We are constantly asked "Where should I start?" "What lights do I need?"... we found this guide to be the most helpful when determining your emergency lighting needs. This tutorial comes from ELightbars.org which is a forum of the best minds in the emergency vehicle equipment and lighting world. If you have suggestions, please let us know!
All emergency vehicles should have full 360-degree coverage. This is mandated by law many places. The simplest way to achieve this is by using a beacon or full size lightbar. However, a minibar will work just as well in most cases.
If you drive a tall vehicle, remember that the beacon can be hidden to vehicles close to you, and you may need two beacons diagonally mounted.The same problem applies to minibars and lightbars, so you might need to add some additional lighting.
If you replace the roof-mounted light with interior lights, remember that you still need adequate warning lights facing to the sides.
Also: consider the "viewing-angle" of the light you install: a vertically mounted TIR-style module will give a very narrow "field of view", where as a horizontally mounted linear-style module wil give a much wider "field of view".
When navigating through dense traffic, remember that only a small part of your vehicle may be visible to oncoming drivers.
One of the more dangerous situations when responding is navigating intersections, especially red lights or intersections where others have the right of way. If your vehicle is partially hidden by other vehicles, your lightbar or sidemounted warninglights may not be visible, and your siren is pointing forward. Hence, it is recommended to mount some form of outward-facing warninglights towards the front of the vehicle.
Avoid flashing or interfering with your turn signals as you ought to use them in communicating with oncoming traffic when driving, even on response (standard curriculum in emergency driving courses)!
Some lights will cover both width and front intersection warning, such as properly places HAWs in vehicle cornerlights or surface-mounted on side of bumper. A very minimal install could look like this: Nighttime low-power option If your vehicle is equipped with a lot of warning lights, it is highly recommended that some or all of these can be turned down during the darker hours, to avoid blinding other drivers.
The idea that blinded drivers will slow down is false!
Some simply carry on, either from stupidity or confusion, and will not be able to see officers in the best of reflective gear. Studies have also shown that drivers tend to skew towards where they are focused. Think of your car: it has driving lights and parking lights, and in driver-education you probably learned to turn off your driving-lights when parked, to allow for other drivers to see the contours of your vehicle and any people or other vehicles next to or behind it. The same applies to warning-lights. DO NOT BLIND OTHER DRIVERS!
Final Pro Tips:
Keep it slow and synced. Your car is not a disco or a Christmas Tree!
Keep to slower patterns and sync your lights to give clear and distinct flashes, meaning "on and off" periods.
Using split pattern will also decrease the power of each flash, since your never flashing all of the leds at once, only half at a time. This, combined with fast flash patterns, is what is often called "split-fail". This especially applies to vehicles with two colors, such as red and blue. If you mix these colors with fast and/or split patterns, people will only perceive you as a "purple blob". Reds and blues should be well separated, either by time (flashpattern) or by distance (placement on vehicle)!
Avoid flashback If you are using interior lightbars or decklights, keep them flush with the window to avoid flashback, meaning light reflected of the glass or via the dashboard. This WILL impair your vision when driving in the dark and is a completely unnecessary risk!
Finally, always check with local regulations and abide by them! If local regulations require your vehicle to meet a certain standard; comply with it!