The particular unit you have is rated 800 Watts @ 120 Volts incandescent.
This, and other control products with similar ratings would lose their smoke in short order if someone was to plug in ie: an 1800W blow dryer to a receptacle it controls.
I believe the electronics are operated between the hot and the equipment ground, rather than through the load. Here's a pic of one without an equipment grounding connection. (277V system)