Okay, let's break down the grounding/bonding requirements for meter enclosures and why you're running into inspection issues. This can be a confusing area because interpretations can vary.

The Core Issue: Bonding the Meter Enclosure

The fundamental goal is to ensure the meter enclosure itself is properly bonded to the grounding electrode system. This provides a low-impedance path for fault current back to the source, allowing the overcurrent device (breaker or fuse) to trip and clear the fault. This is crucial for safety.

Why a Bonding Bushing Should Work (in most interpretations)



GRC Nipple as a Conduit

Galvanized Rigid Conduit (GRC) is an approved grounding/bonding conductor when installed properly. A GRC nipple, especially if relatively short, is generally considered part of the conduit system.

Bonding Bushing's Role

The bonding bushing, when properly installed on the GRC nipple entering the meter enclosure, should provide a reliable connection between the GRC conduit and the enclosure. The bonding jumper from the bonding bushing to the grounding electrode system (or to the neutral if permitted by local rules) then bonds the enclosure via the GRC nipple.

Theory

In this scenario, the GRC nipple becomes the grounding conductor for the enclosure.

Why You Might Be Failing


Local Interpretation/Code Enforcement

Inspectors have some latitude in interpreting the NEC. Some jurisdictions have very specific preferences for how they want meter enclosures bonded, even if the code technically allows for other methods. This is the most likely reason for your failure. They might consider the bonding bushing on the nipple "indirect" bonding and want a more positive/direct connection. Denver is known for having these extra nuances.2.

Inspector Concerns About Reliability

An inspector might be concerned about the long-term reliability of the connection. A nipple could corrode over time, or loosen, creating a high-impedance path. A direct jumper is often seen as a more robust solution.3.

Specific Language in Local Amendments

Many municipalities amend the NEC. They might have specific wording about meter enclosure grounding/bonding that is stricter than the NEC itself.4.

Improper Installation of Bonding Bushing

Ensure the bonding bushing is properly torqued and making good contact with the GRC nipple and the enclosure. A loose or poorly installed bonding bushing defeats its purpose. Use oxide inhibiting compound.5.

Improper Locknuts

Make sure you have locknuts on both sides of the can and the inside locknut is tight against the can. I have seen installations with the can "sandwiched" between the locknuts. This could be interpreted as a "loose" connection.

Why the Neutral Bond Removal

This is related to the grounding/bonding arrangement. In most situations, the neutral conductor is only bonded to the grounding electrode system at one point, typically at the service disconnect.

Preventing Parallel Paths

If the neutral is bonded at multiple locations, it creates parallel paths for neutral current. This can lead to circulating currents and potentially energizing metal enclosures.

Meter Enclosure as a Service

Because the meter enclosure is often considered the "service equipment" (even if the actual service disconnect is further downstream), it's common to remove the neutral bond that might be factory-installed in the meter enclosure to avoid that multiple bonding scenario.

Local Utility Requirements

The utility company often has very specific requirements about where the neutral is bonded. They may dictate that only the utility transformer neutral is bonded.

What You Should Do (to avoid future re-inspections)


Talk to the Inspector Directly

The best approach is to have a direct conversation with the inspector. Politely ask for clarification on exactly what they want to see to pass inspection. Get specific details (e.g., "Do you require a bonding jumper from the meter enclosure to the grounding electrode conductor, even with the bonding bushing on the GRC nipple?"). Ask for the specific code section they are citing, if possible.2.

Contact the Electrical Inspection Department

If you can't get a clear answer from the inspector, call the main electrical inspection department for Denver. Ask to speak to a senior inspector or supervisor. Explain the situation and ask for guidance on their preferred method for bonding meter enclosures. Get it in writing if possible (an email would suffice).3.

Review Local Amendments

Find and carefully review the local amendments to the NEC for Denver. These are often available online through the city's website. Pay close attention to any sections related to grounding and bonding, service equipment, and meter enclosures.4.

Document Everything

Keep detailed records of your conversations with inspectors, any code references, and the methods you've used for bonding. This will help you in future inspections and can be useful if you need to appeal a failed inspection.5.

Consider Using a Bonding Jumper (Even if you think it's redundant)

In the long run, adding a bonding jumper from the meter enclosure to the grounding electrode system (or the neutral if locally permitted) might be the simplest way to avoid further issues. It provides a direct and easily verifiable connection.

Example of the Jumper Solution

After installing the GRC nipple with the bonding bushing, run a separate bonding jumper (typically green insulated wire, sized according to NEC Table 250.102(C)(1)) from a grounding lug inside the meter enclosure to:

Option A (Most Common)

The grounding electrode conductor (the wire connecting to the ground rod or other grounding electrode).

Option B (If Permitted Locally)

The neutral conductor, but only if allowed by the utility and the local electrical code.

Important Considerations



Utility Company Approval

Before making any changes to the service equipment, especially regarding the neutral connection, check with the utility company. They often have specific requirements about what you can and cannot do.*

AHJ Authority: Remember, the Authority Having Jurisdiction (AHJ) – which is the local electrical inspector or the electrical inspection department – has the final say on what passes inspection.By following these steps, you should be able to resolve the inspection issue and avoid future problems. Good luck! Flag for review