Sounds like this pool light installation has some very serious problems.
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300.3 (B) Conductors of the Same Circuit. All conductors of the same circuit and, where used, the grounded conductor and all equipment grounding conductors and bonding conductors shall be contained within the same raceway
680.23 (F) (2) Equipment Grounding. Through-wall lighting assemblies, wet-niche, dry-niche, or no-niche luminaires (lighting fixtures) shall be connected to an insulated copper equipment grounding conductor installed with the circuit conductors. The equipment grounding conductor shall be installed without joint or splice except as permitted in (F)(2)(a) and (F)(2)(b). The equipment grounding conductor shall be sized in accordance with Table 250.122 but shall not be smaller than 12 AWG.
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originally posted by aldav53 The pool light switch has a 15a circuit run to it, I could tie it there. There no #12 bond wire at the switch. I believe the bond for the pool light is bonded at a different point. Probably the panel, or somewhere in the pool filter area, to a water pipe maybe?

300.3 states that all the conductors of the same circuit are to stay together.
680.23 (F)(2) states that the equipment grounding conductor must be #12 and be insulated
In your statement the conductors supplying the pool light is #14 which in itself is a violation. Now you say there is no grounding conductor present at all.
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680.42 (C) Interior Wiring to Outdoor Installations. In the interior of a one-family dwelling or in the interior of another building or structure associated with a one-family dwelling, any of the wiring methods recognized in Chapter 3 of this Code that contain a copper equipment grounding conductor that is insulated or enclosed within the outer sheath of the wiring method and not smaller than 12 AWG shall be permitted to be used for the connection to motor, heating, and control loads that are part of a self-contained spa or hot tub or a packaged spa or hot tub equipment assembly. Wiring to an underwater light shall comply with 680.23 or 680.33.
The equipment grounding conductor for the pool light is required to be insulated and not smaller than a #12. The spa requires a copper equipment grounding conductor that is not smaller than a #12.
I can’t see where the equipment grounding conductor that is already existing complies as is and would not comply to the new spa.

Mike