Emergency lighting purposes and trickle charging

Main purposes of emergency lighting in industry

Emergency lighting is lighting that comes on automatically when the normal lighting fails. Its purposes are:

1. Safe evacuation: light the escape routes, stairs and exits so people can leave quickly without panic.
2. Show exits and direction: illuminated exit signs and direction arrows.
3. Locate safety equipment: fire extinguishers, fire alarm call points, first-aid boxes.
4. Safe shutdown of processes: operators can stop machines, close valves and shut down furnaces safely (standby/high-risk task lighting).
5. Prevent accidents and panic in areas with moving machinery, open pits or hazardous chemicals.
6. Help rescue and fire-fighting teams.
7. Meet legal and fire safety codes (minimum ≈ 1 lux on the escape route floor, for 1–3 h).

Trickle charging method

Trickle charging keeps a standby battery fully charged by supplying a small continuous current equal to its self-discharge loss.

• The current is about 1% of the Ah capacity or less (for a healthy battery, as little as about 1 mA per Ah).
• The charger (step-down transformer, rectifier and series resistance or regulator) is permanently connected to the battery.
• The battery normally does not feed the load; it supplies the emergency lights only when the mains fails, after which a normal/boost charge is given and then trickle charging resumes.
• Used for emergency lights, fire alarm panels, engine-starting and switchgear batteries.
• The current must be set correctly: too high → gassing and water loss; too low → sulphation.

 AC ─►[Transformer]─►[Rectifier]─►[R]─► + Battery −
                                     │
                       Emergency lamps (on mains fail)