You're asking about whether underground elbows in an electrical conduit system need to be GRS (Galvanized Rigid Steel) even if they're not the elbows that actually transition to above ground.Here's the breakdown and why you're likely correct: GRS for Physical Protection

The primary reason GRS is required underground is its superior resistance to corrosion and physical damage compared to other conduit types like EMT (Electrical Metallic Tubing). Underground environments are harsh, with moisture, soil chemicals, and the potential for physical stress from settling or excavation.

Elbows are Vulnerable

Elbows, by their nature, are points of stress and potential weakness in a conduit run. They are subjected to bending forces during installation and potentially over time. They also often have threaded connections, which are points where corrosion can initiate.

Inconsistency Creates Risk

If you were to use a different conduit type (like EMT) for an underground elbow that's connected to a GRS system, you've introduced a weak point. The less robust elbow could corrode or fail, compromising the entire system. It would defeat the purpose of using GRS elsewhere.

Code Considerations

While the specific wording of the electrical code (NEC in the US) can be interpreted differently, the intent is clear. If the entire underground run requires GRS for its environmental protection, then all components within that run must also meet the same standard. Think of it like a chain – it's only as strong as its weakest link.

Therefore, yes, your interpretation is generally correct. If the underground portion of a conduit system requires GRS, then the elbows within that underground portion should also be GRS, even if they aren't the ones directly transitioning to above ground.

Important Considerations



Local Amendments

Always check your local electrical codes and regulations. Some jurisdictions may have specific amendments that clarify or modify the NEC requirements.

Authority Having Jurisdiction (AHJ)

The AHJ (e.g., a local electrical inspector) has the final say on interpretations. If you have any doubt, consult with them directly.

Specific Applications

In very rare circumstances, there might be exceptions for specific applications (e.g., direct-buried rated PVC conduit encased in concrete). However, these are the exceptions, not the rule. This would not apply to GRS underground.

Manufacturer's Instructions

Always follow the manufacturer's installation instructions for the conduit and fittings being used.

In summary, to maintain the integrity and longevity of an underground GRS conduit system, all components, including elbows, should be GRS. Flag for review