Electric shower cutting out

[96terrano]

thought id ask as ive been very pleased with the other non vehicle related questions & answers here

basically, this problem has gone on over a year now, when the counsel fitted new bathrooms back in early 2011 we got new showers too, but in late 2011, it started randomly cutting out, tripping the breaker on the fuse board randomly

some times when you flick the trip switch it would come back on but other times the trip switch just fires off again, we spoke to the counsel and they actually hot glued the switch in the on position anyways that sorted it, then about 2 months later the counsel came back and replaced the shower and trip switch, but the new shower still trips the switch if you have the temp over a certain setting, it seems to be ok now but will still trip say once every 2 months

any ideas?