Please read my page: Isolating Power Points and Light Switches. It is also advisable to protect all light switches and power points from the risk of water infiltration from either excessive steam or water running down the wall whilst steam stripping. For information on Shielding Electric Power Points and Light Switches follow this link.
Great care should always be taken whenever you are using a steam stripper to remove wallpaper from around electrical power points and light switches, even if the sockets have been isolated (Turned Off).
Never place the steam plate over a power point or light switch, It is also advisable to never hold the steam pan stationary above a socket, by constantly moving the steam pan around on the socket the paper and gently steaming the surface the wallpaper will soften and the wallpaper can be removed with your wallpaper scrapper. Avoid water beads running down the walls and onto the electrical sockets and switches.
You can position the steam pan right up against the edge of the socket as long as you do not allow an excess of water to build-
If moisture enters the switch or socket you might hear a hissing noise when live (Not Isolated), do not touch the socket and isolate the power source immediately at the consumer unit. It may be necessary to loosen the socket from the wall surface for it to fully dry out, gentle warming of the socket with a medium heated hair dryer should help evaporate the moisture from within it. Do not reconnect the power source unless you are fully confident all the moisture has evaporated and the socket is completely dry.
Remember ELECTRICITY CAN KILL so do not take any unnecessary risks, if you are uncertain about what you are doing, then do not proceed and seek help from an electrically competent and knowledgeable person.