Hi guys (and girls)
Have a job for a long term customer, finding a pretty awkward fault. I'm almost to the point where I'm a bit stumped. Generally speaking IR testing, RCD testing and experience hasn't let me down in the past and I've found plenty of faults other 'electricians' haven't.
Symptoms are:
Loud bang, possibly from kitchen area, happens around once every 3-4 weeks. Downstairs RFC RCBO trips out. This covers all sockets downstairs, bar 3. It has apparently happened twice overnight, when no appliances are being used - customer has come downstairs to find circuit off. This has been ongoing for a few months now. The consumer unit is at the other end of the house to the kitchen.
Testing so far:
All loads disconnected Line-Earth, Line-Neutral and Neutral-Earth all reading over 70Mohm.
All loads connected L&N connected together tested to Earth - 5.5Mohm
I thought I found it when I found an old fridge with a very low resistance line to earth. Sadly not. The fridge has been replaced.
Nearly new Hager consumer unit (fitted last year) RCBO ramp tested. All ok.
Conclusion:
The customer is a liar! Highly unlikely in this case.
or
Appliance is causing the issue. What would cause this at any time of the day randomly when nothing is operating though? How to confirm this without a scattergun approach of renewing appliances/plugging them in to different circuits?
or
Something is happening to the fixed wiring once a month to case a 'bang' and a fault. Seems highly unlikely to me with the IR readings I'm getting.
Anybody got anything to add? Hopefully I'm missing something blindingly obvious here! One downside of fitting RCBO boards is I don't actually know whether or not I'm probably looking for a L-N or a L-E fault, which is slightly unhelpful.
Cheers
Have a job for a long term customer, finding a pretty awkward fault. I'm almost to the point where I'm a bit stumped. Generally speaking IR testing, RCD testing and experience hasn't let me down in the past and I've found plenty of faults other 'electricians' haven't.
Symptoms are:
Loud bang, possibly from kitchen area, happens around once every 3-4 weeks. Downstairs RFC RCBO trips out. This covers all sockets downstairs, bar 3. It has apparently happened twice overnight, when no appliances are being used - customer has come downstairs to find circuit off. This has been ongoing for a few months now. The consumer unit is at the other end of the house to the kitchen.
Testing so far:
All loads disconnected Line-Earth, Line-Neutral and Neutral-Earth all reading over 70Mohm.
All loads connected L&N connected together tested to Earth - 5.5Mohm
I thought I found it when I found an old fridge with a very low resistance line to earth. Sadly not. The fridge has been replaced.
Nearly new Hager consumer unit (fitted last year) RCBO ramp tested. All ok.
Conclusion:
The customer is a liar! Highly unlikely in this case.
or
Appliance is causing the issue. What would cause this at any time of the day randomly when nothing is operating though? How to confirm this without a scattergun approach of renewing appliances/plugging them in to different circuits?
or
Something is happening to the fixed wiring once a month to case a 'bang' and a fault. Seems highly unlikely to me with the IR readings I'm getting.
Anybody got anything to add? Hopefully I'm missing something blindingly obvious here! One downside of fitting RCBO boards is I don't actually know whether or not I'm probably looking for a L-N or a L-E fault, which is slightly unhelpful.
Cheers
