You're right to consider this. Grounding with EMT conduit requires careful attention to ensure a low-impedance fault path back to the source. Here's a breakdown of your options when using set-screw or compression EMT connectors and needing to add a grounding bushing (or similar) for enhanced grounding

Options for Adding Grounding to EMT Systems:
Separate Grounding Bushing

This is the most common and generally preferred method for larger conduit sizes or where robust grounding is required.

How it works

You install a grounding bushing after the EMT connector on the end of the conduit where it enters the enclosure. The bushing has a lug for attaching a grounding conductor (typically a bare copper wire). This conductor is then connected to the enclosure's grounding bus or grounding electrode system.

Pros

Excellent grounding path, especially with properly sized grounding conductors. Readily available. Allows for easy inspection and maintenance. Required for service entrance raceways.

Cons

Requires an additional component (the grounding bushing itself). Adds a step to the installation.

Connector with Integrated Grounding Lug

These are EMT connectors (either set-screw or compression) that have a grounding lug built into the connector body.

How it works

The connector is installed as usual, and then a grounding conductor is attached to the lug and connected to the enclosure's grounding bus or grounding electrode system.

Pros

Fewer parts – the connector and grounding connection are combined. Potentially faster installation. Compact.

Cons

Potentially less robust grounding than a separate grounding bushing, especially if the lug is small or the connection to the connector body is not very substantial. May be less readily available, especially for larger conduit sizes. The quality of the connection between the lug and the conduit can vary depending on the manufacturer.

When do you need the grounding bushing (or similar) at all?

The NEC (National Electrical Code) doesn't always explicitly require a grounding bushing, but it does require effective grounding. Grounding bushings are typically needed when: Service Entrance

At the service entrance (where power enters the building), NEC 250.92(B) generally requires bonding jumpers (connected via grounding bushings or similar) to ensure a low-impedance path to ground.

Concentric Knockouts

When using concentric or eccentric knockouts in enclosures, the continuity of the grounding path can be compromised. A grounding bushing/jumper helps bridge this gap.

Oversized Knockouts

If the knockout is significantly larger than the conduit size, it can create a high-impedance ground path.

To improve grounding in general

Even if not strictly required by the NEC in all situations, adding a grounding bushing (or a connector with a grounding lug) can improve the overall grounding system. A superior ground is always preferred.

Key Considerations for Both Options



UL Listing

Ensure that all connectors and grounding bushings are UL-listed or otherwise approved for the intended use. This ensures they meet safety and performance standards.

Conductor Size

Use the correct size grounding conductor for the equipment grounding conductor according to NEC 250.122.

Tight Connections

Make sure all connections (connector to conduit, grounding conductor to lug, lug to enclosure) are clean, tight, and free of corrosion. Use anti-oxidant joint compound if necessary.

Installation

Follow the manufacturer's instructions for installing the connectors and grounding bushings.

Material Compatibility

Use connectors and bushings made of materials compatible with the conduit (e.g., steel connectors with steel EMT).

In summary:

While a connector with a grounding lug can be convenient, a separate grounding bushing* is generally preferred for better grounding performance, particularly at service entrances or where concentric/eccentric knockouts exist. Always comply with the NEC and local codes, and prioritize a robust and reliable grounding system. When in doubt, consult with a qualified electrician or electrical inspector. Flag for review