Ta, it was the "in case the OP has any lights above a bath or shower, it's worth pointing out that exactly the same requirements relate to luminaires in Zone 1." bit that confused me :oops:
Cheers.
Can you clarify that for me please? Are you saying that if the OP's ceiling is 3m high then a light on the ceiling directly above the bath needs to be rated IPX4?
That's a series 6 house service cut out. That would usually indicate a TN-S supply. The series 7 (ie no earth block at the top right) would normally be used for TNC-S. Of course the series 6 can be reconfigured internally for both TN-S and TNC-S but the lack of the PME sticker does suggest TN-S.
Any idea what is inside the FLA01? Surely it cannot be much different to the snubber the OP is already using - although he needs a X2 275V cap to cope with peak voltages. I am tempted to buy a FLA01 to see what is inside it. I would have thought a 0.47 cap in series with a 100 ohm resistor would...
If there is no neutral at the OP's switch then there would be no use for the DP switch. But you already knew that.
If there is a neutral at the switch then your suggestion is the way forward.
That is true if you are treating the old element as a fixed 24ohm resistive load (dunno what the resistance alters by when heated).
But as you noticed the point I was making is that the change from 2400W to 2300W is not important and the OP need not worry about it.
I would not worry about the 2400/2300W ratings. The 2400W rating is from the days when we used 240V and the 2300W one is for the new fangled 230V that we now use.
I am not sure about that looking at the age of the UKs housing stock.
However your suggestion to try a different RCD is a good one. Maybe a plug in RCD?plugged into a non rcd supply of course :roll: