hi weevilward
had a similar issue turned out to be a wine fridge some years ago, TT system everything on one RCD unit. would not be so bad if it was not in the cellar, every time we tested the circuit we unplugged the fridge to plug in lead light, found a problem on a ring short caused by a mouse, repaired tested time I got home phone call gone again, went back showed house keeper readings on meter IR testing circuit all clear.
anyway customer had all CB's replaced with RCBO units for each circuit & when it went again called me before turning on the RCBO, went in new wine fridge 3 months old causing issue. Maytag replaced no questions asked, did not help client with approximately 4 days of work caused by the fridge.
earth leakage meter very good used one of those a few times very helpful if you can turn on appliances whilst watching the readings.
have also had another fault about 10 years ago TT system same again 30ma trip on mains, IR tested whole house after I managed to take out all of the Neon indicated extension leads must have been 20-25 leads in the house, sh..t loads of electronics plugged in. spent all day on it IR tested could not locate, turned system on again plugged in & RCD down after 10-15 seconds, owner well it must be on a circuit I stripped down the conservatory, kitchen, lounge, heating, immersion, shower. each time I turned the system on I used hoover on each socket circuit & did not matter which one, owner did not believe me thought I was having him on that it was sheer over load of the RCD unit (30ma).
mentioned I would change board agreed price as I had already undertaken all of the testing on the whole house in that day & had results, agreed deduction on my days wages against fuse box change picked my money up next day got phone call my mate will change for less than you.
I lost it & called him c...t, told him good luck with testing his f.....king house, as I would not give him my notes as he did not want to pay for them.
