best way to patch hole in plasterboard ?

?source=W2000.....(snip)

Standard technique, I think. Temporarily tack a bit wood through the hole to the back, secure and infill.

Same here.

CJR ELECTRICAL 95% don?t know how to fix this!!

I'd be more inclined to use PVA than screws to hold the backing: put a bit of string through the middle, then loop that around a baton on the front to hold it until the PVA has set. Or you can just add flanges on two or more sides rather than filling the whole hole with backing - those can be held in place with spring clamps until the PVA has set.

You are going to need filler somewhere along the line, so having screw holes to fill does not seem to be much of an issue (so long as you have some proper drywall screws). Saves waiting about for glue to dry.

PVA can be a problem particularly if dust has accumulated on the backside of a ceiling, the screw method is guaranteed success and you don't have to wait for it to set.

Richard

whatever this huge link is about I think at least some text in the message body would be nice since otherwise many would think its spam Brian

I just stuff the hole with newspapper and skim with bonding plaster sometimes