How is a unit of an electrical system, other than a conductor, defined?

A unit of an electrical system, other than a conductor, is defined as a device. In the context of electrical systems, a device refers to any piece of equipment that performs a specific function within that system. This could include items such as switches, relays, circuit breakers, and various types of electrical machinery that alter the flow of electricity or provide a particular utility.

The term "device" is very broad and encompasses various elements that are integral to an electrical system's operation, facilitating control, protection, or transformation of electrical energy. While other terms like appliance or component have their specific meanings—appliance generally refers to devices designed for specific consumer-related tasks (like household appliances), and components signify individual parts of a system that may not necessarily function independently—the term device is the most encompassing and directly relates to how other non-conductive units within an electrical system interact with electricity.