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[sparky kilowatt]

If you can trace the wires out to a lamp socket, the outer ring with the threads is the grounded leg, the tip or center of the socket is the power. For a low voltage incandescent bulb, it really won't matter if you reverse the polarity, but if you're going to convert it to LED the polarity matters. My suggestion would be to try it with a 9v battery and see what you get.