Building safety regulations require the installation of emergency lights not only inside the building, but outside the building on walkways leading away from egress points, to public ways of safe assembly points. Like any other exterior lighting, this poses a special challenge in having lights installed that are not affected by the weather.
There are two categories of installation defined when talking about exterior emergency lights; they are called:
While many people lump these two together as “waterproof emergency lights” it really isn’t an accurate description. The term “waterproof” refers to something that can be submerged in water, without any water leaks, such as a submarine. While these lights might be able to handle submersion for short periods of time, they really aren’t designed for that.
Wet locations for exterior lighting would be any place where the lighting unit is subject to complete saturation with water, such as areas where water can fall directly upon the light. This is the majority of exterior applications. These lighting units are protected from water entrance by rubber seals and gaskets.
Damp locations for exterior lighting are those areas that have some protection from direct saturation with water. This protection can come from a canopy, cantilevered overhang of the building, marquee or roofed over entryway. In these cases, the units my still become damp, but will not have water falling directly upon them. For this reason, the sealing of these units is not as stringent as that for wet location lights.
While water is the main weather consideration for emergency lights mounted on the exterior of your building, it is not the only one. Temperature, especially cold, can negatively affect the performance of any battery, reducing its current holding capacity and its current release rate.
In regions where freezing cold temperatures are experienced, it is necessary to provide for protection of your exterior emergency lights from cold. This is accomplished by adding a “cold weather package.” This option is essentially a small heater, which maintains the internal temperature of your lighting units at a temperature above freezing.
It is important to maintain the water tight integrity of your exterior emergency lighting units. When installing, be sure to use watertight connections for electrical cables or conduits entering the unit. This is a normal consideration for all exterior electrical connections, so your electricians should provide these connections as a normal part of their installation.
When performing your annual inspection of your emergency lights, you are required to open the case of the unit to test the battery and charging circuit voltages and visually inspect the connections for corrosion. Keep in mind that a wet or damp environment increases the opportunity for corrosion. If you are experiencing corrosion on your battery connections, it could indicate a break in the seal. In any case, inspect all seals, and clean them if they are dirty, to insure the waterproof integrity of your lighting units.
Weatherproof emergency lights have improved in recent times. Fluorescent lamps have been adapted to weatherproof emergency lights, which allows the fixture to be more efficient and for the lamps to have a longer useful life. Since fluorescent tubes put out twice as much light as a conventional incandescent lamp, while using the same amount of electricity, efficiency improves. This allows weatherproof emergency lights to feature smaller, more powerful emergency light batteries.
The type of battery referred to is nickel cadmium. Nickel cadmium emergency light batteries are available on a number of weatherproof emergency lights that are offered. Some weatherproof emergency lights can come with nickel metal hydride (NiMh) batteries, which are even more efficient than nickel cadmium. For wet locations, choose a nickel cadmium or nickel metal hydride emergency light battery for waterproof emergency lights - reduce maintenance in hard to reach, wet environment installation areas.