Okay, this is a common situation with generator installations and pool wiring. You're right to be concerned about the SER cable and the potential for ground loops. Here's a breakdown of the issue, potential solutions, and things to consider

Understanding the Problem
The Rule

The NEC (National Electrical Code) requires that swimming pool equipment be fed from a separately derived system with an insulated equipment grounding conductor run with the circuit conductors. This is designed to prevent stray currents from causing shock hazards in and around the pool.

SER Cable Issues

SER (Service Entrance Cable) typically has a bare aluminum or copper conductor spiraled around the insulated conductors. This bare conductor is often used as both the neutral and the ground in a service entrance application. However, this is not allowed for feeding pool equipment from a subpanel after an ATS. The reason is that the neutral and ground are bonded in the main panel, and running a combined neutral/ground like that after the main panel creates a parallel path for neutral current. This is the recipe for circulating current, ground loops, and potentially dangerous voltage on the grounding system near the pool.

ATS and the Subpanel Issue

When a generator with an ATS (Automatic Transfer Switch) is installed, your main breaker panel essentially becomes a subpanel when the generator is running. This is because the neutral connection is often switched during the transfer (some ATS designs vary), and the ground and neutral are bonded at the generator. This makes that connection a separately derived system during generator operation.

Why the Inspector Might Not Catch It

Inspectors are human, and things can be missed, especially in complex setups. More importantly, even if they miss it initially, a ground fault or a shock incident could expose the issue later, with significant legal and safety consequences.

Why It Matters

Even if the inspector doesn't see it, and even if everything seems to work, having a shared neutral/ground is creating a potential safety hazard, especially around a pool where people are barefoot and wet.

Potential Workarounds (and their limitations)

Unfortunately, there isn't a perfect "workaround" that fully complies with the NEC without replacing the SER cable. Here are some options, ranked by their level of compliance and safety, along with their drawbacks:1. Replace the SER Cable with a 4-Wire Cable (Best and Recommended Solution)

This is the correct and safest solution. Replace the SER cable feeding the main breaker panel from the ATS with a 4-wire cable (e.g., THHN/THWN in conduit, or appropriate underground feeder cable). This cable needs a dedicated, insulated equipment grounding conductor (green or bare) separate from the neutral (white).

Pros

Full NEC compliance, eliminates ground loop potential, provides the highest level of safety.

Cons

Most expensive and time-consuming option. May require opening walls or digging trenches depending on the cable route.2.

Run a Separate, Dedicated Grounding Conductor (Potentially Compliant, Needs Careful Execution)

You could leave the SER cable in place but add a separate, insulated equipment grounding conductor (green or bare copper) alongside the SER cable. This conductor must be sized appropriately for the circuit and bonded to the grounding electrode system at both the ATS (generator) location and the main panel.

Pros

Less invasive than replacing the entire cable.

Cons

This can be compliant but needs to be approved by the inspector, and it may not be easy to install the added ground wire if the SER cable is buried without conduit. Sizing the ground wire correctly is critical. It must be sized based on the overcurrent protection device (breaker or fuse) protecting the circuit. You still have a parallel neutral return path with the bare SER ground/neutral, but the separate ground wire gives you an alternative. This may be acceptable to the inspector, but discuss it with them beforehand.

Important Considerations



Bonding

Ensure proper bonding at both ends.

Accessibility

The added ground conductor needs to be accessible for inspection.

Potential for Noise

The SER cable could still introduce some noise into the grounding system.3.

Using a Ground Fault Circuit Interrupter (GFCI) Breaker (Mitigates Hazard, Not a Replacement)

A GFCI breaker at the origin of the pool equipment circuits will provide a degree of safety by detecting small ground faults and tripping the circuit. However, this is not a substitute for proper grounding. It's a safety net, not a primary solution.

Pros

Adds a layer of safety. Relatively inexpensive.

Cons

Doesn't address the underlying ground loop issue. GFCI breakers can nuisance trip if there are even slight ground currents.

NEC Compliance

The NEC requires GFCI protection for many pool equipment circuits, but it doesn't allow it as a replacement for proper grounding.4.

Do Nothing (NOT RECOMMENDED - Dangerous)

Leaving the SER cable as-is and ignoring the issue is the worst option. It creates a potential shock hazard that could result in serious injury or death. It's also a code violation.

Key Considerations and Steps to Take



Consult with a Licensed Electrician

This situation requires the expertise of a licensed electrician who is familiar with the NEC and local codes. They can assess your specific setup, determine the best course of action, and ensure the work is done safely and correctly.

Talk to the Inspector

Before doing any work, discuss your situation and proposed solution with the electrical inspector. They have the final say on what is acceptable in your jurisdiction. It's better to get their approval upfront than to face rejection later.

Document Everything

Keep records of all work performed, materials used, and inspections conducted. This documentation can be crucial in the event of a future issue.

Safety First

Always prioritize safety when working with electricity. If you are not comfortable or experienced, hire a qualified electrician.

In summary, while there might be some limited options, the most reliable and safest solution is to replace the SER cable with a proper 4-wire cable. It is worth the cost and effort to ensure the safety of yourself and others around the pool. Flag for review