OP
WDMDL
My opinion, without seeing anything, is that the high supply voltage is the problem.
It's not likely to be outside of the limit (253V) - but it is feasible and if verified as outside the limit, the DNO should investigate and take remedial action.
The reason lamps blow at switch-on is that (particularly with halogens) the filament has a much lower resistance when cold.
So, at the instant of switch-on, a large current flows which results in a large magnetic field around the delicate filament. It twangs violently, snapping at the weakest point.
Obviously, with a higher than normal supply voltage, the current will be higher.
Then, the resulting arc ionises the gas in the lamp - so the lamp then appears as a short circuit, the fault current causing the MCB to trip (and destroy your dimmer).
I'm generally up in Cleethorpes a lot, but don't think I'll be there in the next week or so... though I have a heating install to do on a holiday home up there in the near future.
Simon.
It's not likely to be outside of the limit (253V) - but it is feasible and if verified as outside the limit, the DNO should investigate and take remedial action.
The reason lamps blow at switch-on is that (particularly with halogens) the filament has a much lower resistance when cold.
So, at the instant of switch-on, a large current flows which results in a large magnetic field around the delicate filament. It twangs violently, snapping at the weakest point.
Obviously, with a higher than normal supply voltage, the current will be higher.
Then, the resulting arc ionises the gas in the lamp - so the lamp then appears as a short circuit, the fault current causing the MCB to trip (and destroy your dimmer).
I'm generally up in Cleethorpes a lot, but don't think I'll be there in the next week or so... though I have a heating install to do on a holiday home up there in the near future.
Simon.
