This isn't a poor earth that is causing it to trip. it is an earth leakage fault through one of the components inside the appliance.this will need finding and replacing.normally it is related to a heater fault which is damp.if its a condensor dryer it could be a damp element caused by a faulty drain pump allowing water to get picked up by the blower fan and spraying on to the heating element.
ck, April 2009
