Circuit breaker trips frequently even with out load

[newisfun]

Hi All
I have a typical problem.One of the c.breaker(16a) trips quite often. The problem started lately with out any new appliances installed.I tried disconnected all the appliances one by one, but still with out load it still trips.This is a power ring for kitchen(with combi gas boiler) and bedroom. 7 months ago installed power shower 8.5kv(dedicated 10mm2 cable run till CU), but no complaints all these days for it. Help is much appreciated. (I am an amature DIY enthuiast)

 

[plugwash]

intermittent faults are always the worst kind.

open every socket (with the power to the cuircuit off of course) and inspect the wiring. If gromets are missing then fit them. If insulation looks in any way damaged cover it with sleeving (of appropriate color). If earths are unsleeved or poorly sleeved (e.g. some sleeve there but lots of bare copper too) sleeve them.

also 16A is very low for a kitchen supply. maybe the breaker is failing due to repeated overloading in the past (what appliances do you normally use on this cuircuit?).

 

[newisfun]

Hi Plugwash

Thanks for the suggestion. I will come back once I do it.

I have connected chest freezer ,2 fridges, microwave, combi boiler, dishwasher, washing machine, toaster, mixer, calling bell(wireless, but instrument plugged into the socket), TV. This system was running for the last 8 months. All of a sudden I got this problem developed. I smelt 20 days ego some burning smell. Couldnt make out were it was. Next, the MCB started tripping occasionally(only this MCB out of 4 in CU), but now its more frequent, some times with in a hour. Now I noticed when I opened CU, the Bus Bar sleeve is burnt(That could be the reason on that day u smelt some thing burning).

Now the situation is, all the appliances and instruments are unplugged, but still the circuit is tripping.

Its a nightmare as of now.

Cheers

 

[newisfun]

Hi Plugwash

Do you suggest I should change MCB itself ?

Cheers

 

[crystal ball]

Sounds like a fault in the circuit wiring, do you ever have mice, they enjoy the taste of pvc cables

 

[newisfun]

Yes we noticed the activity some time ago. But, if mice have enjoyed the pvc, how should it effect the circuit with a delay in tripping.

My understanding is either it should be an open circuit or a short circuit, but in this case the MCB is tripping after a delay of 1 or 2 hours after being switched on. And also I can see a spark emerging on the first switch-on. Then may be second or third time I can see the MCB can be pushed-on.

I have a feeling, looks like energy is accumulated some where on the circuit once the circuit is ON, then after some time DO NOT KNOW what, it trips off may be of over load.

May be prolonged overload might have made the MCB mechanism to giveup before the threshold.(This is only my guess, Please correct me if its wrong)

Cheers

 

[crystal ball]

I have seen faults caused by mouse activity with all kinds of delayed tripping, one case was only when it rained, the roof leaked and the drips hit the cable right at the point whre the insulation was damaged, I think it may be time to lift a few floorboards

 

[Johnny101]

Hi newisfun, are you saying that you can see a spark inside or coming from the MCB?

 

[newisfun]

Hi

The spark seems to be originating from the side/ rear of this MCB, as I try to flick it up. But after couple of flicks, no sparks and its switched on. Its as if the charge held in it is being discharged at the frist instance. I carefully unplugged/opened all the sockets and closed them back safely, but in vain.

But I observed there is a "doob" sound emerging from the boiler bottom and eventually circuit trips. Non of the other appliances are making this sort of sound.

Could there be a problem with the coils in the Combi Boiler?

or Could there be problem with the MCB built in components(coils etc)

And I have carefully checked at the vulnerable points for short circuits by water contacts. No scope for such a senario, but will it matter for a earth wire which is in contact with a moist cold water copper pipe.Please suggest.

Any help in this area is much appreciated.

Cheers

 

[Johnny101]

Have you got antoher 16A breaker? If so, and please proceed with great care, you could rewire the circuit you are having problems with, into the other 16A breaker to see if the MCB is faulty although it is rare these go wrong. If you are unsure what you are doing to do not do this. I presume you don't have an insulation resistance tester?

Also what type of breaker have you got - Type B?

 

[newisfun]

I have got one more 16a mcb. I will try exchanging, instead of buying a new one at this stage.I do not have a tester.

Looks like I got Type 2 M6-proteus MCB

 

[newisfun]

I tried shifting the circuit on to the other 16a MCB. Now it is clear the problem is in this circuit not the MCB. Even the replaced MCB is tripping with sparks.

 

[Johnny101]

Time to call an electrician

 

[newisfun]

Cool

I just had my share of luck, after considerable struggle and with help of forum members who were very helpfull through out.

Crystal Ball guess was write. The boiler wall mounted in the kitchen which is near to the sink. Some time ago, I had a plumbing leak from the sink overflow.The water keeps dripping down on the floor along side of the wall were the wires are running to the main junction and the boiler point. I am not sure were the inslutation has got damaged, but seems to have in contact with the moist area.

I isolated these wires from the main junction and the boiler point and
by-passed with a 13A extension cable to just check. Its working as of now.

I even made sure there is no more plumbing leak.

So no more DRIPPING , hence no more TRIPPING.

Thanks all guys for sharing your expertise and bailing me out from ending up paying huge bills.

Thanks once again

Cheers

 

[newisfun]

Oh Noo.. Looks like I still have problem. But the problem is not that worst as earlier. The MCB can with stand for more than 6 hours and then trips. Now I have no idea what to do.