Most people use extension leads to get more sockets in their homes or workplaces; but most people are also not aware that even though there are (for example) 4 socket spaces to plug in 4 appliances, it does not mean it is safe to use all 4 sockets.
For example, are you aware that most 4-way leads have a maximum current rating of 13 amps or 10 amps; which means you could be overloading it if you plug in appliances that exceed the maximum current rating stated for the lead.
This could cause the plug in the wall socket to overheat and it may even catch fire.
For example, if you use an extension in the kitchen and plug in a toaster that is around 8amps, drawing around 2000 amps; out of the available 13 amps on the extension, that doesn’t leave room for your kettle – put the kettle on and you have an overload.
Another example, if the extension lead is behind your TV, with the TV, Sky box and DVD plugged in you’re going to be perfectly fine as between them they’re only using around 1.5amps; meaning you still have plenty spare room for using the 4th socket; but just make sure that doesn’t overload things – don’t plug your iron in for example!
What many people don’t realise is when extension leads were mass produced, it was because of the amount of IT equipment we were getting in our houses; they were designed for use with computers, and home entertainment systems – appliances that don’t draw too much power.
Have a go for yourself by using this overload calculator from Electrical Safety First to check if you are exceeding the maximum load
For an indication of the current ratings of commonly used domestic appliances see this list on Electrical Safety First
Top tip – Only use one socket extension lead for each mains socket, and never plug an extension lead into another extension lead
If you use extension leads regularly, consider having more sockets installed
If you must use extension leads; don’t use socket blocks as well, or instead of, as they put more strain on the socket – some don’t even have a fuse, which increases the fire risk from an overload.