According to the Advance Ballast Pocket Guide:
The Rapid Start lamp operates on the principle of utilizing a starting voltage which is insufficient to start the lamps while the cathodes are cold but is sufficient to start the lamps when the cathodes are properly heated. This voltage range between starting cold and starting hot is a very narrow band of voltage which must be closely controlled by the ballast in order to prevent either failure of the lamps to start or instant starting of the lamps with cold cathodes which is detrimental to the lamps. In order to stay within this range of voltage, it is necessary to excite the gas within the lamps by means of an external voltage applied between the lamp and the reflector or channel (the starting aid).
In order to act effectively, the fixture must be connected to ground and the white lead of ballast connected to ground lead (neutral) of the power line.
Well, apparently they are relying on the neutral to ground bond at the service for this to happen because what they are saying is they need to have the white wire from the ballast to be connected to the the fixture sheet metal. Grounding the fixture would be the only legal way to accomplish this.
What would happen if the hot and neutral were reversed somewhere in the circuit? Another reason for the fixture not starting?
Going to be bull headed here and still stand on my old argument that a ground is not necessary- there are plenty of 2 lamp 48" rapid start fixtures available as "shop lights" and "grow lights" with 2 wire cords on them. Same ballasts, same lamps and they all start.
I know what you all are saying but I have never had a fixture fail to light because of a missing ground. It's always been because of other things even as weird as incompatible lamps from one manufacturer.
Ever wonder how lamps stay "warmed up" for instant-on when the circuit is "off?"
John, they don't. How could they? What they are talking about is when the fixture is turned off then turned back on while the lamps are still warm.
-Hal
[This message has been edited by hbiss (edited 12-31-2004).]
