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ceb58

ceb58

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Raeford, NC
I had a problem at work the other day with a breaker triping. 20amp circ. feeding recpts. cloth wire ran in ridged cond.,2 wire no egc about 40 years old. Things I knew, the home run landed in a box with a recpt. from there it split going up in cond. to feed 4 clock recpt. in 4 different rooms, the other wire went down and chained through 6 recpt. in 2 rooms. the rooms had work stations built over most of the recpts. Could not get to them except for tearing the work stations out. Trying to figure out where the fault was with out 2 days work tearing out and putting back the work stations. An older maint. mech. told me he would show me a easy way. We removed the panel cover, he removed the ungrounded cond. from breaker, he then put one cond. from a rubber lamp holder under the breaker. He then connected the other lead from the lamp holder to the wire. He had a 100w incond. bulb in the holder. We went to the box with the HR we disconnected the wire going down so only the clock recpt. would be on the circ. He closed the breaker all recpt. ok. We then reversed the connections to the wall recpt. closed the breaker, bulb lit up but breaker did not trip. He sad the fault was in the wall recpt. circ.
We then went to #5 recpt we could get to it easy. Disconnected the recp. and closed breaker. Lamp did not burn, recpt. 1 thru 4 were ok. He then said problem was between 5 and 6. Move a desk and pull #6 apart leaking pipe had filled cond. with water. Never seen the trick of using a lamp between breaker and fault befor
 
My father use to take a 100 watt bulb and screw it into the old fuse blocks. If there were a short the light would burn. We would go through the circuit until the light went off. Of course, you have to turn off all light switches in the circuit first. Works well. A 60 watt bulb would burn out-- you needed a 100 watt bulb.
 
Dennis Alwon said:
A 60 watt bulb would burn out-- you needed a 100 watt bulb.
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That makes no sense whatsoever to me.


10 watt or a 1000 watt would all work equally assuming the correct voltage.
 
Look into getting a Harris TS-90. I've been experimenting with it, with good results, versus a full blown TDR. It's been accurate within a foot for NM cable and old BX cable.
 
Hold up there cowboys, I thought the circuit was completed on the RMC.
He removed the ungrounded cond. from breaker, he then put one cond. from a rubber lamp holder under the breaker. He then connected the other lead from the lamp holder to the wire.
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I can only assume thats I'm wrong on that.
We then reversed the connections to the wall recpt. closed the breaker, bulb lit up but breaker did not trip. He said, the fault was in the wall recpt. circ.
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Could someone line diagram this! Cuz I know the surf is up somewhere, cause this went right over my head! :roll:
 
Why was a light bulb necessary?
It sounds like the tests that you did could have been accomplished with using the breaker??
Step 1) You isolated the two "halfs" of the circuit at the junction box with the receptacle. One half feed the clock circuits, the other half fed the 6 receptacles. Using the light bulb you knew that the fault was in the receptacle half of the circuit. The breaker would have indicated the same thing by tripping??

Step 2) Isolate a portion of the daisy chained receptacles by breaking the chain at receptacle 5. No light going on....OR the breaker would not have tripped. Same result, no light needed.
I don't get it. Why the light bulb??
 
jjhoward said:
The breaker would have indicated the same thing by tripping??
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Yeah, but why trip a breaker 900 times when you can just have a test lamp going on and off? It's the difference between professional service and some guy with half a clue.

I am reminded of a service call from 2 or 3 years ago where the building owner actually kicked one electrician off the job. They came from the largest and most respected contracting company in my town. They were troubleshooting site lighting by resetting the breaker a bunch of times between unhooking sections of the lighting. The building owner asked them to leave (I'd have done the same). My troubleshooting procedure was quite a bit different.
 
Or use an ohm meter as you isolate portions of the circuit..
I don't know is that more professional than a light bulb??
 
jjhoward said:
Or use an ohm meter as you isolate portions of the circuit..
I don't know is that more professional than a light bulb??
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Indeed it is. Anything besides tripping a breaker repeatedly until you find the fault. There are some breakers (expensive one's, old one's, etc.) that I shudder to trip even one time, since that might be the last time it will ever reset.

I have used a 120V fire alarm buzzer in the past as well if I'm working by myself and there's no one around to be disturbed.
 
I don't get it. Why the light bulb??
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For the famous expression, " Let there Be light !"

Hey wait a minute get in Line...

Consider it a short or open short on the ungrounded circuit in RMC(as the story went) if you inserted the lamp as described and switched the circuits (as they did) it complete the circuit the other (hopefully not effected) circuit will supplying good wattage through but be loading the bound that is the conduit.

I can't see how it done with a 2 wire, pre romex 2CwG. maybe I'll have to think aout it some more. :rolleyes:
 
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Problems that result in tripping breakers seem less troubling than those problems of no power here and there when all breakers are just fine!
 
jjhoward said:
Problems that result in tripping breakers seem less troubling than those problems of no power here and there when all breakers are just fine!
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You got that right. I can fix a tripping breaker (or intermittantly tripping breaker) problem pretty quickly, but the open circuit problems suck up some major time sometimes.
 
I have yet to replace our deceased amprobe T-4000. That Harris TS-90 looks sweet for the price. A tracer can save a ton of time and also makes you look like THE MAN.
 
jjhoward said:
I have yet to replace our deceased amprobe T-4000. That Harris TS-90 looks sweet for the price. A tracer can save a ton of time and also makes you look like THE MAN.
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The T-4000 is probably worth sending back to have fixed. Amprobe has fixed stuff for me for way less than I ever thought. I'd almost bet they're fixing their stuff at cost.
 
mdshunk said:
Anything besides tripping a breaker repeatedly until you find the fault.
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My SOP is to replace a breaker that anyone has reset more than a couple times. A tripped breaker is one of a very few things that I'll take a customer's word on. I never reset it to check. Continuity testing on dead & disconnected wiring usually accomplishes the same thing. I tell people if they continue resetting & tripping the breaker in a short circuit situation, they'll eventually blow the wire open. Then the repair can change from simple to rewiring.

I see the Amprobe T-4000 can locate faults in EMT. Do I understand the Harris TS-90 won't locate faults in BX or EMT?
 
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