Journeyman Electrician Practice Exam

When a size 4 AWG or larger insulated conductor enters a panelboard, what must be provided?

1. An insulated bushing

2. A grounded connection

3. A conduit body

4. A junction box

The correct answer is: An insulated bushing

When a size 4 AWG or larger insulated conductor enters a panelboard, the requirement is for an insulated bushing. This is essential in order to protect the insulation of the conductor from damage as it passes through the panelboard's knockout. An insulated bushing provides a smooth surface for the conductor to make contact with, minimizing the risk of abrasion or wear on the insulation. This helps ensure the safety and longevity of the electrical installation. While the other options may relate to various aspects of electrical installations, they do not address the specific requirement regarding the protection of conductors entering a panelboard like an insulated bushing does. Grounded connections, conduit bodies, and junction boxes each serve specific purposes in electrical systems but are not mandated purely for the entry of large insulated conductors into a panelboard.