Thank you for your question on the model MD6T automatic make-up air damper. The only wiring instructions we would have are the installation instructions that come with the MD6T. If you look at the face of the C909 transformer, you will notice printing that says “24V” and has arrows to two of the terminals. Use those two terminals to wire to the MD6T, there is no polarity. Please contact the Technical Service Department at 800-637-1453 if you further assistance.