I did not see in your post WHERE the spa was located? That is VERY important. You are possibly talking about two different wiring methods. Forget about using SE cable. What is this THHN cable you are talking about? Multi-Conductor Cable for a cable tray or conduit?
What is your experience level? Are you licensed at all?
Spas are tricky and expensive to wire up.
There is more to this than you may have first thought.
[This message has been edited by mustangelectric (edited 11-22-2004).]
Electricity has no respect for ignorance!