Originally Posted by Caddyshack

I did, I checked with the manufacturer, these ones are made for rally cars to be always on, they run 20 amps and not 60 amps.

The difference is that the main stream ones are designed for a quick defrost on a driveway so they cannot be left on and therefore timed. The one I am using is to stop the screen misting up so runs as a constant. It uses two elements, one per side so you run two individual looms, this allows less current.