just a couple of comments here on an inexpensive and useful device: in case you wonder, this device plugs into a three-prong outlet, just like the plug it accepts from the controlled device. I wondered if I needed to connect it like a new outlet, or plug it into an outlet - now I know and so do you. Also, the time-adjustment knobs are not too well calibrated perhaps - well the off time seems about right, but the on time is spectacularly off: when I set it for one minute it stayed on for over eight minutes. But when I tweaked it down to thirty seconds, it stayed on for 90 seconds. Not linear, so you may have to fiddle with it to get the desired operation. Mine runs a 1/4 horsepower water pump.
Not precise equipment, but gets the job done.