Flashing emergency vehicle lights are most commonly seen on police vehicles, ambulances, and fire engines. These vehicles, when they are moving in response to an emergency situation, have to be allowed to move faster than the other vehicles on the road. Flashing of emergency vehicle lights, together with sirens, ensures it.
However, emergency vehicle lighting is not the prerogative of just these departments. An emergency vehicle light can be purchased by any ordinary citizen and law does not ban his right to buy it. It is not illegal for private personnel to have an emergency vehicle light mounted on his vehicle but his right to operate it is controlled by laws.
Most countries allow volunteer firefighters, rescue workers, and emergency medical services personnel to use emergency vehicle lights on their vehicles, though the laws regarding it varies from country to country and from state to state. In the UK, private ambulances and fire brigades are allowed to sport emergency vehicle lights of the same type sported by public services.
In the United Kingdom, a doctor moving in response to an emergency situation is allowed to have a green emergency vehicle light on his car. The provision in New Zealand is similar where registered doctors, nurses, and other medical workers are allowed to have a green beacon on their vehicles.
Green lights are considered in many places as courtesy lights, which means that the vehicle sporting that emergency vehicle light is rather requesting right of way than demanding it. In some states of USA volunteers are allowed to use red emergency vehicle lights while in some other states they are allowed to use blue or green. In the latter instances the lights are seen as courtesy lights
In USA some states allow volunteer personnel to use emergency vehicle lights on their vehicles but restrict the use of sirens, while other states allow the use of both. Since the color of the emergency vehicle light that volunteer firefighters are allowed to use vary from state to state, they have to be very careful while crossing borders. A volunteer sporting a red emergency vehicle light might have to change it into blue or switch off his siren when he enters another state, or may become liable to punishment.
Detailed laws regulate the use of emergency vehicle lights by volunteers. For example, even where volunteers are allowed to use red lights, there could be several qualifying conditions on its use. Rules like the emergency vehicle light should not be part of the regular lights of the vehicle, should be mounted on the roof or the dashboard, should use a red lens and not a plain lens with a red bulb, should be free of inscriptions, and should be less than 8” in diameter, are some of the conditions that may qualify the use of emergency vehicle lights.
Larger emergency vehicle lights like light bars which are used by police or hospitals are by and large expensive and it may not be worthwhile for volunteers to invest on it. They will be able to manage emergency situations by having strobe kits in their cars, or using smaller dash, deck, or visor lights that can be easily detached and mounted on different parts of the vehicle. There is an emergency vehicle lighting mechanism known as ‘flasher system’ which when wired to the car will utilize some of the existing lights in the car to produce a flashing light when required.