Separately Derived System

Definition

A separately derived system, as defined by the National Electrical Code Article 100, is a premises wiring system whose power is derived from a source of electric energy or equipment other than a service. Such systems have no direct electrical connection, including a solidly connected grounded circuit conductor, to supply conductors originating in another system.

Purpose

The purpose of a separately derived system is to provide an independent electrical power source for specific loads or applications, ensuring isolation from the main electrical supply and enhancing safety and reliability.

Examples of Use

• Backup generators that supply power to critical systems during outages are examples of separately derived systems.
• Transformers that change voltage levels and create isolated power systems for sensitive equipment.
• Uninterruptible power supplies (UPS) that provide temporary power during outages and protect against power surges.

Related Terms

• Transformer: A device that changes the voltage of an electrical power supply.
• Backup Generator: A secondary power source used when the main supply fails.
• Isolated Power System: An electrical system that is electrically separate from the main power source.

Notes

Separately derived systems are crucial for providing reliable and safe power to critical loads, ensuring continuity of service and protection against electrical faults.