In the last two weeks we've had maybe seven or eight powercuts at pretty much the same time - between 9.05 and 9.20pm - its only us, not the street. A couple of these have happened as we've turned the oven off, but most have occurred when nothing has been turned off or on, tonight's was pretty typical, just watching telly and boof, shutdown. Anyone have any ideas?

Electric heating/immersion heater coming on with timer?

Security light being triggered?

Neighbour tapping in?

Boiler's a combi and the tap's are not running, at the time, no security lights. The tapping in had crossed my mind (is that bad of me?) but doesn't seem feasible, and even if it was why would happen within that 20 minute window.

How do you get the power back on? Reset a fuse or is it just coming and going of its own accord?

Flick the fuse back on. Now you say that, I guess if I had a torch handy I could see what part of the circuit was tripping. Trouble is, torches are like pairs of scissors in our house - them darn kids are always taking them and hiding them away.

Ah...not really a power cut is it? Obviously it's a surge of electricity at that time of day that trips the system. Stating the obvious, you need to have a sparky to look/check over your electrics....

I see, thanks.
Still a bit weird that happens at the same time.

Do you have anything set to come on/go off like the boiler?

Also, if you can remember which fuse trips, then you can form a list of items that might be causing the problem.

You may have a sensitive system, there may be a change over of power from your power supplier at that time of night. Worth having a professional checking over everything, if not just to make sure everything is in order.

Well the first step is to find out which circuit is tripping and then start looking at items on that circuit.

It could even be just a 'weak' trip, but find the circuit first.

Ok, so powercut again last night and none of the individual cicuits had tripped - only the big one. Hmm. Time for a spark.

In the meantime, you could isolate specific circuits to see if that prevents the main trip. That will help narrow it down when a sparky comes

Electric cooker being used at the time?

Electric shower?

Kettle?

What fuse or breaker is tripping? Size fuse?

Has the Earth Leakage breaker tripped? Some sensitive systems even trip when a bulb (sorry lamp) blows too.

Highly unlikely, although not impossible that you have a incomer fault but more likely something daft like even plugging in a faulty phone charger or an overloaded circuit.

You recently bought any new electrical items?....

Ps if your heating comes on even with a combi boiler, it requires an electric spark to ignite the burner. What time is your heating or hot water set for or are you manually adjusting the temp at those times......

Only the big one indicates that the main switch is an rcd and that is tripping so could be a earth leakage fault on any of the circuits, as the individual breakers wouldn't trip under that situation, there is mysterious thing called nuisance tripping that even Sparkeys can't explain.

That's why I'm suggesting isolating individual circuits (where possible) to see if you can narrow it down. It's not perfect but I can't think of a better way. And even that isn't fool-proof

Solved!
For anyone out there still scratching their head and filling their spare room with clippings from wiring diagrams and string, its solved. It was ...

...The oven. When the oven was reaching a certain temperature - hence the evening outages - the element was expanding to a point where the wiring was touching and, et voila, kaput.

Thanks to everyone for their input.