Okay Tubman and all,
Finished mounting the spa box a little while ago. Per the wiring instructions, I ran the "line" wires (coming out of the slot in the back of the box) to the two line terminals. For the "load" wires to the spa (dropping into the conduit) I connected the red and black to the GFCI per the wiring diagram on the box cover panel, and the ground to the terminal on the right. The line ground was connected to a point inside the wall box by my contractor. The GFCI pigtail connects to the neutral bus on the left-hand side.
The question: Do I wire the two neutrals directly together and bypass the buses all together? Per the spasupport.com electrical guidance, it tells me not to wire the neutral from the spa to ANY terminal in the box unless the terminal is isolated from the ground. However, this bus is completely isolated from the ground bus on the other side of the box. Also, there is a "load neutral" terminal on the right-hand side of the GFCI. My inclination is to connect the spa neutral to the slot in the GFCI, and the line neutral coming from the house to the neutral bus (next to the "pigtail" coming from the back of the GFCI). I bought some large-diameter shrink tubing, so I could solder the neutrals directly together, and then slide the shrink tubing around the joint for a clean installation. Let me know what all you pros have to say.
Thanks!
Greg