Okay, let's break down whether those short RGS (Rigid Galvanized Steel) conduit sections need to be bonded in your scenario.

Understanding the Relevant Concepts Bonding

Bonding creates a low-impedance path for fault current to return to the source, allowing overcurrent protective devices (circuit breakers or fuses) to trip and clear the fault quickly. This minimizes the risk of electrical shock and fire.

Grounding Electrode Conductor (GEC)

Connects the electrical system (typically the neutral) to a grounding electrode (e.g., ground rod, water pipe).

Equipment Grounding Conductor (EGC)

The conductor that connects the metal parts of electrical equipment (like cabinets and conduit) back to the grounded conductor (neutral) at the source. RGS conduit itself can serve as the EGC if properly installed.

Rigid Galvanized Steel (RGS) Conduit

A type of metal conduit.

Fiberglass/PVC Conduit

Non-metallic conduit.

Analysis of Your Situation

Here's a breakdown of the key factors:1. RGS Conduit as the EGC



Potential

The short sections of RGS conduit can serve as part of the EGC system if properly connected. This is the most likely reason they are there.

Requirement

If the RGS conduit is intended to be part of the EGC path, it absolutely must be properly bonded at both ends.2.

The Critical Question: Is the RGS Conduit Intended to be the EGC? This is the core issue. You need to determine the intent of the original design. Look for Clues

Are there grounding bushings/hubs installed on the RGS conduit where it enters the cabinets? These would be a very strong indicator that the RGS is intended as the EGC. Is there a grounding conductor (wire) running inside the fiberglass/PVC conduit and connected to the RGS at both ends? Are the cabinets themselves properly grounded? (More on this below).3.

Cabinet Grounding

The electrical cabinets must be grounded regardless. If the RGS conduit is not intended to be the EGC, the cabinets would need to be grounded via another method (e.g., a wire EGC).

Reasons Why Bonding Would be Necessary Safety

If the RGS conduit could become energized due to a fault (even indirectly), it needs to be bonded to provide a low-impedance path back to the source for fault current.

NEC Compliance

The NEC requires metal conduit to be properly bonded to ensure the integrity of the grounding system.

Reasons Why Bonding Might Not Be Absolutely Required (But Still a Good Idea) Completely Isolated System

Highly Unlikely. If the electrical system is designed such that the RGS conduit cannot become energized in any way, shape, or form, and the cabinets are grounded by a separate, dedicated EGC, then technically bonding the short RGS sections might not be strictly required by code. However, this is a very difficult case to argue and demonstrate, and it's generally not worth the risk.

Recommendations1. Consult the Original Design/Engineer

The best course of action is to consult the original electrical design drawings and/or speak with the engineer who designed the system. They can tell you definitively whether the RGS conduit was intended to be part of the EGC.2.

Assume Bonding is Required

Unless you have absolute certainty otherwise, err on the side of caution and bond the RGS conduit sections. It's far better to be safe than sorry.3.

Proper Bonding Methods



Grounding Bushings/Hubs

Use grounding bushings or hubs specifically designed for bonding conduit to enclosures. Make sure they are properly tightened.

Bonding Jumpers

If grounding bushings/hubs aren't feasible, use bonding jumpers (grounding conductors) to connect the RGS conduit to the cabinet. Use appropriately sized conductors and approved connectors.4.

Inspect Existing Connections

If the RGS conduit is intended to be part of the EGC, carefully inspect all existing connections for tightness and corrosion.

In Summary

It is highly probable that the short RGS sections are intended to be part of the EGC system and need to be bonded. Consult the original design if possible, but if in doubt, bond the RGS conduit to the cabinets using appropriate methods. This will ensure the safety and integrity of the electrical system. When in doubt, reach out to a qualified electrical engineer for guidance. Flag for review