Kitchen MCB Fault

[Rolyberkin]

Hi

I have an mcb which is on my kitchen circuit which is tripping, the installation is about three years old and although I undertook the installation it was was checked and signed off by a local electrical company for building regulations when I built an extension. it has a split load board of which only one side has an RCD.

The installation has been trouble free until last night when the mcb blew taking out the RCD, it reset and stayed on for about an hour when it blew again, it now will not reset, I have visually checked all plug fronts and connections and there is no obvious sign of mechanical damage or broken cable insulation. I have continuity on both neutral and live circuits from the consumer unit. The mcb is 32amp. The circuit normally has two freezers, a cooker hood,microwave and TV on it.

I have removed all appliances and removed all fused spurs from the ring main and disconnected an outside plug from this circuit. With nothing on the mcb keeps tripping.

There has been no D.I.Y in the house and the only thing out of the ordinary was the use of a battery charger on another circuit (about this time was when the mcb first blew) although the ring main where this was used is self contained and as I see it as coincidence, I have also used a 110v diesel fuel pump on the circuit which is tripping, I only say this as had a thermal overload protector which regularly cut in and out, could this have had a detrimental effect on a cable somewhere?

Is there any more I can do or check prior to the electrician being called?

Many thanks for any advice.

Regards

KB

 

[Spark123]

Trying to reset the MCB continuously is a bad idea, it may well now be U/S. The correct way to continue would be to call in a spark to do an insulation test of the wiring.
I'm assuming you were using a tool type transformer for the pump! If it isn't plugged in then it won't be this causing the problem, more likely some sort of mechanical damage.

 

[PrenticeBoyofDerry]

If you have not got an insulation resistance meter, unplug all appliances and equipment, isolate circuit and try checking continuity again across all the conductors without using a link on conductor ends at the CU. This could show up a short somewhere.

 

[Rolyberkin]

Hi

Had an electrician (well in fact two!) in and they performed all tests and found a broken earth between two sockets, the insulation tests are fine over the effected piece of cable and the ring main in general.

Is this an issue safety wise, both sockets are covered by an earth cable but to stop the MCB tripping the faulty earth cable has been terminated in each back box. Do I need to replace the cable or can I continue to use this two way earth 'radial' circuit?

Many thanks for replies thus far.

 

[PrenticeBoyofDerry]

If the circuit is ring final, the ring must be continuous, so the length that has been broken should be replaced.