Hello datcope, This jumper cable is included complimentary with our transformers in the event that a photocell or extension cable which does correspond with the photocell plug in the transformer is used (i.e. male plug to male plug, or prong-to-prong). The part is not always required for operation but, it is certainly handy to keep around for possible future purposes!
Evan, That is one more reason I am excited that I found you guys! Thanks for the answer to my question.
Without actually seeing a diagram of that unit, I would suggest that the secondary is the two red wires. You would see about 15 volts ( open circuit). That is about normal to give you 12 volts under load. The white wire is the center tap, hence 1/2 the voltage from each red to the white. percentage calculator
