benpost wrote:
thought it would be easy to replace a faceplace for a plug
socket....but when taking the old one off, most of the surrounding
paint/plaster has come away. now im left with a sandy/crumbly area
around the back box.

how can i repair this?? the hole now is a lot bigger than the
faceplace. should i get plasterer to do it or can i use filler? will i
need to put pva on the sandy area to seal it ?

How big is 'a lot bigger'? Inches, feet? How deep?

I'd start by using a slightly dilute PVA mix (2 water, 1 pva) to
seal and glue up the sandy crumbly area. Then build up with filler
in several layers if necessary followed by decoration.

Guy