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panhandlion 11-25-2007 06:37 PM

20 Amp Breaker only trips once in a while
I have a 20 amp breaker that all of a sudden trips sporadically. Replaced the breaker and it got better (thought it was a bad breaker) but it tripped again. No overload of the circuit is evident and no new appliances added. It doesn't trip all the time just once in a while (enough to make me worry). There is also a GFCI (receptacle type) on part of the circuit but it never trips. Most "standard" trouble shooting so far has gone for nothing... ANY ideas?

RichyL 11-25-2007 07:02 PM

Need more info. Did you check voltage on the circuit when it is on? What all is on that circuit. Is the circuit outside/inside? Does it trip by itself or only after you plug a cord into it or try to use it.

panhandlion 11-25-2007 07:13 PM

I have not checked the voltage yet.

It is an inside and outside circuit (right now nothing is plugged in outside)... it trips by itself with no rhyme or reason... not just when a cord is plugged in, a switch thrown or anything like that...

I have come home to found it tripped when no one else was in the house... the only thing on it that could turn on by itself is the computer... every once in a while the fan kicks on inside the computer.

The outlet the computer is on is part of the GFCI portion of the circuit... the GFCI doesn't trip... just the 20 Amp breaker out in the panel in the garage.

Thanks for your reply and any added help you can provide.

RichyL 11-25-2007 07:27 PM

I would put your computer on a surge protector power strip, and i hope that your outside plugs are also gfci protected, with a weatherproof cover.
I have seen outside plugs trip the breaker on rainy or damp days where there is no weatherproof covers on them, or the cover is open and plug is exposed. You say your gfi doesnt trip? So when you hit the test button it does nothing? Make sure your connection is tight in that gfi, then again there may be a bad gfi that needs replacing. Is this a problem that just started recently or has it worked fine in the past, and has any of the wiring been changed to your knowledge since(if)it was working?

panhandlion 11-25-2007 07:31 PM

the gfci doesn't trip when the 20 Amp breaker trips... it does trip when the test button is pushed...

this circuit has NEVER given a problem in its 5 years (brand new house) of existence... all of a sudden it trips once in a while...

I am thinking I need to start checking for loose connections in all the boxes...

There really has been no additions or changes to the circuit for this to be happening now...

could a fan in a computer draw enough current to trip the breaker??? I would be shocked if it could...

also... no rain here ... middle of a drought


HouseHelper 11-25-2007 07:40 PM

Are there any appliances plugged in to this circuit such as a freezer or refrigerator? A bad compressor could cause the trip. Also, a damaged buss (where the breaker connects to the panel) could be causing the breaker to overheat and trip.

RichyL 11-25-2007 07:42 PM

could a fan in a computer draw enough current to trip the breaker??? I would be shocked if it could...

I would say no, those fans dont draw very much at all. Although it could possibly have to do with your computer equipment. You might wanna try and see if the breaker is still tripping with your computer equipment unplugged from that circuit and go from there

Stubbie 11-25-2007 07:48 PM

First breakers trip for two reasons over current and overload. Sounds like from you description the breaker is tripping on an over current event. So an investigation into all the electrical boxes is in order. Look for arcing or any thing that may be loose that might cause a short tripping the breaker. There is also the possibility that you have something that is on a timer or motion sensor that is tripping the circuit when it turns on its load.

Speedy Petey 11-25-2007 08:44 PM

A bad connection can "fool" a breaker into tripping the thermal overload portion. We see this with a loose connection at the breaker or neutral in a panel. Same thing can happen at a device.
I would check EVERY receptacle on that circuit for a loose, even burned, connection.

elkangorito 11-25-2007 09:33 PM

The only other thing that can cause this kind of spurious tripping is the presence of Current Harmonics (such as created by "switch mode" power supplies). An indication of these harmonics is usually presented as a higher than usual neutral current.

For how long has the computer been connected to this circuit? Is the computer always left switched on?

panhandlion 11-25-2007 09:49 PM

The computer has been on the circuit for years... same computer...

Yes, it is always on...

elkangorito 11-26-2007 08:35 AM

There is a slight possibility that the computer power supply is failing, causing the spurious tripping. Also, other harmonics being introduced by the general neighbourhood could also be a factor.

As an aside, hydraulic-magnetic circuit breakers will not be affected as much as thermal-magnetic circuit breakers are under these conditions. Mind you, you will pay extra for these breakers. Hydraulic-magnetic breakers are the "Rolls Royce" of circuit breakers whereas "thermal-magnetic" breakers are considered to be the "Ford".

I used to work for Heinemann who manufacture Hydraulic-magnetic breakers. They are more expensive but are far superior than thermal-magnetic breakers.

panhandlion 11-26-2007 05:00 PM

The power supply for the computer is getting noisier as it ages... also the fan kicks on often which may be the power supply overheating... I think I will try that first... the neighbor is a comuter geek and can probably swap it out for me...

Thanks for the responses... any others???

RichyL 11-26-2007 08:31 PM

The computer is the only known load on the circuit you speak of. When you unplug the computer equip. and the breaker is still tripping, then it is probably something going on in the wiring, like a loose connection or arcing somewhere, unless you have something else plugged in on that circuit that is tripping it or overloading it , which you say it does not. If the breaker is only tripping when the computer is plugged in its probably your equipment needs some repair,

panhandlion 11-26-2007 08:36 PM

I think I am going to run an extension cord from a separate circuit for the computer for a while and see if that is the problem... maybe the other circuit breaker will trip (indicating the computer is the source of the problem) or the original circuit will trip again without the computer and i can go from there...

last two days just one trip... this is freaky!!!

Thanks for your help so far!!!

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