random tripping of breaker troubleshooting help please

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kevyank1918

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raleigh, north carolina
looking for a few ideas to help with troubleshooting breaker tripping....customers house breaker is tripping at random times (never while on sight) here's info I have done so far:
-breaker feeds bathroom exhaust fan, bathroom vanity light, 1 bedroom light and receptacles in that bedroom
-breaker is not arc fault or gfi standard square d qo load center snap in breaker
-breaker trips at random times with nothing plugged in or lights on with this circuit, sometimes while thay are at work; sometimes in the evening while they are sleeping, sometimes while they are at home
-I have changed breaker in the panel and checked panel connections and bus bar where breaker snaps in (also moved to different location)
-14/2 wiring, not sharing neutral with another circuit
-checked devices, lights, fan for wiring problems
-took amp draw with circuit on and everything turned off to make sure no other load on circuit that I am unaware of
-spot traced wire from panel to 1st entry point does not appear to have any junctions underhouse (when I say spot traced I followed group of wires from under panel to where they enter walls under house and there were no junctions I did not actually follow that wire all the way knowing for sure that was right, this was on my 1st visit I probably need to 100% verify)
-my next idea is to break joints at halfway point, or somewhere along the line and see if it trips and go about with that way of process of elimantion

would like some ideas/advice/questions on stuff I've checked to see anything I am missing or am not thinking to check

thank you
 
Some thoughts

Some thoughts

I'm sure there will be some additional expertise from other members offered.
I am assuming a 15A circuit since you mentioned 14 AWG.
If it is definite that you are tripping with zero loads engaged then there must be a fault phase to N or phase to ground which is intermittent.
I have dealt with similar on 460V wires in conduit only.
The offending portion of the line, or if a load is suspect will have to be " isolated."
EG , If the major home run can be replaced by a temporary run and the problem still happens it is downstream and can then be ruled out systematically by removing portions of the branch or loads. All junctions and wiring devices ruled out.
On another note this is most likely unrelated, but I have been involved in a structure fire that was cause by a " Broan " bath exhaust fan. which happened on a facility I was employed on. It was a mechanical locked rotor fault that allowed the shaded pole motor to get extremely hot without overloading the 20A circuit. There are apparently other documented cases of the same failure with the same outcome.
 
thank you for your thoughts, this one is racking my head, first i'm trying to think what is causing it, staple, hungry critter?? also my line of thinking of replacing the homerun I don't know whether to replace wiring intermittently as you stated or start breaking apart connections intermittently guess I need to talk to customer to see what they would prefer, replace wiring and wait and see or break connections and wait and see, either way i'm sure it's aggravating for them....interesting note on the fan I need to replace one in my bathroom this weekend that has gone bad, not going back with the broan now, thanks!
 
The homeowner knows it is tripped because now they check it when they get home/ wake up. At first they did not know conditions of tripping. I have been working with them as far as making sure they leave everything off on circuit, plugging accessories into different circuits. On my first visit I found that a light they had replaced had the wirenut over tightened where the end of the wire (switch leg) was sticking out of wirenut, suspected this to be the problem (nice easy fix huh) and repaired it. After we realized there was a different problem we have been troubleshooting to see when/what conditions are present when breaker is tripping.
 
supposedly this is all because I asked what else they have touched but I was just reading a different post where customer says: breaker tripping in the middle of night, what the customer didn't say is they wake up and heat up milk in microwave in middle of night when they can't sleep and breaker trips as soon as microwave turns on....funny but scary...I went to office building the other day and customer had wall motion switch in office said it wouldn't work by push button and someone else tried it and wouldn't work several times...after more coaxing from customer to find out when it happened it always happened Saturday when they worked and Monday it was fine, her office motion was tied into hallway switchleg instead of hot so on the weekend when no one was working and hallway lights were out her office motion would not work
 
My guess would be that if the cable is stapled to the floor joists, that you may have a staple in a wire and as they walk on the floor something rubs and trip goes the breaker.
 
Tell them your price cause your ready to fix it. ;) That's all you need to say, next

Then this is when you ask the patron what music they like and play a radio and ID the circuit. every other circuit is off.
Draw a napkin sketch.

You could also use a fox and hound which will cause static on a radio, OK my type of equipment does.

This is exactly where you could insert a AFCI and confirm the other statements, go no go.

Then a Meggar would then work well for you, work everything off the circuit breaker. circuit to Breaker is disconnected. I'd Half the circuit and use this test going out on that amount of the circuit. Then reattach breaker you could test load, hair drier - that part of circuit. This will help qualify the insulation going out and QA breaker is doing what it suppose too. Move forward!

MY call you'll find it pinched or worked from being on or around other piping, then it a device that's loose or tired, even
a staple which will not get pass a AFCI.

This is exactly why we just had or going to have Fire Prevention Week / Month / Moment... Weather change & Movement.
 
The cause of the trip should be considered.
It important that the homeowner be present when the breaker trips. If it trips instantaneously the breaker will be cool to the touch and can be latched and closed without a problem.
If the breaker tripped on thermal it will most likely will be warm to the touch and can not be latched and closed until it cools down a bit.
That will at least get you started on locating a possible failure to look for.
Also, confirm that there isn?t a connection to the breaker that can cause heating. Take a look at the stab connections and load center bus for signs of heating. Since you have replaced the breaker the load side connection most likely isn't an issue.
 
mjf said:
Find out what else besides the luminaire the HO has replaced themselves.
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ActionDave said:
Good call.
The other thing I would do is leave the breaker off for a good spell. There may be something on the circuit that no one knows about yet.
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To elaborate, find out if they've been doing any landscaping, hung a new picture, stored some new stuff in the attic, etc, etc.

Does this occur when it's real windy or raining?
 
Intermittent problems are real buggers. You can spend a lot of time with these and that time is hard to bill for.

I would have the customer keep a log with info about the tripping.

Day, date, time discovered, weather condition, if customer witnessed the trip or discovered it at a later date, etc. Look for a pattern. Also, quiz them as to the exact date the very first time this happened.

The other option is to isolate parts of the circuit until the breaker stops tripping. Due to the intermittent nature of the trips, this may take several tries over several days and require several re-visits.

A data logger would be a great tool for this job. It would, at least, show of the overcurrent was immediate, like a dead short, or gradually rose, like a fault with some impedance to it. The data logger would also show the exact time of the trips, which may be valuable information.
 
It could be just about anything. I hate intermittent stuff. I usually end up declaring victory when it stops, even if it is never really determined what was wrong to begin with.
 
ActionDave said:
Good call.
The other thing I would do is leave the breaker off for a good spell. There may be something on the circuit that no one knows about yet.
Click to expand...

I would certainly urge you to take Dave's suggestion. I would also move the circuit to another slot in the panel to see if there is something about the panel itself. It is possible that someone borrowed the neutral for another circuit, but that would not overload the breaker, I think.
 
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