Tonight I visited my local electronics catalogue store (Kjell & Company in Stockholm) to buy a new charger to replace my spare telephone charger which has been powering my Pi for the past few weeks. I had selected one which was small, cheap and specified at 1000ma, but when I went to order it the assistant said that it (and a number of other similar USB chargers) had been withdrawn from sale and sent back to the suppliers. The reason being that they did not meet the requirements of the CE certification and could be dangerous under certain conditions. The assistant pointed me towards a more expensive, larger but better built charger which suited me fine !
I had never thought about USB chargers before buying the Pi, and have spent far too much time thinking about them since
