Upstairs lighting circuit keeps tripping

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We have 3 bedrooms, bathroom and a seperate toilet, the lights in the bedrooms and the bathroom work ok but when you go to switch the toilet light on the breaker always trips out, i replaced the ceiling rose and pull cord switch and have also replaced the wiring from toilet switch to light switch and from toilet light to the bathroom light but the problem still persists, any ideas.
 
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Did the problem exist before you replaced the ceiling rose et al, or has it started recently?

Photographs of your ceiling rose and switch wiring would be helpful - though make sure the circuit is dead before doing so.
 
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Can you tell us what is tripping? Is it an MCB or an RCD?

An RCD will have a tes button on it.
 
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Have you recently done any other electrical work on this circuit?

Or have you done any diy work like drilling holes, or going up into the loft?
 
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It stopped working a while ago, i changed the ceiling rose as it looked old and tired, the problem persisted so i then went to the pull cord switch which i replaced, it was still tripping mcb as soon as you pull the cord switch so i thought there might be a problem with the wiriing coming from the bathroom light so i replaced all of that and it still keeps tripping, i'm a bit baffled especially as all the other lights seem to be working when you switch them on, its tripping an mcb on the consumer for the upstairs lighting, by the way i'm a plumber with basic electrical knowledge.
 
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It stopped working a while ago, i changed the ceiling rose as it looked old and tired, the problem persisted so i then went to the pull cord switch which i replaced, it was still tripping mcb as soon as you pull the cord switch so i thought there might be a problem with the wiriing coming from the bathroom light so i replaced all of that and it still keeps tripping, i'm a bit baffled especially as all the other lights seem to be working when you switch them on, its tripping an mcb on the consumer for the upstairs lighting, by the way i'm a plumber with basic electrical knowledge.

But did it trip before you changed the rose, or did it just not work?
 
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It was tripping before i done any of the work, its been like it for a while, its my mums house and she has been without a toilet light for a while because it kept tripping, i have only just got round to looking at it as i have been busy.
 
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Could be many things.

An incorrectly wired light or switch could cause this, but since it was ok at first then it's probably not that.

A damaged cable is possible, it could have got damaged or crushed in the loft, if there is one. Or even drilled through.
 
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Its just an MCB (not RCD) that protects the upstairs lighting circuit, what i can't work out is why the bedroom and bathroom lights are working ok when you switch them on, its just as soon as you switch that toilet light on it trips the mcb, if you leave it of then everything is fine, also i think the toilet light is the last one on that circuit as all its wiring comes from the bathroom light fitting.
 
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Also check for rodent damage to the cable in the loft, switch off the power first as there could be live exposed copper and touching it could be fatal.
 
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If there was any cable damage from the bathroom light back to the consumer unit i'm guessing it would trip but it doesn't and like i say the bathroom and bedroom lights work ok so i guess the cable is ok, however like i just said the toilet light is wired from the bathroom ceiling rose and is the last on thet circuit and i have replaced all of that so its bugging me.
 
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If a damaged cable was causing the fault it probably be somewhere between the toilet light and the toilet switch.

Is there an extractor fan in the toilet?
 
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I've changed all the cable from the bathroom ceiling rose to the toilet so that is all new now, could you just verify the wiring for me.

The bathroom ceiling rose goes to the toilet light fitting and then to the toilet light switch as follows-

Earth from bathroom ceiling rose to toilet light fitting to toilet light switch.
Live from bathroom ceiling rose Loop in to live on toilet light fitting to com on pull cord switch.
Neutral from bathroom ceiling rose (it says flex but its where the other neutrals are) to neutral on toilet light fitting to L1 on pull cord two way switch.

L2 is left empty for one way option on the pull cord switch.
 
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I've changed all the cable from the bathroom ceiling rose to the toilet so that is all new now, could you just verify the wiring for me.

The bathroom ceiling rose goes to the toilet light fitting and then to the toilet light switch as follows-

Earth from bathroom ceiling rose to toilet light fitting to toilet light switch.
Live from bathroom ceiling rose Loop in to live on toilet light fitting to com on pull cord switch.
Neutral from bathroom ceiling rose (it says flex but its where the other neutrals are) to neutral on toilet light fitting to L1 on pull cord two way switch.

L2 is left empty for one way option on the pull cord switch.

That is wired up wrong, and will trip the mcb.

You have a 2 core and earth cable from bathroom to the toilet light, and a 2 core and earth from the toilet light to the switch.

With the power off, at the toilet light connect the two browns (or reds) in a connector on their own. Connect the blue (or black) from the bathroom to the N terminal of the toilet light fitting. Connect the blue (or black) from the switch cable to the L terminal of the toilet light fitting. This blue should be sleeved with brown (or red) sleeving.

The blue (or black) at the switch should also be sleeved .

Make sure all earths are connected to all earth terminals. Bare earth wires should be sleeved with green and yellow sleeving.
 
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So the live from the toilet light fitting goes to the bathroom ceiling rose loop in, is that correct?.

With the power off, at the toilet light connect the two browns (or reds) in a connector on their own

Not sure what you mean, are these not needed.

What goes in to L1 on the 2 way pull cord switch.
 

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