Every year the same problem! Tis the season to promise that the lights are put away neatly!

There are two types of lights normally available, incandescent or LED.

Incandescent lights are the 'normal', or 'old fashioned' sort and normally come with 20, 40, 60 or 100 bulbs on a green wire and plug into the mains electricity. Coloured lacquer on the clear glass bulbs give them colour.

LED bulbs are very small, give an extremely bright light and are manufactured in many colours, including vivid blue which is curently very fashionable. Rope lights are also popular, these are LEDs too. LEDs work on a very low voltage, under 1.5 volts, and and in some cases are run from batteries, they also use very little power but despite this a set of LED lights will use up a set of batteries within a day. The 'portable' battery powered LED light set is most useful for seasonal fancy dress and very small Christmas trees.

LED light repair

LED lights are the most difficult to repair as they work on a very small scale, use electronics and are not typically equipped with user replaceable bulbs. On the plus side the bulbs almost never fail.

What may fail is the battery (if they are powered in this way) which is easily replaced, the fuse in a mains powered set (replace but make sure you use the correctly rated fuse - typically 3 Amp), or a connection may be lost within the set - a common problem in rope lights. If some of the lights in your rope are not working try bending it at the point they appear to stop, this may remake the connection - there is little more that you can do without specialist knowledge and tools.

Incandescent light repair

This is the old chestnut, the lights are not working and it seems a neverending task to find the one bulb that is the problem.

Don't be blue! Follow these guidelines and you'll soon have a glowing set of lights and be the pride of the family!

A little understanding is needed first.

Lighting sets are sequentially wired, the electricity passes through each one in turn, if a connection is lost in just one bulb the whole set will go off. To avoid this bulbs short out when they blow which allows the current to continue to pass through and all of other bulbs will stay on.

However, since the voltage is shared between all of the bulbs, as bulbs blow a higher voltage flows through the remaing bulbs increasing the chance of them blowing.

To avoid a domino effect occuring all lighting sets should have a fuse light in them, this is identified by having a white tip. When this fuse light blows it doesn't short out and all the lights go out.

How to fix a set of lights

Note: Unplug the set when working on lights! Plug in between each step to see if they are fixed.

1) Replace any missing bulbs. If any are missing none will work. Spare bulbs will have been supplied with the set, either in the original packaging or sellotaped to the wire near the plug.

No spares? To buy spares you will need to know how many bulbs in your set, there are also miriad fittings but many are 'sort of' compatible - all modern sets are push-in rather than screw-in. If you have another set with the same number of bulbs you can use spares from that set. Using bulbs with a different rating will cause the bulbs to glow with different brightnesses in your string and shorten the life of the brighter ones - often dramatically.

2) Grasp each bulb and give it a wiggle in its holder if you can, remember the bulbs are glass so take care not to break them they are tough but will eventually shatter! This will help to clean the contacts on the bulb and the bulb holder.

3) Replace the fuse bulb. If no fuse bulb is available you can use an ordinary bulb but you run the risk of blowing all bulbs if there is a problem. The fuse bulb is to save the bulbs, the fuse in the plug is for your safety.

Still not working? You are will now have to start getting serious with your lights!

One of two things is likely to have happened, one of the bulbs has blown and not shorted or all of the bulbs have blown. If you have another set of lights with the same number of lights that is working you are very lucky as this will help enormously.

4) If you don't have another set of lights or any spares there is very little you can do, perhaps try step 2 again. Go out and buy another set of lights, if you can get the same type you will then have a lot of spares (from your old set) when the new one goes wrong!

5) If you don't have another set of lights but do have spares exchange each bulb in turn if only one bulb is at fault your lights will at some point spring to life. Two tips here i) don't put the original bulb back, use it to replace the next bulb - this will save half the fiddling. Ii) work to a system - start one end and work through, randomly guessing may take ages - unless you can treat it as a Christmas game.

Remember if all the bulbs are blown (or indeed more than one), this will not fix your lights - sorry :-(

6) If you have another set matching yours then take a bulb from your set and put it in the other set, if it works it shows that all of your bulbs are not blown and the fault is down to a single bulb. Set up a system to swap several bulbs at a time, this should quickly identify the faulty one - or two.