Many people swear by headlights with HID bulbs, short for high intensity discharge. These types of lights can improve visibility because they emit a bright, blue-white light that approximates natural light. On the down side, they can blind other drivers with the glare they produce. Some states allow HID headlights, but California allows only headlamp bulbs that emit light that is white or yellow, which means that only low-intensity HID lights are legal.
TL;DR (Too Long; Didn't Read)
California permits only headlamp bulbs that emit white or yellow light. Since high-intensity HID bulb light is blue, these lights are not permitted on vehicles in the state. Cars sold with HID lights installed are permitted because the manufacturers make sure the lights are low intensity, but aftermarket HID kits usually provide high intensity blue light and are illegal.
What Are HID Lights?
HID is shorthand for high intensity discharge. This term describes how bulbs generate light when electricity is sent through an ionized gas. HID headlamps are not the only type of HID lights – neon lights generate light in the same way. These type of lights are useful when a particularly bright light is needed and are often used in street lighting as well as sports stadiums.
Generally, HID bulbs include two tungsten electrodes in a glass enclosure. The enclosure contains xenon gas and metal-halide salts. That explains why HID headlights are often called xenon lights. They can reduce the time an HID light bulb requires to warm up to maximum illumination.
A regular car system operates on a DC current circuit in the 12V to 14V range, but HID bulbs require a higher voltage AC circuit. They use a ballast that connects to the car’s control system to balance out the current. When you buy a car with an HID-bulb system installed, the ballast is already integrated into the cars electronics. Otherwise, you need to add a ballast to make the HID bulbs work.
Positive Aspects of HID Headlights
Drivers appreciate HID headlights because they produce a greater amount of light per unit of power than the standard tungsten-halogen car headlights. In fact, they use less than half of the energy of equivalent tungsten-halogen lights. That means you get a brighter light for less power, improving fuel consumption.
HID lights also last longer than halogen-type lights thanks to the fact that they don't have a filament. The lack of filament in an HID bulb makes them more durable, and HID bulbs have an expected lifespans of some 5,000 hours.
Finally, a variety of colors of light are available. The hue of the light in headlights is based on a temperature scale and rated in Kelvin units. Most halogen bulbs come in between 3,000K and 3,500K, which produces a yellowish light. HIDs can be almost any color, but the ones most frequently used in retrofit kits in vehicles produce 4,500K to 6,000K light. This is closer to natural daylight and a white-blue light.
Downsides to HID Headlights
A driver who wants better light from their headlights should be prepared to pay for it. Cars with HID headlights are more expensive than those with regular headlights, adding a few hundred dollars to the car price.
The replacement bulbs cost more than halogen replacement bulbs, too. HIDs can dim over time. That means that after a few years, the headlights of a car equipped with HID headlights may emit less light than when they were new. That may require more frequent replacement than the 5,000 hours advertised.
Finally, HID headlights are not legal in all states. In some areas, like California, they are legal only if the car is purchased with these headlights and they are low-intensity. Generally, aftermarket conversion kits are not allowed.
California Headlight Law: Light Color
California law does not mention HID headlights at all. This means that HID headlights are not explicitly outlawed under California law, but they are not explicitly permitted either. California Vehicle Code Section 25950 mandates that vehicle headlamps are clear and emit yellow or white light:
"Unless provided otherwise, the color of lamps and reflectors upon a vehicle shall be as follows: The emitted light from all lamps and the reflected light from all reflectors, visible from in front of a vehicle, shall be white or yellow..."
This statute means that headlights that emit a blue light are illegal in the state. Recall that HID lights can vary in color. HID bulbs come in a variety of colors ranging from yellows (3000K to 4300K) to whites (5000K to 6000K) to blues and purples (8000K and over). Lower intensity HID bulbs emit yellow or white light, and higher intensity HID light is blue. Any HID headlights emitting blue or purple light are in violation of the California statute.
California Headlight Law: Legality of Aftermarket Lights
If HID lights come pre-installed in a vehicle, the original equipment manufacturer (OEM) makes sure that they are a low-enough intensity not to produce blue light. That means that these HID lights are legal under California state law. If a driver buys a new vehicle that comes with HID lights, there should not be a problem. Likewise, if they buy a used vehicle that was sold with HID lights installed when new, it should be okay, too.
However, if a vehicle is lifted or raised aftermarket, that could make the HID lights more disruptive to drivers ahead of the car, shining directly into the back window. If the vehicle has been lifted to the extent that the HID headlights are making it difficult for the car ahead of you, a police officer may cite you. The state's Vehicle Code requires that these lights be no lower than 22 inches and no higher than 54 inches from the ground.
What about after-market HID conversion kits? Installing aftermarket HID headlights in a vehicle that came with halogen lights is illegal in California. That is because these kits come with very intense blue HID light, which is illegal in California.
Teo Spengler earned a J.D. from U.C. Berkeley's Boalt Hall. As an Assistant Attorney General in Juneau, she practiced before the Alaska Supreme Court and the U.S. Supreme Court before opening a plaintiff's personal injury practice in San Francisco. She holds both an M.A. and an M.F.A in creative writing and enjoys writing legal blogs and articles. Her work has appeared in numerous online publications including USA Today, Legal Zoom, eHow Business, Livestrong, SF Gate, Go Banking Rates, Arizona Central, Houston Chronicle, Navy Federal Credit Union, Pearson, Quicken.com, TurboTax.com, and numerous attorney websites. Spengler splits her time between the French Basque Country and Northern California.