Very Infrequent RCD Trip

John.G

Single RCD (whole house) trips about every 18 months or so, two or three times with a interval of ~ 1 hour between trips, at night only, it resets immediately after each trip. The only items that start/stop during the night are a Fridge & a Fridge/Freezer, both are on plugs which I unplug after the first trip but still get another trip or two, then nothing for another 18 months or so or even longer. Obviously one would think it has to be something internal in my housr or a external socket fed from my consumer unit.

If not, is there any conceivable way that something external and "nothing" to do with my house is causing these infrequent trips??

I think its a TNCS system but there is a earth rod in the garage.

10-10-20

Hi John, is there any relation between the weather and the tripping that you know of? I noticed that mine was tripping on wet days when the rain was coming from the South - lead me to find a South facing external wall light on which had water ingress.

DublinDilbert

Something causing it, could be anything. Often its moisture related, fridge could have condensate getting where it shouldn't. Could be a slug getting into a junction box, if not sealed off (have seen it before)

If not too many circuits have the mcbs changed to rcbos, atleast this should narrow down the problem

John.G

https://www.boards.ie/discussion/comment/123941129#Comment_123941129

NO, it has occured in very dry conditions and some moderately wet conditions, no pattern to it.

John.G

https://www.boards.ie/discussion/comment/123941171#Comment_123941171

Fridges would normally be my prime suspects but both were/are unplugged after the first trip but still get one or two more trips after this.

smuggler.ie

Not a spark

moisture build-up/condensation within installation/tool/appliance might remain within for long time, even over several dry days. its "damp to touch", if that makes sense.
Could that be a factor?


Appliances/tools in unheated workshop/shed? if so
Same RCD cover workshop/shed outlets?
What RCD is installed?
Edit: How many circuits protected by that RCD ? hint: to many devices/circuits on single RDC

Q for sparks:
What RCD/RCBO should be installed/recommended for residentials: C or B , 32 or 40 ?
Thank you

John.G

I may and only may have found the culprit. It hadn't tripped any other night after my original posts but I inspected (again) my 3 outside sockets, one, and quite awkward to get at, had the wires twisted together even though the insulation looked OK. I then used one of my 30 year old highly sophisticated test plugs, and plugged the 6.2k ohm 37mA one into the socket to ensure the RCD was operating correctly. I then plugged in the 10.9k ohm 22mA one into the socket, no trip, but left it in for a few days/night, and on the 5th DAY at 1700 hrs the RCD tripped, of course this could have been due to any small accumulated added leakage of ~ 13mA tripping the RCD at 35mA, I then immediately removed the test plug, no more trips. I then cut the suspect outside socket tails back a little and separated the wires. I then plugged the 22mA test plug back in and had no further trips over the next 5 days or so, removed the test plug.

Trip Test Plugs.jpg