What occurs when the main power is available in the emergency lighting circuit?

When the main power is available in the emergency lighting circuit, the relay coil is energized. This means that the presence of the main power supply activates the relay, which is responsible for controlling the power flow to the emergency lighting.

In this state, the relay closure typically allows normal lighting functions to occur. The energized relay ensures that the circuit can direct power to the appropriate lights as intended under normal conditions. In the event of a power failure, the relay would de-energize, switching the circuit over to the emergency power supply, thus enabling the emergency lighting system to operate independently.

It is important to understand the roles of the components involved; the effective functioning of the emergency lighting system is contingent upon the relay's operation. Thus, when mains power is present, the system behaves in a way that facilitates normal lighting, evidenced by the relay coil being energized, which allows the circuit to function correctly.