Most people have extension leads in their homes, using 4-way bar adaptors to increase the number of appliances that they can plug into a wall socket.
However, although there is space to plug in four appliances, this does not mean it is always safe to do so. Different electrical appliances use different amounts of power. To avoid the risk of overheating and possibly fire, you should never plug into an extension lead or socket appliances that together use more than 13 amps or 3000 watts of energy.
Use this calculator from the Electrical Safety Council to see the effect of plugging in extra appliances on the load, and to get useful tips on how to avoid overloading your sockets.