Homeowners have been warned about the risk of electrical fires when misusing a heater unit this winter, after a man in London died in a blaze thought to be started by his electric heater.

London Fire Brigade released figures showing the number of fires caused by such heating appliances has climbed to 310 over the last four winters. While they account for just five per cent of all electric fires in the capital, one third of deaths occurring during these fires has involved an electric heater.

Ron Dobson, the London fire commissioner, commented: "I'm concerned that with the cold weather set to hit London this weekend more people will be pushed to use portable heaters to keep warm.

"During winter, we're seeing one fire a day caused by heaters that have fallen over or set fire to clothes or furniture. People need to make sure their portable heaters are standing upright and kept well away from clothes or furniture."

Phil Buckle, director general of the Electrical Safety Council (ESC), also raised concerns about the safety of electric heaters.

"A number of people take electricity for granted and pay a serious price. By following a few very simple safety precautions you could save a life," he said.

It comes after the EST's research in September revealed the number of fires caused by misuse of appliances was on the rise and that many homeowners take risks without realising.

The most common blunder was using microwaves as an extra surface and blocking their air vents, while nine per cent of people regularly left their tumble drier switched on without keeping an eye on it.

Another frequent no-no made by homeowners is overloading adaptor sockets, which can cause an unsafe rise in temperature and lead to the fuse board blowing.

But there are steps you can take to protect yourself against electrical fires starting, including fitting your fuse box with a residual current device, which can reduce the risk of fire by automatically cutting off the power if a fault occurs.