[Concealed fire door closer]

Why are you fitting a closer to a cupboard? 
Doors need specific test evidence to permit the use of concealed closers, and hinge side mounted closer bring their own set of unique obstacles. 

[Does a screwed-on fire door sign make a fire door invalid?]

On 23/02/2021 at 10:03, Guest Jo Scott said:

Whilst on the subject of screwing things to fire doors, would fitting access control magnetic locks (linked to the fire alarm system) to a fire door invalidate its certification?

It depends on the door and the certification it has.if I had to say ‘generally’ it would be that maglocks using through-door fixings should not be fitted where avoidable and definitely not above a glazed aperture.