You've touched on a very common and debated point in electrical installations. Here's a breakdown to help clarify the requirements

Yes, a metal pull box with PVC conduit entering and exiting generally needs to be bonded, even if only feeders are passing through, and there are no splices or terminations within the box.

Here's the reasoning based on the NEC (National Electrical Code), which is the standard most jurisdictions in the US follow: NEC 250.86 Other Enclosures

This section is a key part of the puzzle. While it speaks of enclosures likely to become energized it can be interpretated as a pullbox.

Why Bonding is Required (Even Without Splices/Terminations)



Fault Current Path

In a fault condition (a short circuit), the metal pull box can become energized. A properly bonded pull box provides a low-impedance path for fault current to return to the source (transformer or generator). This allows the overcurrent protective device (circuit breaker or fuse) to quickly trip, clearing the fault and minimizing the risk of shock or fire. Even without splices or terminations inside the box, the conductors passing through the box can create a capacitive coupling effect that could energize the enclosure under fault conditions, or through general breakdown of wire insulation over time.

Safety

The goal of bonding and grounding is to provide a safe environment. Even if the risk of the pull box becoming energized seems low, the potential consequences of a fault are high. Bonding helps to ensure that any exposed metal parts are at or near ground potential, reducing the risk of electric shock.

How to Bond

The bonding jumper must be sized according to NEC 250.102(C) based on the size of the ungrounded conductors (feeders) passing through the pull box.

Why the Confusion/Conflicting Answers



Interpretation

Some electricians and inspectors interpret the NEC requirements for bonding enclosures more narrowly, focusing on enclosures that contain electrical connections (splices, terminations, devices). They may argue that a simple pull box with only pass-through conductors doesn't technically meet the criteria.

Old Habits

In older installations or areas with less strict enforcement, bonding of simple pull boxes might have been overlooked.

Local Amendments

Local jurisdictions may have specific amendments to the NEC that affect bonding requirements. Always check local codes.

Important Considerations



Size of the Feeders

Larger feeders pose a greater risk of fault current and require larger bonding jumpers.

Conduit Material and Size

While you have PVC conduit entering and exiting the pull box, the size and number of conduits can influence the overall grounding effectiveness.

Consult with a Qualified Electrician and Inspector

The best course of action is to consult with a licensed electrician and your local electrical inspector. They can provide specific guidance based on your installation and local requirements.

In summary: While you're getting conflicting answers, the safer and more compliant approach* is to bond the metal pull box, even with only PVC conduit and pass-through feeders. It provides an extra layer of safety in the event of a fault. Bonding is a relatively inexpensive and easy process, and it's generally better to err on the side of caution when it comes to electrical safety. Always prioritize the safety of people and property. Flag for review