Originally Posted by iadom

The modern RCD's are very sensitive and I have seen machines trip one time then run perfectly for many months before doing it again. I have checked these appliances and can find no trace of current leakage.
In this case I suspect a fault is developing in the motor, possibly the armature, ( may be worn brushes but it would not revolve at all with completely worn brushes) this would cause the RCD to trip when gonig into spin, the arcing that happens at this time can trip the RCD. It is an out side possibility that a wire is loose or chafed, this may only be touching internal metal parts when the machine goes into spin due to the extra sideways movement that sometimes occurs during spin. Also if there is a slight leak the water could splashed around during spin but fall harmlessly on the floor during wash.