Tripping 6amp breaker

[PB1]

A customer of mine had the same problem, tripping the breaker after an hour. I spent a couple of hours testing IR and used a clamp meter as he switched the lights on one by one. Current crept up to about 4.5 amps with all lights on. Kept the clamp meter in place but it didn't trip while I was there. He was having lots of work done with a new bedroom and bathroom over the garage. The joiner had been putting some plywood down to make a temporary floor in this area. The fault was eventually found by the customer himself after the circuit tripped while he was moving the boards in the working area, and it was due to a cable that had been nipped by the board. I presume this must have breached the insulation to some extent. Anyway it was fixed by cutting out the bad bit of cable. Not quite sure what was happening in the hour leading up to the tripping though. Could the cable be warming up over this time, to cause some expansion of the cable and reduction in resistance of the insulation between line and neutral? Good luck with finding the problem!

 

[SirKit Breaker]

If it int overloaded, then have a look at the physical condition of the breaker. You will need to take it out of the board to look very closely at it. I had a similar problem a few years ago, and the breaker had a very fine crack in it.

Also is there another breaker that you can put the offending circuit into, to see if the fault moves across?

Cheers........Howard

 

[eco-tech]

Grrrrrrrrrrrrrrrrrrrrrr

Thought I found it...............

Then when I put back the last light bulb in, it tripped after 5 mins.

The circuits was fine for 6 hours before I put the bulb back in.

1st thing this morning it tripped after 1 hour.

Do you think it could be this circuit that I put the bulb in (the house is damp)

 

[eco-tech]

Changed the breaker and checked all connections in fittings etc.

 

[eco-tech]

mmmmmmmmmmmmm could be the only rose I not looked at (hence last one on the circuit) but would it still trip if isolated at switch (2 way)

 

[telectrix]

nobody has yet mentioned the fact that if the MCB is tripping after about 1 hour, it could be a 50% overload. say around 9A. the MCB will stand this for so long, then trip. clamp meter the circuit at the CU and switch all the lights on, see what current is drawn.

 

[Richard Burns]

Have you checked the light bulb, are the contacts dirty is the lamp old? simple things sometimes, but not really sure in this case.

 

[Richard Burns]

nobody has yet mentioned the fact that if the MCB is tripping after about 1 hour, it could be a 50% overload. say around 9A. the MCB will stand this for so long, then trip. clamp meter the circuit at the CU and switch all the lights on, see what current is drawn.

Think I may have mentioned that on post 21! Though I did say 8A not 9A

 

[SPARTYKUS]

The plot thickens!

Was there any tell tale signs of damage to the MCB you took out.

Good thread lots of great advice

 

[eco-tech]

It's an old fitting but new bulb.

This one has done me in.

Like I say it was fine for 6 hours then after about 1 hour of me connecting this last bulb in, it tripped.

 

[eco-tech]

No the mcb was fine but kept new one in.

 

[SPARTYKUS]

Irrelevant question but wat make is the mcb?



Just wondering if its a dodgy recall electrium one!

 

[eco-tech]

Also trips with just one light on so not a overload problem me not thinks !

 

[eco-tech]

think it was merlin

 

[eco-tech]

aghhhhhhhhhhhhhhhhhhhhhhhhAGHHHHHHHHHHHHHHHHHHHHHHH lol