lighting and receptacle breaker tripping

[LarryFine]

Are you assuming that there is something loose associated with the circuit that will be revealed by the light bulb while wiggling devices and switching loads?

Yep. I once used that method to troubleshoot an intermittent breaker tripping in an older house. It ended up being a cat-urine-soaked receptacle in a Wiremold box behind the front door.

The bulb acts as a current limiter, so the breaker won't trip. The bulb brightness, and steadiness of brightness, provide valuable clues. In my case, the bulb flickered as the receptacle arced.

 

[Ravenvalor]

Yep. I once used that method to troubleshoot an intermittent breaker tripping in an older house. It ended up being a cat-urine-soaked receptacle in a Wiremold box behind the front door.

The bulb acts as a current limiter, so the breaker won't trip. The bulb brightness, and steadiness of brightness, provide valuable clues. In my case, the bulb flickered as the receptacle arced.

That is a good one. They did not know the cat was urinating behind the front door I assume. How does the bulb act as a current limiter? Is it stored energy like a capacitor?

On a side note, your lightning avatar looks a little bit like my Tesla coil.

Thanks to all for the help.

 

[hurk27]

That is a good one. They did not know the cat was urinating behind the front door I assume. How does the bulb act as a current limiter? Is it stored energy like a capacitor?

On a side note, your lightning avatar looks a little bit like my Tesla coil.

Thanks to all for the help.

No a light bulb is a resistance, and resistance always is a current limiter, it allows to have voltage on a circuit limiting the available current to prevent damage (or fire) and have a way in indicate when you find the short and open it, I cant afford helper right now so I use a long 50' or 100' extension cord and do the same thing this way I can see the light go on or off as I wiggle the circuit conductors when looking for the short, no helper needed.
If you use a lamp socket with a switch, its also a good way to remotely remove power from the circuit when you go to undo wires or things.

 

[Ravenvalor]

No a light bulb is a resistance, and resistance always is a current limiter, it allows to have voltage on a circuit limiting the available current to prevent damage (or fire) and have a way in indicate when you find the short and open it, I cant afford helper right now so I use a long 50' or 100' extension cord and do the same thing this way I can see the light go on or off as I wiggle the circuit conductors when looking for the short, no helper needed.
If you use a lamp socket with a switch, its also a good way to remotely remove power from the circuit when you go to undo wires or things.

Amazing, I've been doing electrical work for 24 years and have never heard of this method.

 

[LarryFine]

How does the bulb act as a current limiter? Is it stored energy like a capacitor?

Nope. It simply limits the maximum current to that of the bulb itself if there's a direct short on the circuit; less if there isn't. The idea is to keep the circuit energized long enough to find the short. If the breaker instantly trips, you have no diagnosis time.

The current cannot exceed that of the bulb itself for the same reason you can use a voltage tester across a fuse to see if it's open. The load can't "force" more than the tester's current through it, so the tester won't explode because of the load.

 

[LarryFine]

I cant afford helper right now so I use a long 50' or 100' extension cord and do the same thing this way I can see the light go on or off as I wiggle the circuit conductors when looking for the short, no helper needed.

Yep. If I have a helper, I use a rubber lampholder and bulb in line with the breaker. If I'm alone, I'll use a receptacle, and plug in a cord and a lamp.

In either case, I use a 100 watt bulb. A radio or other noisemaker can be used for circuit ID when alone, but a bulb is a must for troubleshooting.

 

[LarryFine]

I remember from way back in my Popular Electronics days an article about building an electric-train power-pack. A pair of 12v bulbs in parallel was used as a track-current limiter. The cold filaments had little resistance, but a short lit them up and indicated the short.

Amazing, I've been doing electrical work for 24 years and have never heard of this method.

You're right: that is amazing.

 

[highvolts582]

noooooooooo it fixed itself

noooooooooo it fixed itself

When i am trouble shooting there is nothing worse than the problem working when you get there or fixes itself while your working and you don't know if you actually found nailed down the issue. god help anyone this happens to. and if your not really sure you can almost bet on a call back. even worse its in the wall.... get the axe out.

 

[Ravenvalor]

Yep. If I have a helper, I use a rubber lampholder and bulb in line with the breaker. If I'm alone, I'll use a receptacle, and plug in a cord and a lamp.

In either case, I use a 100 watt bulb. A radio or other noisemaker can be used for circuit ID when alone, but a bulb is a must for troubleshooting.

I see, do not connect the light bulb to the neutral but to a hot going in and a hot going out.

Thanks,
Jim

 

[zog]

That is a good one. They did not know the cat was urinating behind the front door I assume. .

How is that possible?, cat pee is about the worst smell in the world.

 

[LarryFine]

I see, do not connect the light bulb to the neutral but to a hot going in and a hot going out.

Exactly. The black wire on the breaker terminal, and the white wire wirenutted to the circuit wire, so the bulb is in series with the circuit.

 

[LarryFine]

How is that possible?, cat pee is about the worst smell in the world.

It's amazing how bad it can get and still be tolerated by cat hoarders.

 

[Dennis Hamilton]

Breaker Trips once daily.

Breaker Trips once daily.

A 5 - year old home has a lighting and receptacle circuit tripping a circuit breaker. The breaker is 15amp and not an arc-fault. Since it is only doing it once daily I would like to find or develop some machine that will locate the assuming short. When I get to the home it will not be tripping therefore I need to find a short that is not occuring in my presence.
I am an electrical contractor who has been fixing these types of problems for 24 years. Usually I have to check every accessible part of the circuit including the appliances. I am wondering if there is a theorem associated with ohm's law that will enable me to calculate varying voltages and amps at each outlet to reveal the short.

Thanks,
Jim

I had a service call were a fuse was blowing every day. When the customer came home from work, he would have to replace the fuse. Everything was fine until he came home from work the next day. I checked all the curcuits and found nothing wrong. Went out to the van to get something, and while walking back to the house, I noticed a roof fan on the back side of the roof. Went up in the attic and checked it out, and found the fan blade came loose, and slipped down and jammed the motor. When the thermostat cam on after they had gone to work, the fuse would blow due to the motor being jammed. By the time they came home the thermostat had turned off, allowing a new fuse to work until the attic got hot the next day. They had just moved in the house and didn't know the fan was up there.

Hope this helps.
Denny

 

[Ravenvalor]

I had a service call were a fuse was blowing every day. When the customer came home from work, he would have to replace the fuse. Everything was fine until he came home from work the next day. I checked all the curcuits and found nothing wrong. Went out to the van to get something, and while walking back to the house, I noticed a roof fan on the back side of the roof. Went up in the attic and checked it out, and found the fan blade came loose, and slipped down and jammed the motor. When the thermostat cam on after they had gone to work, the fuse would blow due to the motor being jammed. By the time they came home the thermostat had turned off, allowing a new fuse to work until the attic got hot the next day. They had just moved in the house and didn't know the fan was up there.

Hope this helps.
Denny

Quite helpful, for every occurence there is a logical cause.
The light bulb short circuit finding method is helpful also. I wonder if it will also help when the circuit breaker is an AFCI.

Thanks,
JB