i took my car to the mechanic and couldnt get it to make that sound!

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aelectricalman

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KY
Well, the actually story is as follows;

I have been to the customers home 6 times already to attempt to repair a circuit which trip multiple times a days. The problem is that I can never catch it in the act. The homeowner tells me it happens at random times (seems to be more toward the night). The circuit has a DW, Disp, recess can, rangehood and receptacle on it. With everything running, I confirmed a safe circuit and no tripping. Infact, I metered the current and it read 9.5 amps on the 15 amp circuit at full capacity (minus the plug which isnt being used). This is really irrelevent, because she states that it randomly trips with nothing running. So, my question is how do I diagnose a problem if I cant catch it in the act, short of rewiring the whole circuit. Note, I tested the breaker and changed it out because the handle seemed a little rough, but the problem still occurs. Another thing to consider, the circuit is on a split 15 amp with another circuit on the same leg. The other circuit is fine. If anyone knows of any test equipment or inexpensive remedies, I would appreciate the help.
 
Time to break out the megger and spend a batch of time there checking the circuit out, or install a recording ammeter for a week or so.
 
megger = customer + $$$, recording ammeter was a thought

megger = customer + $$$, recording ammeter was a thought

Thanks for the suggestions. We were thinking alike Anyone else has an idear.
 
The circuit doesn't happen to do anything outdoors, such as heat tape, outdoor rec, post light, tool shed, or anything along those lines, does it?

A megger still gets my vote. A recoding ammeter may just tell you that you need to megger the circuit anyhow. ;) No better way to get a fault to declare itself.
 
Theres nothing outdoors. Just a motion sensor on a garage that I tested with my meter and tested the motion sensing, making sure the circuit didnt trip with motion. Everything tested fine. HUH. Nice thought however. Thanks.
 
With the megger, I will have to remove all lights and switches and everything from the home to test right? How much voltage do I crank it up to and how does that help. Rather, how do I view my results? Infared?
 
aelectricalman said:
Another thing to consider, the circuit is on a split 15 amp with another circuit on the same leg.
Just to clarify, are you saying that this circuit and another one share the same neutral, as in black-red-white? Or are you saying that this is a tandem (2-in-1) breaker? If both, that's a bad thing.

The black and the red must not land on two lugs of a single tandem breaker, but instead, each should be supplied from a breaker on opposite hots from one another.


Other miscellaneous thoughts:

Any GFCI devices involved?

Check the PITA-to-access recessed-light's J-box. Wirenuts like to jump off of fixture junctions. You should also open every box on the circuit to look for an intermittent short.

This seems to be a bit of a load for a 15a circuit. Are you sure there is nothing else on either of these circuits? Could there be another, unknown load, such as an exterior receptacle or crawl-space sump-pump?

Ask the homeowner to plug a clock into that unused receptacle, set it accuratrely, and note the time, and compare it to any activity. Better yet, ask them to also plug in a lamp or radio, so they can connect the event with something they're doing.
 
aelectricalman said:
With the megger, I will have to remove all lights and switches and everything from the home to test right? How much voltage do I crank it up to and how does that help. Rather, how do I view my results? Infared?
On second thought, maybe you shouldn't do a megger check. :grin:

Here's a thread in which I briefly touched on the procedure.

Your results are viewed on the screen of the megger. You want nothing to be less than 20 megohms at 500 volts (resi work) between any of the three conductors of the circuit.
 
"Better yet, ask them to also plug in a lamp or radio, so they can connect the event with something they're doing."

We had one like this, and when I looked at the recess lighting. it seemed like a pretty new installation, so I asked the owner when the recess was installed, they said their neighbor was a maint electrician, and he put them in, ok good place to start, I open the switch cover, and remove the switch, bingo, he tied the neutral to the ground wire, in the switch because there was no neutral in the switch box, hackers favorite trick, I removed the bootleg and rewired, tripping problem solved.
 
I would pop the covers off the appliances and look for a short,like under the DW,to start,and i never go by what the customer says,ask them what they do at night or if they have added anything lately, if not i bet you find it in one of the items you listed.I see wires come out of the wire nuts all the time, or get smashed against something ,you said recess can,i have found them shorted out where the cover had pinched the wire, a year later after being installed.It sounds like its shorting out then clearing itself for a while till something disturbs it again.
Good Luck.You will find it.
 
already changed breaker

already changed breaker

then swap top ckt with bottom ckt of twin and if it still trips you know you have a fault or an overload. Also check bus detail for damage or adjascent breakers with loose terminals that are causing heat heat rises so below is more suspect just check for warm to the touch or I also have a fluke thermal laser scan thermometer it is very inexpensive and is priceless for locating problematic breakers and loose terminals in a panel without taking cover off.
 
Have you swapped out the breaker? It just might be tripping at 10A. And IMO there is quite a lot on this thing, a hood, disposal and DW? Must be some older light duty stuff? Most newer equipment is >7A each these days.

I would gradually increase the load to 15A by adding some sort of load to it, and leave it at ~15A for a while (half hour), meanwhile go turning things on and off elsewhere in the house. Also, (assuming you haven't done so already?) open every box and check every splice. You might just have a dummy load via a loose connection. (Shutting off the other circuit prior, as you need to check the neutral too...)
 
My first question would be, ?How long ago did the symptom first appear, and was any electrical work done just prior to that time?? My second question would be, ?Has the symptom changed in any significant way, since it was first observed? In other words, did it first trip only once a week, did it then start tripping three times a week, and is it now tripping four times a day?? Someone has already asked my third question: ?Is it possible that some other load is on this circuit, and that that other load is the cause of the problem??

My first action would be to transfer the other load (i.e., on the split 15) to some other breaker (presuming that there is spare room available somewhere in the panel). If there is no available space, I would replace an existing single-15 with a split 15, so as to make room for the other circuit. You don?t have to leave it this way; this is just a simple and inexpensive test to see if there is an influence between the two circuits.
 
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