Emergency lighting in stores, hospitals, passages, stairwells, and basements have become so common we scarcely give it a thought. When a building experiences a power outage, some lights stay on thanks to back-up battery power. The earliest ones used incandescent bulbs that glowed dimly. Nowadays we benefit from high luminosity floodlights. Indeed, some halogen fittings are as bright as auto headlights.
Battery Types for Emergency Lighting and Signs
Early emergency lights connected to a separate grid taking power from lead-acid battery banks. Transistors or relay technology sensed when a power outage started, and turned on the auxiliary emergency lighting.
As technology became more energy efficient, it became possible to fit lower-voltage batteries in the light fittings themselves.
Emergency lighting batteries are rechargeable. The power runs through them to the device, in much of the same way as starter batteries. There are two main types in common use, namely nickel-cadmium, and the sealed lead-acid ones we supply. When replacing these, it’s essential to stay with the same battery size, type, and voltage rating.
The ‘Rules’ for Positioning Emergency Light Fittings
Building bylaws generally require that all commercial and high-density buildings have emergency lighting. Its main function is to help occupants find their way to emergency exits and staircases.
Some emergency egress lights stay on until a technician presses a reset button. Others turn themselves off when mains power restores.
Different cities like Los Angeles, New York, Chicago, etc all have their own detailed standards.
Power Sources for Emergency Egress Lighting
Most emergency lights run off separate circuit breakers. In some instances though, they still connect to battery banks that hold full charge until an outage starts. Wires feeding electricity to emergency lighting are usually separate harnesses with fire-resistant properties.
Related
What is a Nickel Cadmium Battery?
How Sealed Lead-Acid Batteries Work
Preview Image: People Escaping
