This is a really good and important question. Electrical safety around pools is critical. While I am an AI and cannot provide official electrical code compliance advice, I can offer information that should help you have a more informed discussion with your contractor and local electrical inspector.

Here's a breakdown of the issues and considerations, based on general electrical safety practices (specifically around NEC 680), combined with standard pool construction practices


Understanding the NEC Requirements



Equipotential Bonding (NEC Article 680)

The purpose of equipotential bonding is to minimize voltage gradients in and around the pool, reducing the risk of electric shock. It creates a common electrical potential across all metallic elements.

Bonding Conductor

A solid copper conductor (typically #8 AWG) is used to bond all metallic parts.

Bonding Requirements for Metallic Pool Shells

Metal pool shells MUST be bonded. This is non-negotiable. You're correct in that the bonding ring should encircle the pool and connect to the shell at multiple points.

Bonding Requirements for Metallic Components

Any metal ladders, handrails, light niches, etc., must also be bonded to the equipotential bonding grid.

Concrete Encapsulation

NEC article 680.26(B)(2) goes over concrete encased electrodes and covers the requirements for bonding concrete with 1/2" steel or #8 solid bare copper.
2.

The Vermiculite Floor and Vinyl Liner



The Question

Your core question is whether the vermiculite floor needs to be bonded, given that it's: Porous and possibly conductive when wet. Covered by a non-conductive vinyl liner. In direct contact with the metal shell.

Here's why the vermiculite floor may not need to be bonded If the vermiculite is used to fill in imperfections and is not considered concrete, the requirements from NEC 680.26(B)(2) does not apply. The code makes no specific mention of the requirements for bonding of pool floors, only that the metal parts that constitute the pool are bonded together3. Addressing Your Concerns and Recommendations



Consult with a Licensed Electrical Inspector

This is the most important step. The local electrical inspector has the final say on what is required to meet code. Discuss your concerns with them, and ask for clarification on how they interpret the code in your specific situation. They may have specific requirements or interpretations based on local conditions.

Over-Engineering for Safety

While it might not be strictly required, consider the benefits of extra bonding. A copper grid placed within the vermiculite before the liner is installed could provide an extra layer of safety, even if not explicitly mandated by code. The cost of the copper grid is relatively low compared to the potential consequences of an electrical fault.

Documentation

Ensure that all bonding work is properly documented and inspected by the electrical inspector. Keep records of the materials used and the methods employed.

Trust, but Verify

Even if your contractor is experienced, it's always wise to independently verify that their methods align with best practices and local code.

In summary



Bond the metal pool shell without exception. This is a must. Bond all other metal components near the pool (ladders, handrails, light niches, etc.). Consult with your local electrical inspector to determine if bonding the vermiculite is required in your specific situation, considering the code and the materials being used. Consider adding a copper grid in the vermiculite for enhanced safety, even if not strictly required.* Prioritize electrical safety above all else. The cost of proper bonding is minimal compared to the potential consequences of a faulty electrical system around a pool.I hope this helps! Good luck with your pool project. Flag for review