The upper limit allowed for portable electric household space heaters is 1500 Watts. Most have this as their high setting and then one or two lower wattage settings as well as thermostatic control. I believe they all are now required to have a safety switch that turns them off if they are knocked over.
Agreed... and 1500 watts is 1500 watts no matter what unit you buy... efficiency is what you want to go with... I have this heater
... and it works extra efficient! I have these in the home in each room and is more efficient than the central heating in the house! Trust me when I say this heater is the best I've bought... it's ceramic and retains the heat for a long time... oscillates and has many features... and most of all it's 1500 watts!