No power to oven extractor

[Mark84]

I have recently had a new boiler fitted just above my kitchen grid type socket which feeds the washer, dishwasher, fridge and oven extractor fan.

after the boiler once installed there was a slight drip which landed on the grid socket. This resulted in it making a buzzing sound so I cut the power to the whole socket and let it dry out overnight. (The drip is now fixed and socket no longer makes a buzz)

Tonight I have powered the full grid socket back on and 3 out of the 4 appliances work.

I have checked the live and neutral coming out of the non working switch for the extractor fan and when I turn the switch on I get 240 volts. When I switch it off I get 0.

I have then tested at the fused switch socket above the extractor fan and have no power at all.

Is it possible the water has damaged the cable? Or is it more likely something has gone through the wire when the boiler was installed? The RCD in the fuse box or fuse has not tripped once throughout the whole boiler install.

I am confused as to what the problem is. It must be some kind of cable damage as 240v is definitely leaving the switch.

Thanks

Mark

 

[terryplumb]

On the supply side of the FCU ,what is the voltage ...
Line to earth
Line to neutral
With the grid switch on ,obviously.

 

[Mark84]

It’s 0 on both live to earth and live to neutral.

 

[terryplumb]

With the circuit isolated and proved dead, test for continuity from switch to fcu. On all three conductors. If the cable has been hit by a screw when boiler was fitted it may have severed the CPC and the neutral and the line may still be live. All three conductors can't be severed ,that would trip MCB for sure.

 

[Mark84]

How would I test the continuity at the fcu end? What would I connect the multimeter to as I only have one end of the wire? Or do I need to connect two wires together at the grid end with the power off and then test continuity at the fcu end on the two wires?