Can I add PIV to lighting circuit with no RCD protection?

[Phil C]

As I've mainly done site work and moved into domestic recently, I'm a bit rusty on stuff like this, but if I'm adding a loft PIV unit to an existing lighting circuit via an unswitched fused spur, if the lighting circuit has no RCD protection am I allowed to install it?

Same question for if installing a new socket to a ring, or an extractor fan etc.

 

[nicebutdim]

No to all. Also would require a means of isolation for PIV - pulling a fuse wouldn't be acceptable.

I don't mean to seem disrespectful, but this isn't the sort of issue to be rusty on.