Let's break down these questions about conduit connections and grounding. We'll assume we're talking about rigid metal conduit (RMC) or intermediate metal conduit (IMC) as these are the most common scenarios for grounding locknuts.1. There is no bushing for these? It depends on the situation. Bushings are used to protect conductors from abrasion as they enter and exit conduit. Small conduits (like 1/2", 3/4")

Often, a plastic or insulated throat is built into the fitting itself (the connector or coupling). So, you might not need a separate bushing. Some connectors have a smooth, rounded opening that minimizes the risk of abrasion.

Larger conduits (1" and larger)

Especially when pulling larger conductors, a bushing is almost always required. The edge of the conduit is sharp and can easily damage the insulation on the wires. These bushings can be plastic or metal. They thread onto the end of the conduit.

Grounding bushings

There are also grounding bushings. These have a screw or lug to attach a grounding wire to the conduit. They provide a better grounding connection than relying solely on the locknuts.

In short

Look at the design of the connector you're using. If it has a smooth, rounded throat, you might not need an additional bushing for smaller conductors. But for larger conductors, or if the connector doesn't have a built-in throat protector, a bushing is necessary.

2. You would not use a grounding bushing but a grounding locknut as shown? Not necessarily. You can use both! Grounding Locknut

A grounding locknut is the basic method for ensuring the conduit is electrically connected to the enclosure (e.g., a panel box). It bites into the metal of the enclosure to create a good electrical bond.

Grounding Bushing

A grounding bushing (often called a "grounding wedge" or "insulated grounding bushing") adds another layer of grounding protection. It has a lug to which you can connect a grounding conductor (wire). This wire then gets connected to the grounding system of the panel or equipment.

When to use which



Grounding Locknut (Essential)

Always use a grounding locknut when connecting RMC or IMC to an enclosure containing electrical equipment.

Grounding Bushing (Recommended/Required)

Grounding bushings are highly recommended, especially in these situations:

Service entrance

Grounding bushings are typically required at the service entrance where the conduit enters the building's main panel.

Conduits containing large conductors

Larger conductors carry more fault current, making a robust grounding connection more critical.

Sensitive equipment

For equipment that's sensitive to electrical noise or requires very reliable grounding, a grounding bushing provides an extra margin of safety.

If there is a concentric knockout

This is where there is more than one layer of metal to break through, using just a grounding locknut may not be sufficient.

You can often use both a grounding locknut AND a grounding bushing. The grounding locknut goes on first (inside the enclosure), followed by the grounding bushing (on the outside of the enclosure, with the lug for the grounding conductor).3. You would need to remove regular locknut it comes with and buy a grounding locknut separately? Yes, that's correct. The standard locknut that comes with a connector is not a grounding locknut. You will need to purchase grounding locknuts separately. Make sure they are the correct size for the conduit and compatible with the type of enclosure you are connecting to. The grounding locknut has teeth or serrations that dig into the metal enclosure to provide a good electrical connection.

In summary

1. Determine if you need a separate bushing based on the size of your conduit, the size of your conductors, and the design of your connector. Larger conductors always benefit from a bushing.
2. Always use a grounding locknut. Consider adding a grounding bushing for enhanced grounding, especially at the service entrance, with larger conductors, or for sensitive equipment.3. Remove the standard locknut and replace it with a proper grounding locknut.

Important Safety Note: Electrical work can be dangerous. If you're not comfortable working with electricity, hire a qualified electrician. Always follow the National Electrical Code (NEC) and local electrical codes. Flag for review