Thermionic Idler wrote: ↑Wed Dec 08, 2021 10:39 am
RCD on the power outlet circuit began tripping out yesterday at about midday. We'd reset it, about 5 or 10 minutes would go by and then everything would go down again. It had gone out once before about a month or two back but with no repeat. With it being intermittent like that (rather than immediate) that made trying to track down the rogue appliance yesterday afternoon such fun.
Anyway, I think we managed to isolate it to something that shares a long power strip with my desktop computer, as on one occasion it tripped immediately on plugging that strip in. Currently I only have the essentials from that strip plugged in, and everything seems to be stable. My hunch is that it's the Wharfedale Active Diamond III's that I use for computer speakers - they have to be well over 30 years old by now, possibly a fault with the power transformer? I checked the plug and they are earthed, so there could well be a current-to-earth scenario occurring there.
Have it PAT tested. If you've a small independent electrical retailer nearby they will sometimes be able to do that. If the power cable is removable, it might be worth swapping that first (if PAT testing, the cable must also be checked).
Things that fail include the transformer (possible. especially if there's humidity about or it gets hot [check that with a thermometer/hand]), surge suppressor devices which can break down over time, Y2 capacitors etc. Testing needs to be carries out at full mains voltage for a class 1 device. Insulation testing is typically done at around 500VDC (ISTR).
So, if using a surge suppressor power strip or there are surge suppressors in the device, they can be suspect. Any Y2 caps (which typically go from L & N to PG) can also be suspect.
Your comments about the increasing frequency of the fault condition triggering the RCD also suggests slow degradation of the faulty component(s).
Another point is that RCDs themselves & your general electrical infrastructure can get wonky (technical term, that) over time and it may be worth getting an EICR test done for your abode, especially if nothing has been done for a while - testing RCDs is COMPLEX and requires special equipment - the little test button on them is next to useless/dangerous and tells you almost nothing except that the RCD will
eventually trip - the current/time curve for RCDs is very specific and can only be properly checked by some with a) the right kit and b) who knows how to use it!
(*) caveat. I am not a certified electrical engineer - we rent properties and have to have EICRs done from time to time. When done properly by a diligent electrician EICRs can be really informative. I have had brand new good manufacturer RCDs (bought from TLC & CEF) fail out-of-the-box, i.e. when a brand new installation is tested - the little button test makes it "pop" but a proper test with the right kit shows a complete failure of the current/time tests, i.e. it's dangerous to humans & animals.