Vikki
!/ I assume that this doesen't happen in manual, if it does then there may be a fault further down the line if it doesen't the fault probably lies with the timer.
2/ I am also assuming the trip switch in question is the RCD or Earth leakage circuit breaker i.e. all your sockets go off as well. in this case I think there is a small earth fault developing or a small current imbalance that is causing the switch to trip the RCD and you may need to replace the switch.
3/ assuming that the circuit breaker / trip switch to the boiler is tripping, the timer is creating some form of short circuit and will still need to be replaced
Kenny F, December 2008
