How to repair faulty Christmas lights

'Tis the season to be jolly – but it's hard to stay jolly when those fancy lights you invested in last Christmas are already flickering out after a year in storage…

While dodgy lights can cast a shadow on your decorating, fixing the problem isn't always difficult. Here's our list of common problems and solutions to get your home merry and bright again soon.


Please remember to unplug all strings of lights when fixing them in order to avoid accidents.

A blown fuse renders the whole set unusable

A full string of faulty bulbs is an indication that the fuse has blown. Annoying, yes, but also relatively easy to test and fix yourself.

  1. Unplug the string of lights.
  2. Take the plug. Using a small screwdriver, unscrew the plug's lid.
  3. The easiest way to check if the fuse is broken is to use a multimeter. If you are multimeter-less, pop the fuse into the plug of another appliance that you know to be working. This will show you quickly if the fuse is to blame or not.
  4. If it does turn out to be the fuse, simply pop in a new one – a spare usually comes with the lights, or is otherwise easy to find in any hardware store – and screw the plug lid back on.

One defective bulb affects the entire set

Christmas lights are wired in a series whereby electricity has to flow through every individual bulb to reach the next. This means that often if one bulb blows, the rest of the bulbs on the circuit have no access to electricity and won't light up. Investing in a specific light-maintenance device from any hardware store will save you time tediously trying to find the rogue bulb, but if you'd like to solve the matter yourself, it's not too hard a job.

  1. Unplug the set of lights.
  2. Ensure there are no bulbs missing.
  3. Gently tug on each bulb to ensure they're all correctly attached to their socket. If one is loose and can be re-attached firmly then this may fix the problem.
  4. Check that the copper wire within each bulb is sturdy-looking and not frazzled. If too much voltage is fed through this wire, it overheats and snaps. This causes the bulb to break.
  5. If you find a frazzled bulb that may be the culprit, gently twist the bulb out of its socket and replace it with a new one. A couple of spares usually come with the set, and otherwise can be picked up at most hardware stores. Just remember to buy the correct model.

Untwist your light tangle with care and avoid breaking bulbs

If there's one thing Christmas lights are good at, it's mysteriously getting themselves into an entangled ball that would intimidate even the most skilled and nimble hands. But with a little patience and a sprinkling of Christmas cheer, you'll get them untangled in no time. Try these tips:

  1. Unplug the lights, pop on some Christmas music and make yourself a cup of tea. It's important to feel relaxed before getting into untangling lights, as it can be a frustrating task.
  2. Lay the lights out on a flat, clear surface so you can see them clearly.
  3. Try and find a loose end to begin with and try not to lose this throughout the process.
  4. Have a pencil on hand to help gently prise the strands apart from each other.
  5. Lay out the strand as you untangle it and keep it apart from the rest of the bundle.
  6. Be patient! This is key in untangling lights, as it is with anything finicky. Try and keep in mind how fabulous your tree is going to look at the end of your hard work. It'll be worth it.

Remember: Keep your exterior lights protected

If you have installed outdoor Christmas lighting, ensure the circuit or equipment has RCD protection. If your power supply doesn't have a built in RCD unit you can purchase a plug in device which will provide you with RCD protection and provide you with extra protection.

Remember: Always water real Christmas trees

Christmas trees are prone to dry out very quickly, resulting in them becoming flammable, keeping your tree watered ensures your tree remains as safe as can be! 

As the jolliest season of all is upon us, let's not get bogged down by faulty lights. Remember that if you have any hesitations about fixing your lights yourself, give our engineers at HomeServe a call, and see how we can help.