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Carbon Arc Lights 101

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Before the introduction of incandescent bulbs and LEDs, carbon arc lamps ruled the commercial lighting sector. Previously, the outdated luminaries were used to light up streets, support filming projects and illuminate local landmarks for travelers. The fixtures helped kick start the electric lighting era by encouraging the development of commercial units, including early motion picture Kliegl lights, the iconic Jablochkoff Candle and mercury arc lamps (not to be confused with mercury vapor lamps).

History and Overview

Carbon arc lights (not incandescent lamps) were the first electric light sources to hit mainstream use. In 1802, Sir Humphry Davy pioneered this type of technology through the generation of an arc based on the connection of two large pieces of charcoal attached to a powerful supply of electricity (2,000 voltaic cells). He did not capitalize on the production of carbon arc lights during the discovery. Instead, other scientists helped develop the technology using his initial findings. Davy also made notable contributions to safety features found in today’s mining lights.

In 1834, William Edwards Staite from Britain picked up where Davy left off and started his own experiments with carbon arc lights. Two years later, the scientist was able to manipulate the light by regulating the movement of carbons inside the unit via clockwork mechanisms. He also applied for numerous patents, as he developed the foundational features of the luminary. As with most newly released electronics, the lamps were too costly to be used on a daily basis. Specifically, the batteries required during light output were extremely expensive. This was the main issue that was preventing the unit from reaching mainstream markets.

Enclosed and Flame Arc Lamps

Four decades after Staite’s contributions, adoption for arc-based lamps started to take off due to the introduction of cheaper batteries and reliable, steam-driven generators. Between 1880 and 1900, manufacturers released updated models with enclosed and flame arc features, which helped push adoption even further. In enclosed arc lamps, a glass tube inside the unit’s main casing surrounds the arc. This effectively decreased the use of carbons (by reducing airflow around the arc) during light output up to five times. As a result, maintenance for the luminaries was greatly reduced; however, the unique design required more power during light generation.

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To promote brightness, flame arc lamps with fiery salt components were introduced. The core mixture was composed of the following: magnesium, strontium, barium and calcium. In addition to increased light intensity, the compounds added to the light’s color profile. By 1910, carbon arc light installations reached its peak at 20,000 luminaries in populated British locations and cities. The introduction of the arc-based Jablochkoff Candle supported the manufacturing and use of the technology in massive quantities.

Light Generation and Output

Carbon arc lights go through a tedious process during light production. The unit is made up of two carbon electrodes with gaseous components in the center. During operation, the electrodes, which are suspended in the air, are touched together to ignite the arc. Afterwards, current is maintained during output to ensure consistent illumination. Because heat is not regulated closely in carbon arc lamps, the carbon rods are prone to burning.

This type of lamp came with several major disadvantages, which were eventually addressed in newer forms of lighting technologies. As mentioned earlier, maintenance of failing, expired or burned lamp parts became top priority for cities that installed carbon arc lights around parks and streets. Unenclosed models of the fixture were fire hazards and ignited many commercial establishments, such as theaters and industrial buildings. The lights also generated generous amounts of UV light (UVA, UVB and UVC bands), radio frequency interference and deadly carbon monoxide (CO). This put technicians and operators at serious risk, either causing blindness from persistent exposure to harmful UV rays, bodily damage from CO emissions or unforeseen ignitions due to lack of safety features.

On the positive side, arc lamps boasted intense lighting conditions, reaching as high as 2,000 – 4,000 candlepower. Because of this, reliable models of carbon arc lamps can be seen from distances as far as five miles away. By comparison, incandescent bulbs only support 16 candlepower.

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Commercial and Industrial Applications

These days, carbon arc luminaries are not widely used due to their inefficient and unsafe light generation mechanisms. Although it is important to consider that there are other forms of arc lighting available, such as fluorescent lamps, flash camera lighting, UV fixtures and theatrical lights. During peak usage in the 1800s, they were mostly applied in outdoor lighting systems. An 1881 report from Scientific American suggests that the fixtures supported the following industrial operations: steel manufacturing, rolling mills, mining and railroad services. In commercial settings, the lights could be found in docks, parks and streets.

Eventually, the downfall of carbon arc lamps helped usher in the era of incandescent lighting. Edison addressed the pitfalls of carbon arc lamps by introducing a new way of generating light via heating up a wire, instead of violent sparks. The scientist’s old notes revealed that he crafted a new way to divide the arc light into smaller components, so that people can view the light with minimal visual strain. Before incandescent lighting took off, carbon arc fixtures were still being used in lighthouses and stadiums. In London, the city depended on such luminaries for street lighting up to the 1950s.

Carbon arc lamps were prevalent in movie recording studios, and were known for their bright output capabilities. However, because they generated intense levels of UV light, some actors and individuals on the set wore sunglasses outside of filming to provide relief against eye soreness and inflammation.

Below is a shortlist of lighting products available from Larson Electronics:

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