This is more to do with labelling than wattage. The old phone number gives this cleaner away as being about 16 years old or thereabouts if nothing else and the labbeling is rather odd. The variation in the wattage stated is set against the voltage peak & troughs. The "maximum" wattage here could possibly be set against the cleaner being run at more than 240 volts as our power supply can be very up & down, even though it's more likely to be around 230 for most of the time.