Annual ADSL and Christmas lights do not mix warning!
It is that time of year, that you either love or loathe. Yes Christmas is here, and it is time for the annual ADSL health warning message.
If you have ADSL and you have Christmas lights that flash, you may end up with an intermittent ADSL connection. Therefore if you have any ADSL problems, the first thing to try is switching off your Christmas lights. The problems are generally linked to lights that flash, since these are more prone to generating RF interference that can affect ADSL. In theory CE marked light sets should be OK, but there is the chance of grey imports which may not actually meet all the European standards.
To avoid problems, it is generally best if you keep wiring for your Christmas lights away from the telephone wiring, and avoid running the cables parallel to each other.