Breaker tripping

[highspark]

Lads odd fault.

Breaker trips 20 mins-1 hour after being switched back on. 32 amp ring, old wylex board with push fit circuit breaker. Wiring is a mess. Ring is for sockets. It has exterior lights, alarm, boiler , attic lights, pond pump and fountain - all from jb's in attic - thoughts definate overload. Problem is I've unplugged everything and it's still tripping. There's a load bang in the attic everytime it trips. Any thoughts?

 

[Rockingit]

How confident are you that everything is indeed, 'off'. Have you clamped the circuit at the DB to actually check it's drawing 0.00A? My guess is either rain in an outside light or rodents - I once spent hours chasing a popping light circuit and it was a dead spider inside the pendant!!

 

[highspark]

I've clamped it and yes it's all definitely off.

Why the he'll is it lasting for 3 hours then popping..... With everything unplugged!!!!!

For 3 hours it's ok the bang on time it's off!

I feel stupid not isolating it now. I've done all IR's, clamp metered it and inspected jb,s and cable where I can! But still nothing!

 

[GLENNSPARK]

I've clamped it and yes it's all definitely off.

Why the he'll is it lasting for 3 hours then popping..... With everything unplugged!!!!!

For 3 hours it's ok the bang on time it's off!

I feel stupid not isolating it now. I've done all IR's, clamp metered it and inspected jb,s and cable where I can! But still nothing!

you say "bang on 3 hours".....like somethings timed or summat but you also say you clamped it and its definately off?.....what type of heating system is here? Y plan? salamander box?..so like you dont have any current draw .....until the y plan operates that is (which wont use owt much anyway) and.......

 

[hyperloop]

Ive had a similar scenario in the end had to test each section of the ring to find - a bit long winded but better than trying something and hoping for the best each time then getting the dreaded call.....

 

[Rockingit]

Just a thought - have you disconnected the circuit directly at the breaker then left the breaker on? Sounds silly, but at least it would discount the mcb itself.

another thought - is this on a split board? might have a shared neutral issue

 

[Octopus]

I's split the ring in half,fit a 16A breaker and leave 1 half connected and see what happens, then try the other half.

Sounds like a "nice" fault to have - can the customer afford your time?

I have to admit that the "bang" does sound interesting!

 

[highspark]

I split it today where I thought was tge centre of the ring only one breaker tripped but it seems to have taken out more than half of the circuit. It's only a 4 way board no spare was etc. It's a bloody nightmare. At first customer was getting 20 mins then it was tripping. Now he's getting 3 hours - since I've opened up jb's etc. My problem is what the hell is allowing it to be on for 3 hours and then tripping if everything is unplugged and it's not an overload!

 

[hyperloop]

dont forget tripping will take time if theres a IR fault not serious enough to cause instant tripping - check out operating times in 7671. And the fault is constant so will take same time every time to occur. Must trace it through testing each leg of the ring.

 

[UKMeterman]

Hi,
If it is tripping after 3 hours on THERMAL overload and this is 32A breaker there is a lot of power going somewhere! I would suspect some kind of arc over instead, causing a short.

 

[Rockingit]

Do you know anyone with a thermal camera that you could beg/borrow/rent/steal? That energy has to be dissipating itself as heat, so it probably wouldn't take long to track down with an IR scope, even a 'cheap' one.

 

[highspark]

Hi lads eventually found it on Thursday. Had to rip up laminate flooring got under to find spur after spur from jb's ( far from a ring ). Was a nightmare to test. Literally had to dissect each jb and test individually. Eventually located cable going under joists.

The fault was this..... Bungalow was built on brick raising it from floor/ground incase of flooding. Anyhow the wooden joistswhere built on brick for support and some sections had been wedged up by slate to get level. Over the years some of these slates had cracked/broken away so joists where dropping and trapping cable. Anyhow when someone walked in that area it was pressing on the cable and shorting out. Cable was destroyed, fire damaged etc.

Just shows the strange and hard faults to find!

 

[Rampage]

At least you found it!

 

[Hawk81]

Glad you found it

 

[Engineer54]

As above, ...and ''Thanks'' for coming back and letting us know the outcome!! Often to many threads just die with no conclusion or feed back from then initial OP!!

 

[Short Circuit]

Yep, agree with E54, Well done HighSpark, hope your customer is happy now too , or until they receive the bill, you must've spent ages looking for that fault! And its good to get the result back on here! Only one thing missing.. Photos!

 

[highspark]

Honestly lads absolute nightmare fault. Will never forget it! The loud popping noise was actually vibrations from the fault. It was so loud it sounded like it was in the attic.

I actually felt stupid not finding it but even the best spark would have struggled here. You live and learn hey!!! When you go to this kind of fault you expect recent work/activity to have been taking place. In this case there was non.

Will get pics next time. Thanks for the help lads. Possibly stopped an electrical fire here just shows how important mcb's and RCD's etc are.

 

[MarkieSparkie]

Well done Highspark and thanks for the feedback on the actual fault, much appreciated.

 

[malcolmsanford]

Hi lads eventually found it on Thursday. Had to rip up laminate flooring got under to find spur after spur from jb's ( far from a ring ). Was a nightmare to test. Literally had to dissect each jb and test individually. Eventually located cable going under joists.

The fault was this..... Bungalow was built on brick raising it from floor/ground incase of flooding. Anyhow the wooden joistswhere built on brick for support and some sections had been wedged up by slate to get level. Over the years some of these slates had cracked/broken away so joists where dropping and trapping cable. Anyhow when someone walked in that area it was pressing on the cable and shorting out. Cable was destroyed, fire damaged etc.

Just shows the strange and hard faults to find!

Are they going to do anything concerning the dropping?