Electric Wiring behind plasterboard / other wall types

[spiidey]

How would we find out whether there was electric wiring behind a bit of plasterboard or other wall type, without actually taking the part of the wall completely away?

The reason I ask is, if we're drilling a hole in the wall, or putting screws in / raw plugs in, how do we know which parts of the wall are safe to drill / screw, or what should we do prior to drilling / screwing?

 

[Dave2010]

get something like this

http://uk.rs-online.com/web/p/cable-metal-stud-detectors/0418369/

you can get cheaper ones but i found them to be ineffective. The one above i believe to be very good

 

[1john]

Presume cables to be running with in the horizontal and vertical plains of all accessories and withing 150mm / 6" of internal corners as well as above.

 

[Taylortwocities]

Cables SHOULD be in these zones
//www.diynot.com/wiki/electrics:installation_techniques:walls
but this will be according to the diligence of the installer.