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Lighting Term Glossary

Technical article from Anderson Marine


Auto Select is Peterson's trademark name for a selected group of imported automotive products. Unlike other imported products, Auto Select are designed, built and quality-inspected to PM's stringent standards.


Peterson's trademark name for snowplow and emergency lights.


The most important part of a lamp is the bulb.

Incandescent —there are two basic incandescent bulb styles most frequently used in general lighting products.

  • Bayonet Base —traditional, widely used metal-based bulb such as 1156, 1157 or 1895.
  • Wedge Base —non-indexed, bulb without a metal-based bulb such as 193, 3056, or 3157.
  • 15,000 Hour-Rated Bulbs —a bulb is rated by the number of hours it will burn under ideal laboratory conditions. Peterson uses 15,000 hour bulbs, whenever possible, to achieve maximum performance.

Halogen —commonly known for bright, intense light from a small package. In Halogen bulbs, Tungsten particles from the filament are continually redeposited back on the filament rather than the bulb's interior as is the case with incandescent bulbs. Halogens are available in H1 and H3 bulb and sealed beam configurations.

Xenon —a bulb type commonly used in emergency warning lights. Xenon refers to an additive in the gas sealed inside the headlights. It serves as a starter in order to accelerate the start up process of high-intensity discharge headlights.


There has always been some confusion between a fog and driving light beam pattern.

Fog Beam —provides a low, wide pattern to greatly increase short-range visibility. Ideal for added driving safety in rain, snow or fog.

Driving Beam —produces a long-range pencil-shaped light pattern. Greatly increases night time visibility at highway speeds.


In 1966, the U.S. Congress enacted the National Traffic and Motor Vehicle Safety Act. This authorized the Department of Transportation to establish uniform safety standards for new vehicles. These standards regulate such products as brakes, seat belts, steering wheels, gas tanks, etc. FMVSS 108 regulates head lamps, tail lamps, stop lamps, reflectors, marker lamps, turn signals, ID lamps. etc. Virtually all lighting-related products in our catalog exceed this regulation.


There are three basic types of warning lights:

1. Flashing —this functions just as the name describes...a bulb of some type flashes or blinks on and off to provide a visible warning signal.

2. Revolving —the revolving series is available in several variations:

  • 2-Beam —uses two sealed beams or light bulbs that rotate to produce a full, 360° warning.
  • 4-Beam —uses four sealed beams, an upgrade from the 2-beam unit.
  • Rotating Reflector —features a stationary light source with a revolving reflector to produce the 360° warning. This design is commonly used in light bars and compact units.

3. Strobe —simple way to understand strobes is to think of them as very bright, flashing lights.Obviously, there is much more to strobes than this...electronic components, specialized bulbs and/or tubes, etc. The light output from strobes is measured in joules, candela or watt seconds.

  • Quad Flash —this unit flashes one strobe light head 4 times (quad) and then flashes the other strobe light head 4 times.
  • Master and Slave Units —the master unit has a built-in control circuit, will operate independently by itself and can operate a slave unit. The slave unit has no built-in control circuit and requires the master unit to operate.
  • Joule —a strobe rating of the amount of power delivered per flash. Joule is the energy produced by the circuit for a single flash or single group of flashes.
  • Watt-Second —the amount of energy delivered per second.
  • Candela &mdashthe amount of light seen through a clear lens during one second.


The Peterson Piranha® LED lights are unsurpassed in optics, manufacturing technique and state-of-the-art electronic design. Some of the features of Peterson's LED series are:

  • 100,000-hour rated life
  • Vibration resistant
  • Low amp draw...use 1/10 of the electrical current needed to operate standard bulbs
    • Faster response time for added safety
    • Solid state—no filament to break
    • Maintenance free


In accordance to FMVSS 108, Peterson uses two thermal plastic resins...acrylic and polycarbonate:

  • Acrylic —the most widely used material for lenses. Features moderate heat and impact-resistance. Reasonably priced.
  • Polycarbonate —a premium material with higher impact and heat resistance than acrylic.


A method of of welding two similar plastic materials together by vibrating one part horizontally at a controlled rate against the other, producing heat and a hermetically-sealed bond.


Peterson's trademark name for our custom wire harness systems specifically designed for the heavy-duty trucking industry, and our electrical accessory program for the aftermarket.


Peterson offers a complete line of passenger car, light truck and van, and heavy duty mirrors and assemblies.

  • Convex —also known as "blind spot" mirrors. Features a fish-eye design permitting a wider view angle than a traditional mirror.
  • Elliptical —features a protruding, half-moon shape design that allows driver to view a 180° area with a mimimum of distortion.
  • Wedge Base Convex —an improved version of the traditional convex. Allows over 50° increase in viewing area with less distortion.


Nightwatcher® is Peterson's trademark name for the entire line of high quality fog, driving and off-road lights and accessories.


Photometry is the calculation and measurement of quantities of light, such as luminous intensity. This is usually measured in candela or candlepower.


Peterson's trademark name for our exclusive microprismatic, wide angle reflectors. 47,000 microprisms per square inch provide superior candlepower compared to conventional reflectors.


A submersible light allows water into the unit when submerged. The bulb and socket are protected by an air pocket formed by the "Belljar principle" which permits only a certain amount of water to enter, not allowing water to come in contact with the bulb.


Developed in the 1960's, Peterson's VIBAR® was the first real shock-mounted socket in the industry and eventually became the standard. This exclusive, resilient socket absorbs road shock and vibration for longer bulb life.

Original article from Anderson Marine

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