The best thing to do when you are not sure how to define an assembly or a piece of equipment is to locate the UL marking and listing. Even if the product is investigated and tested per one of the other NRTL, it will have to meet a particular standard.
For your particular instances, look for UL 1795. This would mean the tub assembly is listed as a hydrotub. Once you know that, then you can apply the requirements of Part VII of Article 680 and the UL guideinfo use and installation requirements.
In my opinion, no bonding is required per your description of the installation.
Last edited by BPHgravity; 05/22/08 11:22 AM.