Your problem is then having two different circuits in one box. I can't remember if this is allowed. However, if it is allowed, a warning sticker inside saying that several different circuits use the same accessory may be a good idea. This might prevent someone turning off the lighting circuit and getting fried from the ring main based lighting.
Christian.
I'm not quite clear what you mean. If you mean having one switch in the two gang from the lighting circuit and one from the 'ring' (after the FCU), then this is ok - it's common to have two or more different circuits in one switch enclosure in hallways.
I'd stick a note inside the box, though. ;-)
Never assume a circuit is dead because you *think* you've isolated it. Even in your own house where you *think* you can remember how everything is done.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.