circuit breaker trouble

[michaelbratton]

i recently re wired a house and am at the comissioning stage. everything working apart from 1 lighting circuit. the original problem was that the circuit breaker and rcd protection were on and working fine. however as soon as a light was turned on the rcd would trip. this was however only when a globe was in a light. i split the circuit and found the middle light was on working fine so the problem was down the line.

so i went to a light further down and found that a neutral was loose. i re connected this. however whilst this was now not tripping the rcd, as soon as i tried the same thing with putting a globe in and turning on the circuit breaker was now tripping. and when trying to reset it was popping but staying on

i have inspected all the connections and followed the cable and there is no visible thing that would be causing this.

any help???????

 

[Reloadron]

What is a rcd? Would that be a standard circuit breaker? Have you tried swapping the breaker assuming everything else is wired correctly?

Ron

 

[canadaelk]

https://en.wikipedia.org/wiki/Residual-current_device similar to a GFI

 

[chuckey]

I have come across a case where ONE lampholder in a chandelier suffered from some form of chemical coating/attack? Anyway it had a low leakage resistance between it and the metal chandelier. You do not say whether they are SES or BC bulbs. In general it does not make sense. Without a neutral wire if there was leakage from the neutral of the bulb to the metalwork then even without a neutral wire being connected, when the circuit was switched on the current from the live would go through the bulb to the metalwork and trip the RCD.
Frank

 

[Reloadron]

Thanks for the education as to RCD and the link. So I guess I would be looking for leakage or a faulty RCD device.

Ron

 

[Zerotolerance]

Sounds to me like you have a grounding issue somewhere. Where the neutral is grounding out on something causing an unequal flow of return current. Could the drywallers have pierced one of the wires when installing it? I have seen this happen before and through pipes.

To properly rewire a house you have to remove drywall correct? I know you have to at least tack the romex every 3ft or so.

 

[filbo]

Where are you working MichaelBratton? I am from Australia so can only speak from my experience here.

Where have you looped your circuit, behind the switches or in the ceiling (ceiling roses or junction boxes)? Is it possible that you may have crossed a switched wire and a neutral? Have you overtightened and subsequently cracked a socket?

Have you completely rewired the house or have you used all or some of the old accessories? Have you pulled the cables in while removing the old cables (i.e., used the old wiring to pull the new cabling into place). Was the old installation in metal conduits...maybe rubber and cotton wound insulation (very old)?

If the circuitbreaker seems to be popping when you close it, it sounds as though it is closing onto a fault, but a resistive one, since it shouldn't close onto a fault at all (trip free mechanism!). It doesn't sound like an earth fault since the RCD isn't tripping now. Maybe tightening the loose neutral earlier bought this fault to light downstream.
Is the house occupied? Can you turn off the supply. What insulation resistance should you be getting...what reading are you in fact getting?

I am not just answering your questions with my questions, just trying to get you thinking along those lines. These are issues I have encountered in my work and a few of the causes.

Let us know how you go.

Best regards Phil

 

[squishy36]

To emphasize what others have said, if you have a GFI (RCD) tripping, you have either a hot to ground leakage or a neutral to ground leakage somewhere.