Driving Lights - What Are They and How do You Use Them?
"Are you allowed to drive with both headlights and driving lights on at the same time?" asks a reader. The question was prompted by this person's complaint of being blinded by the lights of many of today's vehicles. These vehicles display two headlights and two of what many people assume to be driving lights.
What is a Driving Light?
According to vehicle lighting expert Dan Stern, "driving lamp" or "driving light" is a widely misunderstood term. People use it to mistakenly refer to all kinds of different lights, including fog lights. It sounds like a kind of lamp you can use whenever you're driving, but that's not the case.
In fact, driving lamps are auxiliary high beams. They're designed to add to the reach of the high beam headlights. Unlike low beams, their beams are not designed to control glare at all, and so driving lamps are effective, safe, and legal only for use together with the vehicle's main high beam headlamps on dark, empty roads (or off road).
Never with low beams, never by themselves, never in traffic, never in bad weather, and never within glare distance of other vehicles ahead, in either direction.
Driving Lamp Identification
Driving lights are identified by the markings SAE-Y on North American lamps or the letters HR above the circle containing the E on European lamps. You are allowed to install two of them that must display white light.
Mounting and Aiming
Driving lights must be mounted between 40 cm and 1.06 m from the ground level and aimed so that the high intensity portion of the beam is, at a distance of 8 m from the lamp, at least 12 cm below the height of the lamp and, at a distance of 25 m from the lamp, not higher than 1.06 m from the road surface. The lateral aim is +/- 150 mm at a distance of 7.62 m from the lamp.
All measurements are made to the center of the lamp.
Wiring and Operation
In addition, these lamps must be wired so that they only come on when the high beam headlights are illuminated. This is usually accomplished through the use of a relay that is triggered when the headlights are switched to high beam. This would mean that a driver would shut off driving lights no closer than 150 m to another vehicle being approached or overtaken.
Driving lamp glare elimination is the ultimate responsibility of the driver of the vehicle using them. Keeping them clean and properly adjusted will solve many complaints and dimming them responsibly will solve most others. Enforcement is the responsibility of the police and the Superintendent of Motor Vehicles as the use of this type of lamp is not regulated by the federal government through Transport Canada.