Vexing Electrical Problem

[Phil Thien]

I disconnected the hot and neutral at the breaker and took apart the pigtail in the bedroom light switch. That leaves me a wire, disconnected at either end, from the light box to the breaker box. I have some continuity between the ground and hot. I also have some continuity between the hot and ground going the other way. I can go down the line disconnecting switches, outlets and lights and confirm the continuity, the only thing that changes is the reading.

What kind of meter are you using?

[Pat Barry]

I disconnected the hot and neutral at the breaker and took apart the pigtail in the bedroom light switch. That leaves me a wire, disconnected at either end, from the light box to the breaker box. I have some continuity between the ground and hot. I also have some continuity between the hot and ground going the other way. I can go down the line disconnecting switches, outlets and lights and confirm the continuity, the only thing that changes is the reading.

I have strange behavior when I reconnect everything.

The breaker blows immediately if I switch either the fan or light in the bedroom on. This was the original problem.
The hall lights, dining room lights, foyer lights, and kitchen lights all can trip the breaker, but not immediately. This is weird. I flipped the hall light on and it tripped the breaker. I reset the breaker and the hall light didn't trip the breaker the next time I turned it on, but the foyer light did. I reset the breaker, turned the foyer light on and it didn't trip the breaker so I tried the hall and kitchen and it didn't trip the breaker either so I tried the dining room light and it did trip the breaker. It just goes 'round and 'round in a seemingly random pattern. Reset the breaker and one of the light switches will cause it to trip, but there is no telling which one will do it at any time. Also, if I reset the breaker and do nothing it will trip after a random period of time.

I quit.

I'll bet you a nickel that there is a wire pierced by a nail somewhere in the run. It probably was there from day 1 when the electrician installed the wiring and it finally caused a problem due to temperature change, and or breakdown. I think new wiring is the best fix unless you want to rip down the Sheetrock to confirm the failure. Given what you said about it being new construction I would insist on warranty replacement at no charge to you.

[Duane Meadows]

I agree with Pat, if it's new construction, let the contractor pull his hair out over it

[Dennis McDonaugh]

What kind of meter are you using?

It's a Fluke DVM.

[Tom Stenzel]

I remember decades ago when we had problems at work with communication cables we would use a time domain reflectometer to find where the problem was. I'd hate to think that you would need to those lengths to find a house wiring problem.

One time I got dragged into repairing a home intercom system in a newly constructed house. I don't think there was a cable anywhere that didn't have a staple sunk through it. A true nightmare to repair.

If the contractor is at fault he needs to be leaned on to make it right.

-Tom

[ray hampton]

I'm thinking this is going to be the fix, but it's not going to be easy because there is a floor in the attic above the laundry room (location of the breaker) and hall. All the interior walls are also filled with insulation.

is the insulation the matt type or pump-in type insulation ? your insulation could be forcing a wire to move in a hazard manner

[Phil Thien]

It's a Fluke DVM.

So if you have a leg from the load center to a box for a receptacle (for example), and with both ends detached you find continuity. And you also have a leg from that receptacle box to (for example) a box with a switch, and with both ends detached you also fine continuity. And if you have yet another leg (same as the other two) and you're finding continuity on THAT one, then I'd guess maybe you're using your fingers to hold the probes to the wires and the continuity is your body?

I can't imagine you're going to have multiple bad legs.

[John Lanciani]

So if you have a leg from the load center to a box for a receptacle (for example), and with both ends detached you find continuity. And you also have a leg from that receptacle box to (for example) a box with a switch, and with both ends detached you also fine continuity. And if you have yet another leg (same as the other two) and you're finding continuity on THAT one, then I'd guess maybe you're using your fingers to hold the probes to the wires and the continuity is your body?

I can't imagine you're going to have multiple bad legs.

+1. As someone who maintains and uses $100,000 or so of fairly sophisticated test equipment (electrical substation testing) I'm thinking that there is probably some user error creeping in here. I'd personally put everything back together, put a regular breaker in the panel, and measure current on the circuit with everything turned off (with the breaker on). Depending upon what model Fluke you're using you may already have what you need but you do need a fairly sensitive ammeter to test the circuit this way (a Fluke 289 for example will measure micro-amps) . If there is leakage it will be easily evident; if there is no leakage you've been chasing your tail.

[Dennis McDonaugh]

So if you have a leg from the load center to a box for a receptacle (for example), and with both ends detached you find continuity. And you also have a leg from that receptacle box to (for example) a box with a switch, and with both ends detached you also fine continuity. And if you have yet another leg (same as the other two) and you're finding continuity on THAT one, then I'd guess maybe you're using your fingers to hold the probes to the wires and the continuity is your body?

I can't imagine you're going to have multiple bad legs.

I have continuity both directions. I'm definitely sure I have an issue between the breaker box and the light switch box because there isn't anything there but the wire. It can't be more than 20' feet between the two. Then I have continuity somewhere down stream of the light switch box, but I don't know where. I know how to use a Ohmmeter. I was an electronics tech for 25 years in the Air Force and I'm using a high $$ Fluke meter with clip leads. I'm not an electrician however.

[Chuck Wintle]

+1. As someone who maintains and uses $100,000 or so of fairly sophisticated test equipment (electrical substation testing) I'm thinking that there is probably some user error creeping in here. I'd personally put everything back together, put a regular breaker in the panel, and measure current on the circuit with everything turned off (with the breaker on). Depending upon what model Fluke you're using you may already have what you need but you do need a fairly sensitive ammeter to test the circuit this way (a Fluke 289 for example will measure micro-amps) . If there is leakage it will be easily evident; if there is no leakage you've been chasing your tail.

I wonder if the OP ever had an electrician visit to see the problem. So many opinions and possible solutions but if the OP does not understand what is what then it cannot help. JMHO

[Dennis McDonaugh]

+1. As someone who maintains and uses $100,000 or so of fairly sophisticated test equipment (electrical substation testing) I'm thinking that there is probably some user error creeping in here. I'd personally put everything back together, put a regular breaker in the panel, and measure current on the circuit with everything turned off (with the breaker on). Depending upon what model Fluke you're using you may already have what you need but you do need a fairly sensitive ammeter to test the circuit this way (a Fluke 289 for example will measure micro-amps) . If there is leakage it will be easily evident; if there is no leakage you've been chasing your tail.

I'm done with it, whether its self-inflicted or not, I'm chasing my tail and will let the electrical contractor handle it.

[ray hampton]

I'm done with it, whether its self-inflicted or not, I'm chasing my tail and will let the electrical contractor handle it.

after your contractor solve the electrical problem will you tell us what the problem is/was

[Dennis McDonaugh]

after your contractor solve the electrical problem will you tell us what the problem is/was

Of course I will. Too many people have offered advice not to provide closure!

[Chris Padilla]

Of course I will. Too many people have offered advice not to provide closure!

Plus curiosity is just KILLING us as to the culprit here!

[Jim Koepke]

Then I have continuity somewhere down stream of the light switch box, but I don't know where.

My first guess would be a bulb in a light socket.

How many ohms your meter is reading tells the story. If it is in the 10-30 ohm range it may be a light. A bathroom fan motor may be higher. A high resistance could be pierced insulation. It may not be a problem until a little heat expands the wires and the resistance drops enough to open the breaker.

This could be something caused by an inexperienced sheet rocker.

jtk