HID Ballast Wire Colors

[dduffee260]

I have an older 1500 watt HID ballast that does not have a wiring diagram, or the wires are not labeled for the voltage. They are 480 volt now and are wired yellow and blue. The other wires are red, black, orange and brown. Ususally the wire are labeled with the voltage on them but this one is not. Can anyone tell me which wire is the 240 volt wire? I want to say blue is the common by the looks. There is a quad tap voltage sticker on the side of one fixture but there is nothing about 480 volts there. Could this be a 5 tap ballast? The lights are about 12 years old. Thanks for any help.

 

[LarryFine]

While energized, (carefully) measure the voltage between each tap and either the blue or yellow wire, whichever gives you approximately the expected voltages between them.

When energized at any voltage using the correct two wires, all of the others will have their corresponding voltages on them, due to the auto-transformer behavior of the primary.

 

[fishin' electrician]

You might even be able to tell visually by where the taps come off the windings.