My economy7 timed water heater trips the electric when coming on in the early hours.

Dear Customer, There may be more than one cause or multiple faults for your tripping. It could be your eco- 7 switch making both heaters lives at same time, heater coil in water tank may have earth fault or your breaker overloading by timer to switch both heater at same time or you could have fuse spur switch wiring fault!! Log your job in to this site and find expert help with qualified and experienced electrician. All the best! VIN OHMELECT

The most common fault is that the Immersion Element is faulty they corrode then let water in then short out. The answer is to replace the element unfortunately this is not really a DIY job most good Electricians or Plumbers can replace these elements so put the job up on my Builder. Hope this helps if it does hit the Like Button Kelvin

the element has probaly gone but if you have to ask how to test it then dont. Get an electrician to do it, because the safest way to test it is with very expensive meter equipment. kevin.