Most extension leads have multiple sockets that allow you to plug in multiple appliances. However, the number of appliances you can run off an extension lead will depend on the wattage of the appliances and the amperage rating of the extension lead. For example, if you have a string of lights that use 50 watts and an extension lead rated for 10 amps, you would be able to run five sets of lights off the lead.nnHowever, if you had a hair dryer that uses 1800 watts, you would only be able to run one hair dryer off the lead, even if it was rated for 15 amps. As a general rule, it's best not to exceed 80% of the amperage rating of the extension lead. So, if you have a lead rated for 10 amps, it's best not to plug in more than eight 100-watt appliances.