RCDs tripped

[Vicario]

I have four plug-in RCDs protecting the washing machine, dishwasher etc. (all on the same ring main). Yesterday they all tripped when nothing was being used. Re-set with no problems, so I was wondering what could have caused this.

 

[bernardgreen]

Some types of RCD will un-set if there is a power failure. They then need to be manually reset when the power is restored.

For all of them to trip that is the most likely reason.

If the four appliances all has their own significant Neutral to Earth fault then it is possible that a very large load ( electric shower, large motor starting ) on the same neutral bar in the CU would cause the RCDs to trip but this is most unlikely to have happened.

What make / type of RCD are those that tripped ( or unset themselves ) ?

 

[ericmark]

Thunder storms can some times send spikes down the line that will trip RCD's the latter designs are less prone to this but with active RCD's even a power failure of a few seconds will trip them.

The electronics in modern RCD's need some voltage to work. If that voltage is not there the active type fail safe. The passive type will continue working so with a passive type one needs the measure the loop impedance to ensure if there is a fault the MCB will fail before the voltage is dragged below the point where the RCD will fail. So most plug in types are active and most built into consumer unit types are passive.