[QUESTION HAS BEEN ANSWERED. THANKS TO EVERYONE WHO CONTRIBUTED TO THE DISCUSSION.] So, let’s start off with this: Volts * Amperes = Watts. The standard North American AC voltage is 120V and the standard amperage is 15A. That gives us 1800W to work with.
Let’s take a look at the British standard. BS 1363 is (most commonly) 230V and 13A which gives us 2990W. German standards also allow up to 4000W if I’m not mistaken. What caused these differences?