Families putting up the fairy lights this weekend have been urged to take precautions against faulty electricals.
As most of the UK puts up their decorations with only two weeks to go before Christmas, the Electrical Safety Council warned that 13 million homes do not have crucial RCD protection, which cuts electrical currents and can prevent electric shocks.
The charity said the festive period is a dangerous time for electrical accidents, which injure 1.2 million and cause 70 deaths every year.
Phil Buckle, director of the Electrical Safety Council, said: "Think of your family's safety this Christmas by checking you have RCD protection, and if not buy a plug-in RCD which costs less than £10.
"An RCD is a life-saving device that quickly turns the electricity off when danger arises to reduce the risk of death or serious injury.
"Check that your Christmas lights are not damaged or broken before use and look out for loose wires. And unplug them before you go to bed or go out - even Christmas lights need a break.
"Be careful not to overload your plug sockets with new electrical Christmas presents," he added.
Help with checking whether you have RCD protection is available on the Electrical Safety Council's website, www.esc.org.uk.