We have lived in our flat for 10 years which has economy 7 storage heaters and a hot water heater which all charge overnight. At the moment the off peak times are midnight to 7am. In November, we had the elements of the main heater changed, and everything was fine. Over Christmas, we awoke to find that the RCD switch had tripped out. After testing different appliances, we have narrowed it down to the newly repaired heater. It trips out at around 4am, each morning, and will continue to do so once reset unless we turn it off. Is the problem with the heater, or is it something to do with the energy supply? Why 4am? Any ideas greatly appreciated, a local electrician could not help, and we can't have someone here at 4 in the morning.