It's OK, I know now. 110 volts at 3.7 amps, roughly 400 watts. 750VA transformer required is part number 73851 (or you can future-proof yourself by buying the 3kVA unit 16158), plug is 19947, optional 14m extension cable is 16691.
NOTE: when fitting plugs to USA mains cables, the colour coding is not what you'd expect - WHITE=Neutral, BLACK=Live.