Light blowing fuse

[ted1234]

Around 6 weeks ago ago the fuse blew for my downstairs lights, replaced the fuse wire.
6 weeks later it's gone again, this time I have narrowed it down to our backroom light.
I disconnected our lighting fitting (has integral fan) because I thought that was at fault. (still blowing fuses)
So tonight I just connected a bulb holder and bulb and thought all was good..until about 20 mins later when the fuse blew again!
So at the moment I have completely disconected the wire and turned the switch on, this has been on for over an hour now and the fuse has not blown.
(power to the ceiling rose)
I am sure if I connect the bulb holder again it will blow.
Any ideas much appreciated.
(the other thing I don't get is why it doesn't always blow straight away ?)
Thanks in advance Ted

 

[ted1234]

An update,,, its just blown again! Grrr.
So it doesn't blow straight away ??
If the lighting circuit is ON but the switch for that particular light is off (as it has been all day it doesn't blow)
bearing in mind that the wire is completely disconnected at the ceiling.
Regards Ted

 

[bernardgreen]

The fault might be a damaged cable trapped under a floor board.

Walking on that floor board presses on the damaged cable and creates a short circuit.

 

[Jackrae]

Logic suggests you have a cable defect between the light switch and the ceiling rose. I would suggest that a "slow" fault (such as you have) is potentially more dangerous than a "fast" one (blows the fuse instantly) since there could be a source of extensive local heating ongoing.

 

[ted1234]

Thanks for the replies.
My son is convinced that when it blew just now it came from under the bathroom floor.
I guess I know what am I am doing this weekend

Thanks again......Ted

 

[ted1234]

OK, So I couldn't wait for the weekend
This is what I found under the floor, not sure what happened ?
The wire goes through a joist but was not snagged in any way and the hole through which the wire passes is a lot larger than the wire itself ?
Thanks again for the input..... Ted

Wire

• ted1234
• 13 Mar 2014
• 1

Looks like its been 'nibbled' at to me?

 

[EFLImpudence]

Meeces.

 

[JohnW2]

I agree - definitely rodents. Here's my one, caught before any of the conductors actually touched:

Untitled

• JohnW2
• 24 Nov 2012
• 7

Kind Regards, John