New Light Trips Circuit Breaker

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I have just fitted a new external light which keeps tripping the circuit breaker.

It is a completely new installation - I have ran a cable straight from the fuse box to the light and a switch live circuit to an internal switch. I have checked (and even replaced) the wiring. To check everything I have removed the light fitting and wired it to a plug and this worked fine (no trip). I also took a short length of cable striaght from the fuse box to the light fitting (no switch) and this also tripped the breaker.

I can't understand why this is happening - as I mentioned it works fine when wired to a plug but not when it is connected directly to the fuse box.

Any advice is greatly appreciated.

 
Thanks guys for the quick responses.

  • The switch is wired okay - it did the same thing when I connected it directly to the fuse box with no switch.
  • I will knock up a circuit diagram and post this later
  • It is an RCD - with regards to the neutral bar this may be a possibility, There are two neutral bars and I have only tried one - I didn't realise that these would be different. What is the reason for this?
Many thanks again.

 
Back to very basic basics

RCD....electric goes in and electric comes out. If what comes out is less than what goes in by about 30 mA then the RCD goes all moody and cuts of the Lectric

If it is connected to the wrong Neutral bar then as far as the RCD is concerned electric has gone in AND NOT come out so it has tripped.

They are there to protect life...just saying

 
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+1 to the above, re connect it, bit with the neutral to the other neutral bar, and it will probably work fine.

One point, meant constructively: You said it tripped the "circuit breaker" which I read to mean an MCB, probably meaning a short circuit.  Had you said it was in fact the RCD tripping, the wrong neutral bar would have been more obvious. An accurate description of the problem would help.

 
+1 to the above, re connect it, bit with the neutral to the other neutral bar, and it will probably work fine.

One point, meant constructively: You said it tripped the "circuit breaker" which I read to mean an MCB, probably meaning a short circuit.  Had you said it was in fact the RCD tripping, the wrong neutral bar would have been more obvious. An accurate description of the problem would help.
I think someone's not happy because he didn't get the answer right. lol

 
It most probably will do. Just out of interest what were the IR results when you 'meggered' the drum before using it lol :)

 
Back to very basic basics

RCD....electric goes in and electric comes out. If what comes out is less than what goes in by about 30 mA then the RCD goes all moody and cuts of the Lectric

If it is connected to the wrong RCD then as far as the RCD is concerned electric has gone in AND NOT come out so it has tripped.

They are there to protect life...just saying
So ...let me get this ight .....you put the lectric in , the lectric out , in , out , shake it all about ... you do the Hokey Cokey and you trip the switch ...Sooooo thats what its all about !!!   :C .........................OOOooiiiih!!!!

Just saying !

 
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So ...let me get this ight .....you put the lectric in , the lectric out , in , out , shake it all about ... you do the Hokey Cokey and you trip the switch ...Sooooo thats what its all about !!! :C .........................OOOooiiiih!!!!

Just saying !
Yup, got it in one!Electric goes in, does its stuff, electric comes out....job done!

HOWEVER if the current transmogrifies itself into THE SMOKE then the electric stops coming out and it is busted, until such time as more smoke is fitted. Simple really....this is the bit that most people cannot grasp

 
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