Top tips from electricalsafetyfirst.org.uk on avoiding overloading sockets.
You can avoid overloading sockets and risk of fire by following this simple advice:
Check the current rating of the extension lead before plugging appliances into it. Most are rated at 13 A, but some are rated at only 10 A or less - the rating should be clearly marked on the back or underside of the extension lead. If not, refer to the manufacturer’s instructions
Never overload an extension lead by plugging in appliances that together will exceed the maximum current rating stated for the extension lead. This could cause the plug in the wall socket to overheat and possibly cause a fire.
Use the overload calculator (below) to check if you’re exceeding the maximum load
For a brilliant socket overload calculator visit here