Final answer:
A separately derived system for a premises wiring system is powered from a source other than a service entrance. Examples include backup generators and solar power systems with battery storage.
Step-by-step explanation:
A separately derived system for a premises wiring system is powered from a source other than a service entrance.
This means that instead of being connected directly to the main power grid, the system obtains its power from an alternative source, such as a generator or battery backup.
One example of a separately derived system is a backup generator for a building. In the event of a power outage, the generator automatically starts and provides electricity to essential circuits in the building. This allows critical systems, such as emergency lighting or medical equipment, to continue functioning despite the disruption to the main power supply.
Another example is a solar power system with battery storage. The solar panels generate electricity during the day, which is used to power the building directly. Excess electricity is stored in batteries, which can be used to provide power during nighttime or when the sun is not shining.