ground causing it and it was thier responsiblity.

In summary call the power company so they can check thier end, then take it from there.

Mike NJ
 
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Old 11-29-11, 06:33 PM
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Here is a load calculator. I haven't tested it. You can Google for others if you have trouble with it. Single Family Dwelling Electrical Load Calculator
 
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Old 11-29-11, 06:37 PM
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The budget way to determine if you are in fact using 100 amps is to total up all the watts or amps of everything which is on when this occurs. Many things have the wattage listed on the label. Some things the amps listed. You can convert watts to amps by using the calculators at the following. Use single phase and 120 or 240 volts...
Power Calculators for quick conversions.

Electricians carry an amp meter which they can "clamp" around a wire to tell you how much amperage is being used. If you get the electric company out there, perhaps you could turn everything on and they would be nice and tell you how much amperage you are using? (Offer them soda and cookies!)

Also I suppose you could learn to read your electric meter. Then turn everything on and time how much electricity is being used in a given time.
How to read a dial electric meter...
How to Read Your Electric Meter

Kilowatt hour - Wikipedia, the free encyclopedia
 
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Old 11-30-11, 05:13 PM
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Originally Posted by Bill190 View Post
The budget way to determine if you are in fact using 100 amps is to total up all the watts or amps of everything which is on when this occurs. Many things have the wattage listed on the label. Some things the amps listed. You can convert watts to amps by using the calculators at the following. Use single phase and 120 or 240 volts...
Power Calculators for quick conversions.

Electricians carry an amp meter which they can "clamp" around a wire to tell you how much amperage is being used. If you get the electric company out there, perhaps you could turn everything on and they would be nice and tell you how much amperage you are using? (Offer them soda and cookies!)

Also I suppose you could learn to read your electric meter. Then turn everything on and time how much electricity is being used in a given time.
How to read a dial electric meter...
How to Read Your Electric Meter

Kilowatt hour - Wikipedia, the free encyclopedia
While these and calculating your load are all good tips, these won't tell you if you have one overloaded leg. The calcs can indicate you are well under maximum wattage, but if one leg is overloaded, the main will trip. Your loads on each leg need to be balanced as well as possible.
 
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Old 11-30-11, 06:15 PM
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Trying to balance the loads on a single phase residential panel is an exercise in futility. The loads are too transient depending on the circuits being used. All the 240 loads area already balanced.
 
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