Emergency Light

An emergency light is a battery-backed lighting device that comes on automatically when a building experiences a power outage. Emergency lights are standard in new commercial and high occupancy residential buildings, such as college dormitories. Most building codes require that they be installed in older buildings as well. Early battery backup systems were huge, dwarfing the size of the lights for which they provided power. The systems normally used lead acid batteries to store a full 120-volt charge. For comparison, an automobile uses a single lead acid battery as part of the ignition system. Simple transistor or relay technology was used to switch on the lights and battery supply in the event of a power failure. The size of these units, as well as the weight and cost, made them relatively rare installations. As technology developed further, the voltage requirements for lights dropped, and subsequently the size of the batteries was reduced as well. Modern lights are only as large as the bulbs themselves - the battery fits quite well in the base of the fixture.

As a method of signaling a power outage, some models of emergency lights must be shut off manually after they have been activated. This is true even if the main building power comes back on. The system will stay lit until the reset button on the side of the unit is pressed. Emergency lighting is often referred to as egress lighting. Emergency lights are used in commercial buildings as a safety precaution to power outages, so that people will be able to find their way out of a building. Exit signs are often used in conjunction with emergency lighting.

A glow stick is a single-use translucent plastic tube containing isolated substances which when combined are capable of producing light through a chemical reaction-induced chemoluminescence which does not require an electrical power source. The dyes used in glow sticks usually exhibit fluorescence when exposed to ultraviolet radiation. Therefore even a spent glow stick will shine under a black light.

Glow sticks contain hydrogen peroxide, and phenol is produced as a by-product. Therefore, it is advisable to keep the mixture away from skin, and to prevent accidental ingestion, if the glow stick case splits or breaks. If spilled on skin, the chemicals could cause slight skin irritation, and swelling or, in extreme circumstances, cause vomiting and nausea. However, many ravers will cut or break open a glow stick and apply the glowing solution directly to bare skin in order to make their bodies glow. It has been said that glow stick chemicals cause cancer, although no research has suggested that they might. Also it is wise to avoid all contact with thin membranes such as the eye or nasal area. Despite reports to the contrary, it is not safe to smoke or ingest glowing phenol, and it will not produce any drug-like effects. The fluid contained in glow sticks can also dissolve some types of plastic.