I want to take a spur off a downstairs ring main. By far the easiest way to
do this will be to T-off the ring under the flooring, rather than from a
socket. (I'm currently redecorating. so I can get to under the floor.)

I understand that I can't use a standard juntion box, as regs requires that
screwed fittings need to be accessable. My question is - what sort of
fitting should I use?

Thanks

Steve