Cooker DP switch tripping RCD

[JohnW2]

Its probably vaguely possible, opening the neutral first / closing the live first will result in all the wiring of the appliance being at 240v with respect to earth instead of just that on the live side for the short time it takes the other pole to close. Not normally a problem but if there was a high resistance fault on the neutral side to earth then you could get RCD trip if the poles closed in the wrong order.

That, in itself, would not cause the RCD to operate. Immediately the neutral contacts open, no current will flow through either L or N sides of the RCD, even if the L contacts remain closed (hence no imbalance/trip) - unless, as discussed, there is a capacitive path to earth (lower impedance from N than from L).

Kind Regards, John

 

[dannyboi2003]

Mine used to do exactly the same, changed the switch and it solved the problem. No reason electrically why it would trip the RCD but it did, gremlins!

 

[JohnW2]

Mine used to do exactly the same, changed the switch and it solved the problem. No reason electrically why it would trip the RCD but it did, gremlins!

Yes, I've also heard of it working for people in the past, even though there is no 'obvious' electrical explanation. Of course, if/when that does happen, there must be an electrical explanation and a few possibilities have been speculated about here. A combination of an N-E fault and non-simultaneous closure of switch contacts, or the consequence of arcing (and capacitive paths) seem the two most likely contenders, but who knows?!

Kind Regards, John

 

[Fidget7]

After the first few times it happened, as the fault was intermittent, I tried to see if I could 'make' it happen with the technique at which the switch was operated. The only thing that made it trip was to toggle the switch on/off several times quickly, though I didn't attribute that as the cause as it seemed to me that doing that with any switch might cause a trip. Thus I suspected there may have been some other reason.

Thought I'd swap back to the old switch, as was suggested, while in the process I re-checked (again) all connections in both the switch and the cooker connection unit and found the neutral on the latter very marginally loose - a quarter turn at most on one of the two securing screws. I therefore undid and re-made all connections on both sides nice and tight and refitted the new (not old) switch, just to see if that was it...So far it hasn't tripped since doing so (on Friday) so I'll see if that has cured it, but if it trips again I'll fit the old one and take it from there...Trial and error..eliminate one thing at a time.