Patent ID: 7391168

Claim:
A method of enabling communications between a controller and at least one electronic ballast on an AC power line supplying power to said at least one electronic ballast, said method comprising: rectifying an AC power signal on the AC power line thereby creating a rectified power line signal; sending the rectified power line signal to the controller which can activate a switch which shorts the AC power line; using said controller to activate the switch whenever the rectified power line signal approaches a zero crossing for the rectified power line signal thereby extending a zero crossing that occurs when the AC power signal on said AC power line either transitions from a positive to a negative polarity or from a negative to a positive polarity; and detecting a presence or absence of a zero crossing extension when said AC power line signal changes polarity with said at least one electronic ballast and interpreting said presence or absence of said zero crossing extensions in accordance with a predetermined code to thereby enable communications between said controller and said at least one electronic ballast.