Paul, so you are saying that it would be fine to just cut the plug off of my American lamps and install a Uk one?
As far as the cord itself is concerned, yes. There are two considerations for the cord: One is the maximum voltage it can handle, which is determined by the type and thickness of insulation. Even though it's most commonly used on 120V, American SPT1 lamp cord is actually rated for 300V maximum, so that's not a problem.
The second consideration is the maximum current the cord can carry safely without overheating, and that's determined largely by the actual size of the wires inside. When it comes to a simple light bulb, power is the product of voltage and current, i.e. Watts = Volts x Amps.
That means that for any given wattage of bulb, the current at 240V will be half that at 120V. For example, a 60W 120V bulb in the U.S. will draw 0.5 amp of current. A 60W 240V British bulb will take only 0.25A. Thus there is absolutely no danger of overheating the cord, because for the same amount of power you will be drawing only half as much current -- It's the
current which causes heating, not the voltage.
The one thing which does need more care is the actual bulb holder (and integral switch, if present). Some of the types fitted on American lamps are not intended for operation on the higher voltage. Although you might often "get away" with it, obviously it's not something I would recommend as you don't want to take chances with 240 volts.
If you have a look in the
Technical Issues thread, I mentioned this briefly in my first post, then there are some more related comments in replies #15 & 16.
