by ericmark »
Tue Jul 30, 2024 5:27 am
An RCD monitors the in and out current and assumes if they don't match, the current is going to earth, There is always some loss, as we use AC, so there is some inductive and capacitive linking so typically we use a 30 mA RCD.
We should when installing monitor the background leakage which should not exceed 30%, but in the early days we had little option, the early consumer units were not designed to use a RCBO (MCB and RCD combined) so we had all on one or two RCDs.
The result is it can be hard to be sure what is causing an RCD to trip, with neutral to earth faults the load has a big effect, so a fault with a bit of damp toast in a toaster, can trip the RCD when the kettle is used, so since the washing machine is a high load, it could cause a trip when the real fault is something else plugged in.
So step one, ensure nothing else plugged in.
Any mineral insulated heating element will draw in moisture if the seal is damaged, So ovens, washing machines, resistive tumble driers, frost free freezers, all have these elements, the test is to use 500 volts DC to measure the resistance, this uses a special tester, the other method is to measure the AC leakage with a clamp on ammeter, the problem for the DIY man, is likely they have neither, and it is a lot of work and expense to swap a heating element to see if that cures the problem.
Since I have both, for me, it is easy, they are not super expensive, around £35 but still a lot of money for a one-off use, so do you know anyone with one you can borrow?