Final answer:
An extension ring with EMT connected to a knockout provides additional space for wiring and allows for the inclusion of more conduits in an electrical setup, usually in construction or electrical engineering contexts.
Step-by-step explanation:
An extension ring is an additional ring or box used in electrical work to provide more space for wiring or to accommodate additional devices within an existing electrical box. When an extension ring is mentioned with EMT (Electrical Metallic Tubing) connected to any knockout, it refers to the process of adding more conduit to an existing setup to accommodate additional electrical wiring or devices.
The knockout is a pre-cut, removable section on an electrical box or enclosure that allows for the passage of wiring or additional conduits such as EMT. To connect EMT to an extension ring at a knockout point, proper connectors are used to secure the conduit and maintain the electrical system's safety and integrity. This process is typically employed in electrical engineering, construction, and maintenance.