Wiring issue Hayward Astrolite

[Randy Anderson]

Hello. I appreciate any input. I bought and installed a pool kit from royal pools and am in the process of wiring the light. Per my paperwork, it's a 300W 12V Astrolite in a dura niche along with a 300W transformer. Electrician became concerned because the cable has 3 conductors at 12AWG (black, white, green). He said that he is used to seeing a cable with 2 wires for the 12V lights and that typically when he sees a 3 wire cable, it's for a 120V light. We tried looking for a wiring diagram for the light but none was provided in the paperwork nor on Hayward's website. Thanks in advance.