Hello, I'm using the arduino to control a relay (crydom EZ240D18) that turns a water pump on and off at a given time each day. To save water, I've been testing the setup with a box fan instead of the water pump. Everything was working fine.
After testing was successful with the stand-in fan, I plugged in the water pump and the relay turns it on, but not off!
I think it may have something to do with the fact that the box fan did not have a ground pin on it's electrical cord. The water pump does have the third, ground pin.
And here's a description of my project with pictures: http://cameronzotter.com/watering-system/
Here's a picture of the relay: http://www.flickr.com/photos/command_z/6965106501/
Any ideas? Thanks!!!