There was a time when emergency vehicle lighting was a source of light backed by a battery or a generator system, which would go on automatically in case of a power failure or a fire. The most common uses were the “EXIT” signs in public places or small incandescent light bulbs that gave just enough light so one could carry out basic activities, like evacuate buildings in case of emergencies. The early backup power systems were gigantic, compared to the size of the lights they generated power for. Normally, the back-up power came from lead acid batteries storing 230 volts of charge. The size, weight, and cost of these systems meant they were limited in their use.
With the advent of technology, the need for enduring and brighter lights was recognized and greater focus was placed on creating lights that would provide more brightness and have the capability of illuminating larger areas. Here's where the light emitting diode (LED) comes in. While not a new technology to the 21st century, the earlier generations delivered relatively little light and so did not gain much popularity. It was not until the third generation, when they made available an effective source of lighting, that their popularity gained momentum for all kinds of emergency lighting situations.
The reason this new technology lend itself so well to emergency lighting, is because it contains absolutely no moving parts. There are no motor drives, no belts, and no chains; there is nothing mechanical to regulate, lubricate or wear out. What’s more, there aren’t even any bulbs! The LED is a diode - an electronic component that gives off light and lasts much longer than any bulb. Unlike in conventional bulbs, no heat is produced, so LEDs don’t wear out. Finally and most importantly, they use a fraction of the power compared to the traditional emergency lighting. This fact makes LED lights especially useful in applications of emergency vehicles, as the car’s battery is not drained and there is less probability of electrical system failures. LEDs are essentially self-contained. Since there are no nonessential hook ups, there are fewer parts that can go bad. The only cable is the main power supply.
The new LED emergency lighting is becoming increasingly popular with emergency agencies like police departments, ambulance services, and fire departments for many reasons. Besides being efficient in energy use, they have fast on/off transition time, thus facilitating attention-getting pulses. The diodes are rated for 100,000 hours of use, which translates to less downtime for emergency vehicles. Additionally, LED emergency lighting bars can be made very thin, thus producing minimal wind resistance and drag for emergency vehicles when they are moving fast.
LED emergency lighting lends itself well for use inside a vehicle also. They can usually be placed on the dashboard, visor area, or the rear deck. A large variety can be acquired, ranging from flat LED panels that are used under the sun visors, to strobe light that are mounted on the rear deck. Options of permanently mounting the lights or just plugging them into the car’s cigarette lighter are available. When permanently mounted lights are not used, the police car resembles a civilian car, thus making it harder to identify it as a police car.
Modern emergency lighting is now installed in almost all commercial and residential buildings. Usually, the lights are made up of incandescent bulbs or clusters of high-intensity LEDs. Most of these light sources can be directed to where maximum light is required, like towards fire exits. These systems operate using fairly low voltage, normally from 12 to 24 volts. This helps to reduce the battery size and cuts down on the load placed on the circuit to which the light is wired. Back-up batteries are usually made of lead-calcium and can last for as long as ten years or more on a continuous charge. Such lights can last for ninety minutes on the back-up battery power during a power outage.
Emergency lighting systems have come a long way since their inception. They are cheaper, smaller, and more efficient, while delivering greater brightness. Due to their versatility, they have a greater range of applications.