Yes, you're absolutely right! What you're thinking of is called a bushing. Specifically, an insulated bushing or insulated throat bushing.Here's why and what they do: Purpose

When you terminate conduit (threaded or unthreaded) into a metal junction box (J-box), the cut end of the conduit can have sharp edges, even if reamed. These edges can damage the insulation of wires as you pull them through, leading to shorts, ground faults, and potential fire hazards.

How they work

Insulated bushings are installed onto the end of the conduit that is entering the box. They provide a smooth, rounded, and insulated surface for the wires to slide against during the pulling process, preventing damage to the insulation.

Types



Plastic/Nylon Bushings

These are the most common and generally less expensive.

Metal Bushings with Plastic/Insulated Liners

These offer more durability and are often used for larger conduit sizes or in harsher environments.

NEC (National Electrical Code) Requirements

The NEC often requires the use of insulated bushings, especially when dealing with conductors sized #4 AWG or larger. However, regardless of wire size, it's generally good practice to use them for any wiring entering a metal enclosure to protect the insulation.

Installation

They typically thread onto the conduit end inside the box after* the conduit is secured to the box. Some are a simple push-on type, especially for smaller conduit sizes.

Key Takeaway

So, yes, you're correct! An

insulated bushing is the part you're looking for. It's a critical component for protecting wire insulation and ensuring safe and reliable electrical installations. Using them is a best practice and often a code requirement. Flag for review