I used the grill for the first time in my six year old cooker (Electrolux EOB3400AOX). After a few minutes, the RCD tripped and now whenever I turn the heat on the RCD trips (although the clock and oven light work without tripping the RCD).
If i turn the temperature dial past 0, even when the cooker is off , the RCD trips.
it more then likely a damp element.
if elements are not used they soak up moisture out of the air. When you turn them on they try to let out the moisture and this can blow the trip
if you take the element out and put it in an oven for 2 hours or so it may dry it out enough if not you will need to replace it