According to the NEC 680, a pool light MUST be on a dedicated circuit, not on the pump circuit, and not on an auxiliary circuit.

I have an ABG, and I have three GFI breakered circuits for the pool. One for the pump, one for my Aqualuminator (which we love), and one for the auxiliary outlet and area lighting circuit.

Do NOT plug in your Aqualuminator or other pool lighting into your auxiliary circuit.

More info can be found in this thread.