Adding a Ring Main

[bongos]

mm, Not sure how they could sell it as 17th edition maintainance free if it isn't?

That's how the argument started on the other post I linked.

526.3 Every connection shall be accessible for inspection, testing and maintenance except...

It goes on to name exceptions but a maintenance free junction box is not one of them. Although Ashley state their JB is maintenance free, it is not accessible if is hidden away under floorboards/behind wall etc, so in this case it would not comply.

Best get the crimper at the ready...