A separately derived system is a premises wiring system that is _____.

• A. Fed from the main service panel
• B. Powered from a source other than a service
• C. Connected in parallel to the building system
• D. Utilized for high voltage applications

Answer: (B)

A separately derived system is defined as a premises wiring system that is powered from a source other than the building’s main service. This means that the electrical source for the system is independent and does not derive any of its power from the main electrical service feeding the building. This characteristic is crucial as it allows the separately derived system to operate independently, providing flexibility and isolation from the main power source.

This separation is particularly important for systems that may need to supply power in a specific environment, such as in industrial settings, where there may be distinct grounding requirements or safety concerns that necessitate not sharing grounds or conductors with the main service. By being independently sourced, the system can also help to mitigate the risk of electrical faults affecting both the main service and the derived system.

Understanding this concept is important for various applications, including uninterruptible power supplies (UPS), isolated generators, and renewable energy sources that may power specific equipment without interfering with or relying on the main service panel.