S
stonejenson
Client's cooker/hob stopped working - he called his service plan chaps and they said the cooker and hob were fine, but it was the supply, so he should call an electrician.
I went round and it seemed like an obvious problem, the quite old 45A isolator had had a meltdown and fallen apart inside - he said it had been hard to switch for sometime. I put it down to old age, as the 40A mcb had not tripped, so I swapped the switch - all seemed well.
2 days later, and it had 'popped' while in use, so I went back. New cooker switch was fine, but the supply CPC had somehow jumped out of it's connection, and I'm pretty good with getting my wires in tight, so thought it was odd, and why would that have caused the mcb to trip? (No RCD protection to circuit)
I took the oven out, it was fed from a socket via 13A plug, spur from the hob supply - I checked from consumer unit to switch, to cooker connection point - worst result was over 400Megs N to E.
I checked each appliance L-E and N-E, both fine. Impossible to test any L-N short out, as cooker has a clock, and hob is all touch controlled, so will have an internal circuit which will not give a good result anyway.
I reset mcb, zs result was fine.
I turned off, put it all back and it turned on ok.
I put it down to me possibly messing up the CPC wiring to begin with, and walked away a little confused, but pretty sure it was caused by the appliances themselves.
The next morning client calls and said it's tripped out again - AND NEITHER THE HOB OR COOKER WERE IN USE !?!?!?!?!
He's gone on holiday now for 10 days, so can't go back and check, but just thought about putting clamp meter over supply to see if there was any odd current draw when appliances were not on. I don't trust the hob's internal circuitry myself - but just wondered if anyone else had had a similar issue?
I went round and it seemed like an obvious problem, the quite old 45A isolator had had a meltdown and fallen apart inside - he said it had been hard to switch for sometime. I put it down to old age, as the 40A mcb had not tripped, so I swapped the switch - all seemed well.
2 days later, and it had 'popped' while in use, so I went back. New cooker switch was fine, but the supply CPC had somehow jumped out of it's connection, and I'm pretty good with getting my wires in tight, so thought it was odd, and why would that have caused the mcb to trip? (No RCD protection to circuit)
I took the oven out, it was fed from a socket via 13A plug, spur from the hob supply - I checked from consumer unit to switch, to cooker connection point - worst result was over 400Megs N to E.
I checked each appliance L-E and N-E, both fine. Impossible to test any L-N short out, as cooker has a clock, and hob is all touch controlled, so will have an internal circuit which will not give a good result anyway.
I reset mcb, zs result was fine.
I turned off, put it all back and it turned on ok.
I put it down to me possibly messing up the CPC wiring to begin with, and walked away a little confused, but pretty sure it was caused by the appliances themselves.
The next morning client calls and said it's tripped out again - AND NEITHER THE HOB OR COOKER WERE IN USE !?!?!?!?!
He's gone on holiday now for 10 days, so can't go back and check, but just thought about putting clamp meter over supply to see if there was any odd current draw when appliances were not on. I don't trust the hob's internal circuitry myself - but just wondered if anyone else had had a similar issue?
