JimH2 said:
The UK uses 110V (@ 50Hz) on job sites for safety reasons, but I do not know if it is required or just done for safety.
I don't think it's actually required (I may be wrong on that), but I believe it's generally done because they feel exposed cords are more prone to damage on a job site. If you damage and short a cord 55 volts gives less of a jolt than 240 volts. Jobsite voltage is 110 available volts but because of how it's wired each current carrying wire only has 55 volts, same way US 240 volts is actually 120 volts on each current carrying wire.
One other note on UK 240 volt plugs and wiring. They usually (always?) have a 13 amp fuse wired into the plug.
Because of how their 240 volt circuits are wired (it was designed to use thinner wire to save money/materials) the available current is 32 amps I believe, but most of the things plugged into the circuit have wiring that can only handle 13 amps. If the plug didn't have the smaller fuse and the appliance had a short the higher available current would fry the wire and potentially cause a fire. This way if something shorts it will blow the smaller fuse before the current gets too high for the smaller wiring.
That's a lot more info than I originally intended to dump....