Originally Posted by lksdrinker
The third "prong" is what grounds the device and is not really "needed" so you can always use one of those adapters. Often referred to as a "cheater plug" or a grounded outlet adapter. Should be less than $1.
If it has a ground plug, you should use it. Just because the device "works" doesn't mean it should be used like that. Safety first and all.
You can pick up a "heavy duty" mechanical timer for less than $10. It has the three pronged outlet. I bought one when I got my setup, and haven't had any issues with it (other than fat fingers messing up the time!).