Service call

[sparky1118]

So I went to a service call about a week ago they had a 20 amp circuit that was tripping the panel is probably 20 years old. I figured the breaker was bad I did an amp rating on it and it wasn’t showing anything so I replace the breaker. The homeowner called me back and said that she was having issues again. So I went by yesterday and she had another 20 amp breaker trip and also a 15 amp breaker for the furnace. I reset the breakers and couldn’t find an issue. Well the breakers tripped again. This house has no major appliance draw minus the range. They did have solar installed about a year ago. I am totally stumped on this one....

 

[sw_ross]

My first thought would be something that is causing various circuits to short out...
Possibly those circuits are run together in a place (attic, crawlspace) where some rodents have access and have chewed on the wires?
Or solar installers drilled through somewhere to run their wires to the inverter and either damaged some wires, or gave an opening where rodents can get access into the attic?

Got to be a common denominator to those circuits

 

[ptonsparky]

What kind of breakers? GFCI?
Did you do any voltage checks. L1-L2, L1-N, L2-N?

 

[Little Bill]

Make sure they aren't plugging in space heaters in these circuits. In my area, that's the number one cause of breaker tripping and burnt wiring for this time of year. Especially if they're using extension cords.

 

[powerpete69]

Are they being short circuited in the instantaneous range or are they being overload in the long time range?
Sure would be easier if breakers indicated which one upon tripping!!

That being said, its most likely a overload as the short circuit would not allow them to be reset....hmmmm
The space heater idea sounds reasonable.

 

[synchro]

It's a stretch, but maybe a poor connection of the grounded service conductor to neutral bar could allow the L1-N and L2-N load voltages to shift as the loads vary. Then the L-N voltage on one phase would increase, possibly causing excess current through a load on that phase and trip a breaker. Something with a motor like the furnace could draw significantly more current when the voltage is higher.
If the neutral connection was poor then you might expect the homeowner to notice lights flickering, but who knows.

 

[mopowr steve]

Or it could be not even electrical at all, make sure someone’s not banging on the wall. Sometimes just mechanical shock can cause the internal latching apparatus in a breaker to trip.

 

[sparky1118]

It is not overloaded. One is a dedicated circuit to the furnace and the other is a kitchen circuit not overloaded


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[benmin]

Last call I had of a similar nature was caused by a screw. The 2 romex wires of the affected circuits were run up a stud together and hit by a screw through the siding. Try meg testing the circuits

 

[Another C10]

One thing I've learned about troubleshooting is get as much info from the client as possible like,

How long has this been going on.
Is it sporadic or fairly a routine time frame.
What were you doing during or recently when noticing this problem.
Did you notice an unusual Oder or hear any strange sounds.
etc ..

These may sound ridiculous but I have to admit many times I know exactly were to start before my questions stop.
Another important factor is know if you cant simulate , visualize or recreate the problem its not fixed.
When opening boxes or visualizing connections keep a close ear and observant eye, the problem may be right in plain sight.

Trouble shooting is an art and requires all senses and focus. I think its a great challenge.

 

[LarryFine]

Another question: "What does it take to be able to reset the breaker?"

Sometimes just mechanical shock can cause the internal latching apparatus in a breaker to trip.

I trip breakers in my hand on purpose that way.

 

[Eddie702]

I would ask if they have done any remodeling recently? Any evidence of water or moisture in the panel? Duk seal on meter socket , rotted cable letting water in?

 

[mopowr steve]

Screw barely breaching the hots of two separate wires, in this situation sounds pretty plausible.
Good luck finding it!

 

[Another C10]

I'm not sure if you got this resolved, if not one technique I've applied was to Isolate the circuits affected plugging or temp wiring the loads in question to an entirely different circuit. That way if the problem occurs with the furnace or kitchen circuits then you'd know it wasn't the prior systems branch wiring. So with that you could focus on recreating the problem by introducing the kitchen circuit back then if no problem still introduce the furnace, therefor pinpointing the common denominator. Troubleshooting any circuitry I've found works best if able to segment the system, isolating every aspect from the breaker to the load. good luck, keep us posted.