The likelihood is that there will be even more digital/electrical goods being given as Xmas presents this year - and everyone wanting to try them out immediately! This could put a temporary strain on domestic circuits, especially if there are hidden faults waiting to be exposed!The first sign of any trouble is likely to be an electrical appliance that appears to be dead! Incorrect 3-pin power plug wiring must always be suspected and checked - bare wires touching cause shorts, or worse! If a plug fuse has blown, it's not always obvious, so replace with identical rated and known working fuse( pre checked in another appliance or with a circuit tester).Always check the fuse box /electrical panel to see if any circuit breakers are tripped or fuses blown.When lights go out in domestic household, it is invariably a problem of 'loose' or lack of connection or a temporary circuit overload due to plugging in a device that draws more supply than the ring circuit is rated to supply.Use a circuit tester to see if the outlet that the lights are plugged into is hot. If not and the circuit is on, turn the circuit off, remove the outlet, and check the connections to the outlet.Of more concern is if the lights suddenly go out! The first weakness will show up with the Christmas Tree lights and you will need to check individual light bulbs. Often the cause of the problem may simply be that one or more bulbs are loose in their sockets, a bulb could have fallen out completely or a bulb wire bent to the side so it isn't making contact.It may be as simple as a fuse blowing within the light set itself. Located within the plug should be a couple of fuses. They are hidden behind a sliding door that is clearly marked. Simply unplug the lights and slide the cover to expose the fuses. Remove the fuses and check them with an ohm meter. If there is no resistance, they are good, but if there is infinite resistance, they are faulty and should be replaced.IMPORTANT : Regulations are very strictly defined as to what you can and cannot do with electrics around the home, especially when it comes to house rewiring and installation. Short weekend courses are always available for all those who would like to find out more and for those who wish take their knowledge further, perhaps with an eye on their future, more fulltime NVQ electrical courses which can include the all-important Part P, can be undertaken to obtain City & Guilds qualifications.