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Old 08-23-2010, 06:59 AM   #1
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Circuit Breaker that trips slowly


Hi there,

I recently replaced the upstairs bathroom fan with a newer style (Broan economy - 0.9 amp).

Everything worked fine until later on that night the CB tripped. I re-set it and low an behold, I wake to find it tripped again in the morning.

I eventually took the fan and the fan casing back out and just have wires unconnected to anything (just wire nuts on them) to see if this would solve the breaker issue. I thought the wires may be touching the metal case causing an issue.

Now the power will stay on longer but it will still trip the breaker.

I have tried eliminating the problem by unplugging everything and systematically turning everything back on, but like the title of my post - the breaker does not trip immediately. It takes at least 10 mins so I can't pin-point the problem.

- The panel box is less than a year old.

- The new fan is actually less amps than the old one.

The 15 amp line feeds to:

- upstairs bathroom - One light fixture, one fan, one receptacle

- bedroom one - One light fixture, 2 receptacles

- bedroom two (spare bedroom-not being used) - One light fixture, 3 receptacles, nothing plugged in.

- Hall - One light fixture

Is there a reason for the breaker not to trip immediately? Like a slow build up of power?

I am really stumped and getting closer to calling an electrician, but I believe it may be something simple, I just keep missing it.

The breaker not tripping right away is what is troubling me. (loose wire maybe?).

Any ideas on what could be causing the problem?

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Old 08-23-2010, 07:53 AM   #2
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Circuit Breaker that trips slowly


I would start by replacing the breaker. When you replaced the fan, is it the same style? I mean.......is it a light/fan/night light combo, or just fan? Did you change anything else on this circuit prior to installing the fan? If its the same style fan and your wires are hooked correctly, it could be 2 things....either the breaker is bad or the light switch itself is bad. I would replace the light switch and breaker and try it again. If there was a wire touching metal or another neutral, the breaker should trip right away.........

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Old 08-23-2010, 09:34 AM   #3
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Circuit Breaker that trips slowly


A breaker that has a delayed tripp sounds like it is holding an overload until too much heat builds up.

A breaker that trips instantly is a dead short.
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Old 08-23-2010, 04:01 PM   #4
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Circuit Breaker that trips slowly


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Originally Posted by kskier View Post
I would start by replacing the breaker. When you replaced the fan, is it the same style? I mean.......is it a light/fan/night light combo, or just fan? Did you change anything else on this circuit prior to installing the fan? If its the same style fan and your wires are hooked correctly, it could be 2 things....either the breaker is bad or the light switch itself is bad. I would replace the light switch and breaker and try it again. If there was a wire touching metal or another neutral, the breaker should trip right away.........
Thanks for the reply.

Fan is the same design as original.

Nothing else on the circuit was changed.

As mentioned, the breaker panel is less than a year old so I wouldn't think it would be the breaker.

Not sure what would cause the slow build up and then trip the breaker.

Still stumped.

Thanks for the help though, every bit helps.
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Old 08-23-2010, 04:28 PM   #5
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Circuit Breaker that trips slowly


Check the wiring in the attic, maybe something got bumped against a nail or something and moves with the wind/air flow.
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Old 08-23-2010, 06:12 PM   #6
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Circuit Breaker that trips slowly


When you clamped the cable into the new fan did you tighten the cable to tight?It just needs to be snug enough to not move.
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Old 08-23-2010, 06:22 PM   #7
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Circuit Breaker that trips slowly


The quick way of determining if the breaker is at fault (before buying a new one) is to temporarily move the wire from the breaker that is slow-to-trip to the breaker next to it. If you get the same results as with the first breaker then the problem is between the breaker and the fan.

I had a similar problem recently with lights in the upstairs bath. Everythign pointed to a bad breaker. Turns out that the neutral wire (white) was loose at the breaker box.
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Old 08-24-2010, 07:02 AM   #8
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Circuit Breaker that trips slowly


Quote:
Originally Posted by Red Squirrel View Post
Check the wiring in the attic, maybe something got bumped against a nail or something and moves with the wind/air flow.
Thanks Red Squirrel.

I did check the attic after trying several other things and found everything in place and in good shape. (last resort, very hot up there, lol)

Most of the wiring is buried under the insulation so its not likely to get bumped.
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Old 08-24-2010, 07:12 AM   #9
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Circuit Breaker that trips slowly


I tried checking the receptacles again last night when I got home from work, for the possibility of loose wires.

What I didn't see the first time was that one of them had the wires on different 'posts/screws' than all the others. (Black on top screw/White on bottom screw -opposite sides of course).

All the other receptacles I checked either had the wires to the bottom terminals or to the top, not one to the top and one to the bottom.

I have switched them so they are both parallel with no sudden tripping of the breaker.

I don't believe this has anything to do with it but thought I would try it anyways.

The wires have obviously been this way for a while with no recourse, but I know sometimes the strangest things can work.

Thanks for all your posts, I will let you know if the power is still on when I get home.
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Old 08-24-2010, 08:21 AM   #10
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Circuit Breaker that trips slowly


"What I didn't see the first time was that one of them had the wires on different 'posts/screws' than all the others. (Black on top screw/White on bottom screw -opposite sides of course)."

if you look closely at a duplex receptacle, you'll see a shunt tab (one on each side usually brass colored) connecting the upper set of screws and contacts to the bottom set of screws and respective recptacle contacts. normally these tabs are left intact, so an "electrical junction" is formed between the upper and lower screws/recptacles. the tabs are broken when different power sources are brought in for the upper and lower such as a split receptacle, maybe one being switched.

if your tabs are in place, then the wires are at the same point electrically on top or bottom screws.
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Old 08-25-2010, 06:52 AM   #11
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Circuit Breaker that trips slowly


Quote:
Originally Posted by Jim Port View Post
A breaker that has a delayed tripp sounds like it is holding an overload until too much heat builds up.

A breaker that trips instantly is a dead short.
I am thinking overload may be the problem.

I went home last night and the breaker had not tripped (nothing was on of course, if so, only intermediately).

My son had his TV (no lights or anything else plugged in) on throughout the night and it still did not trip.

This morning however, while taking a shower (only thing on was the bathroom light & my sons TV), after about 10 mins the breaker tripped.

Questions:

- Would the condensation in the bathroom from the shower cause an overload?

- Would the fact that the bathroom light being on and then the breaker tripping mean that the problem lies within the bathroom?

Any suggestions would be appreciated


Thanks
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Old 08-25-2010, 08:46 AM   #12
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Circuit Breaker that trips slowly


A TV, Fan, and Light is not enough load to trip a breaker by itself. Condensation in the bathroom - maybe. Are the light and fan in the shower or just in the room.

Quote:
- Would the fact that the bathroom light being on and then the breaker tripping mean that the problem lies within the bathroom?
Not necessarily.

Last edited by a7ecorsair; 08-25-2010 at 08:49 AM.
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Old 08-25-2010, 11:48 AM   #13
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Circuit Breaker that trips slowly


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Originally Posted by a7ecorsair View Post
A TV, Fan, and Light is not enough load to trip a breaker by itself. Condensation in the bathroom - maybe. Are the light and fan in the shower or just in the room.

Not necessarily.
Just in the room.

Can't figure out what is causing the overload.

The condensation would be the same as its always been and never had the problem before, just when I installed/removed the fan.
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Old 08-25-2010, 11:56 AM   #14
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Circuit Breaker that trips slowly


You should really have a clamp-on ammeter to diagnose the problem. However, most (not all) circuit breakers have a thermal overload mechanism that gradually heats up as it's overloaded. It can take a while (minutes/hours) to trip depending on the load. However, once it trips, it doesn't instantly cool down, so if you stick around for the 10 minutes it takes to trip and then reset it right after it trips, you can see if it takes another 10 minutes to trip or goes again right away.

If it's right away, then it's probably just an overload. If it's 10 minutes again, then it's probably an intermittent load problem (such as an A/C). Regardless, I would recommend an electrician with proper tools measure and correct this. Trial and error breaker resetting is NOT recommended under any circumstances.

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Old 09-07-2010, 11:26 AM   #15
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Circuit Breaker that trips slowly


Thanks to all for your input.

The problem apparently was a loose connection (several acutally) in the new breaker panel.

Still under warranty so we had them come in and fix the problem.

Have not had any problems since, knock on wood.

thanks again.

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