History of Street Lighting
It was introduced to the US by inventor Benjamin Franklin, who was the postmaster of Philadelphia, Pennsylvania. For this reason, many regard Philadelphia as the birthplace of street lighting in the US.
The colonial-era streetlights were lit by candles placed inside a glass vessel, which kept the candle from being blown out by wind. Franklin’s design was four-sided, with four separate panes of glass, so that if one pane of glass was broken, the lamp did not need to be entirely replaced, and might not even blow out.
After the invention of gas lighting by William Murdoch in 1792, cities in Britain began to light their streets using gas. The United States followed suit shortly afterwards with the introduction of gas lighting to Pelham Street in Newport, Rhode Island in 1803. Throughout the 19th century, the use of gas lighting increased. Some locations in the US still use gas lights.
After Thomas Edison pioneered electric use, light bulbs were developed for the streetlights as well. The first city to use electric street lights was Wabash, Indiana. Charles F. Brush of Cleveland, Ohio wanted to publicly test his new invention the “Brush Light” and needed a city to do so. The City Council of Wabash agreed to testing the lights and on March 31, 1880, Wabash became the “First Electrically Lighted City in the World” as a flood of light engulfed the town from four Brush Lights mounted atop the courthouse. One of the original Brush Lights is on display at the Wabash County Courthouse. By the beginning of the 20th century, the number of fire-based streetlights was dwindling as developers were searching for safer and more effective ways to illuminate their streets. Fluorescent and incandescent lights became popular during the 1930s and 1940s, when automobile travel began to flourish. A street with lights was referred to as a white way during the early 20th century. Part of New York City’s Broadway was nicknamed the Great White Way due to the massive number of electric lights used on theater marquees lining the street.
The two main competitors in the street lighting industry were General Electric and Westinghouse. During the 1950s, GE lit roadways with its Form 109 and, later, the popular Form 400. Westinghouse answered with the OV-20 model.
In 1957, a new breed of streetlight fixture was introduced; the “cobraheads”. If viewed from beneath they resembled a cobra’s flared neck. Westinghouse dubbed its cobraheads the Silverliners, which remained in production over the next 25 years. The OV-25 remains a popular streetlight fixture.
GE later introduced its own cobrahead, called the M400. The original M400 is noted for its pointed front end that protrudes over its bowl-shaped diffuser (also called a refractor). The M400 was the OV-25’s main rival. They carried 250–400 watts bulbs and were common on Interstate highways and city boulevards. GE made the M250 which was exactly same design as the M400 but using plastic refractor made for 250 watts. The M250 production ended in 1960 replacing with a M250R.
In 1964, Westinghouse produced an updated version of the OV-25, with a more rounded look. Only the diffuser was left unchanged.
In 1967, GE updated its M400 and M250 with its PowrDoor design. Gone was the protruding front end, and the new M400A and M250A were also more streamlined (although the original M400 and M250R continued to be produced until 1970). In 1970, a split-door M400 was introduced that shared the M400A’s bodyshell but had a nonvented door held in place with a spring latch, while the M400A’s vented door was held in place with a bail latch.
GE and Westinghouse also developed smaller fixtures. A miniature version of the M400 was made for suburban residential streets and alleys. That fixture was called the M250R which replaced the M250 which looked exactly like the M400 but with plastic lens and rated for 250 watts. In the same vein, Westinghouse offered three smaller Silverliners. The OV-12 (whose look resembles a miniature OV-50) came out in 1960, and it became the companion model to the Canadian-market OV-14B, which had been introduced in 1957. The OV-14B looks like a smaller version of the 1957-edition OV-25. Both the OV-12 and OV-14B were replaced by the OV-15 in 1965. These smaller fixtures carried 100–250-watts light bulbs.
The second-generation M400 and M250 were the first fixtures to sport the new high pressure sodium (HPS) lights that came out in 1966. The existing Silverliners could not handle these new lights, so Westinghouse developed a new OV-25, as well as a new OV-15. Both of these new Silverliners (also known as TuDors, and seen as Westinghouse’s answer to GE’s popular PowrDoor series) now had a flat bottom, and weren’t nearly as popular as the originals. However, by 1975, all Silverliners, including the single-door OV-15 and OV-25, were available as HPS units.
More new manufacturers entered the street lighting industry. ITT (also known as American Electric, or ITT/American Electric) developed two new fixtures, the Model 13 and Model 25. The Model 25 was later the basis for a larger lookalike, the Model 327. All three fixtures had a boxy look that usually sported grinning diffusers, a nod to the OV-15s and M250s. (Of the three fixtures, only the Model 327 is still in production.)
The Model 327, along with GE’s M1000 and Westinghouse’s OV-50, sported 700–1000 watts lights (see table).
Earlier versions of the M1000 and OV-50 (and, in very rare instances, the Model 327) are noted for having fins on top of the fixture. As newer ones were made, the fins were eliminated.
Some well-known light fixtures came from the Line Material Company. In the 1960s, during the height of the mercury lights’ popularity, Line Material produced the Unistyle 400 and the smaller Unistyle 175. Both of these fixtures combined various characteristics of the Silverliners and GE M-series fixtures. When the sodium era began around 1970, the company (by then, renamed McGraw-Edison) produced the boxy, rectilinear, more simplified Unidoor 400 (for metropolitan expressways and city boulevards) and Unidoor 175 (for smaller residential streets and alleys).
In 1982, the entire Silverliner line was discontinued, when Cooper Lighting bought Westinghouse’s street lighting division. Today, Cooper still makes the OV-50, now called the OVL. It also continues to manufacture the OV-15 and OV-25 models for sale in Canada.
GE and Cooper continued to take street lighting to new heights. GE was a pioneer in the full-cutoff arena, when it created a spinoff of the popular M400 and the rarer M250 in 1975. This fixture is noted for its pointed front end and lack of a diffuser. In addition, high-mast assemblies were developed for the light towers that were springing up along Interstate highways.
In 1988, ITT/American Electric also created spinoffs of its Model 13 and 25. These new fixtures, called the 113 and 125, had a more-rounded look than their respective predecessors. They have become the most popular fixtures not manufactured by GE or Westinghouse. While the Model 125 continues production today, the Model 113 was replaced by the American Electric Model 115 in 2003. In 1992, ITT sold American Electric to Thomas & Betts. In 2001, Thomas & Betts sold the street lighting division to Acuity Brands, where it was then spun off as American Electric Lighting.
In the mid-1980s, GE revamped its entire lineup. One, called the M400R2, had a flat bottom reminiscent of the third-generation Silverliners; the other, now called the M400A2, retained the original 1967 design but no longer had the vented door that the previous model did. Also, the M250R2 featured a slightly flatter profile than the M250R it replaced, and the M250A2 now took on the boxy profile that was previously used by the M150. In 1997, the M400 underwent a total redesign, borrowing its styling from the Thomas & Betts Model 125. In 2008, GE resumed production of the M400A2 and M400R2, which were sold concurrently with the 1997-edition M400 and M400A models until 2016.
In addition to the 1997 M400s and M400As, there have been many instances of manufacturers copying off another maker’s luminaires to create their own: For example, the Hubbell RLG400 has a look that closely resembles the Thomas & Betts Model 25, and ARK Lighting has two distinct fixtures that reuse the designs of the M250As and M250A2s (with the first example made to use 400 watts lamps, which the actual M250 series has never been equipped to handle).
More recently, teardrop lamps (both existing and reproductions) have been used in favor of cobraheads in both urban and suburban areas. They are usually complemented with bishop’s crook poles and more elaborate architectural elements. King Luminaire (a division of the StressCrete Group) manufactures these.
In addition to the existing manufacturers, newcomers such as Leotek have begun to make LED cobrahead luminaires to replace those that have used MV or HPS lamps.
Electric Light Generation Methods
Open Arc lamps were used in the late 19th & early 20th century by many large cities for street lighting. Their bright light required that the early arc lamps be placed on rather high (60 to 150-foot) towers; as such, they might be considered the predecessor to today’s high-mast lighting systems seen along major highways. They were also widely used in film and stage. Arc lamps use high current between two electrodes (typically carbon rods) and require substantial maintenance. Arc lights have mainly been used where high lumen light was needed such as lighthouses. Today very few open arc lights remain in operation, primarily in a few lighthouses and some industrial uses. The only remaining examples of original street lighting use are the moonlight tower of Austin, Texas.
A xenon lamp is a high pressure sealed arc lamp, and is in common usage today where extreme brightness in a relatively small space is required, typically in motion picture projectors in theaters, and stage and motion picture lighting. They are also found in car headlamps. The sealed arc lamps do not suffer from the inefficiency and high maintenance problems of the original open arc lamps, but they are not well suited for most street lighting use.
Incandescent lights using a tungsten filament were the first low power electric lights in cities worldwide and introduced some 20 years after open arc lamps[when?]. Some can still be found in streetlight service. Others have been installed in popular downtown areas of major cities to have a nostalgia effect. Incandescent light has excellent Color rendering index rated at 100. Color temperature is generally around 2000–3200 K depending on the type of lamp and replaced the higher maintenance arc lamps.
An incandescent light bulb is less efficient when compared to High-intensity discharge lamp and gas discharge lighting such as Neon light and are being replaced by more efficient CFL light bulbs or converted to MV or HPS. Tungsten-halogen incandescent lights which are brighter and more efficient and are very commonly used in theatrical and motion picture lighting and better color temperature characteristics are little used in street lighting due to their relatively short lifespan.
Standard incandescent lamps are very commonly used in traffic signals, although they are increasingly replaced by LEDs.
The fluorescent lamp first became common in the late 1930s. These lamps are a form of discharge lamp where a small current causes a gas in the tube to glow. The typical glow is strong in ultraviolet but weak in visible light. The glass envelope is coated in a mixture of phosphors that are excited by the ultraviolet light and emit visible light. Fluorescent lamps are much more efficient than incandescent lamps, and for a short time became popular in street lighting both because of the efficiency and the novelty value. Fluorescent lamps for street lighting were first introduced to the public for commercial uses at the 1939 World’s Fair.
The major problems with standard fluorescent lamps for street lighting is that they are large, and produce a diffused non-directional light. They are also rather fragile. Therefore, the fixtures needed to be large, and could not be mounted more than 20–30 feet above the pavement if they were to produce an acceptable light level.
Fluorescent lamps quickly fell out of favor for main street lighting, but remained popular for parking lot and outside building illumination for roadside establishments.
In 1948, the first regular production mercury vapor (MV) streetlight assembly was developed. It was deemed a major improvement over the incandescent light bulb, and shone much brighter than incandescent or fluorescent lights. Initially people disliked them because their bluish-green light made people look like they had the blood drained from them. Other disadvantages are that a significant portion of their light output is ultraviolet, and they “depreciate”; that is, they get steadily dimmer and dimmer with age while using the same amount of energy, and in a few rare instances, they also cycle at the end of their life cycles. Even rarer is they can burn out, especially when the light is being burned while dim (usually at the end of the life cycle). Mercury lamps developed in the mid-1960s were coated with a special material made of phosphors inside the bulb to help correct the lack of orange/red light from mercury vapor lamps (increasing the color rendering index(CRI)). The UV light excites the phosphor, producing a more “white” light. These are known as “color corrected” lamps. Most go by the deluxe (DX) designation on the lamp and have a white appearance to the bulb. Mercury Vapor Bulbs come in either clear or coated with powers of 50, 75, 100, 175, 250, 400, 700 or 1,000 Watts. The Mercury Vapor lamp is considered obsolete by today’s standards and many places are taking them out of service.
As of 2008, the sale of new mercury vapor streetlights and ballasts was banned in the US by the Energy Policy Act of 2005, although the sale of new bulbs for existing fixtures do continue, but the bulbs were also banned in 2015 in Europe. Mercury vapor fixtures can be operated with metal halide lamp (MH) ballasts, and are likely to be rewired with these ballasts in coming years. In response to the ban, some older MV streetlights will most likely be modified to use either high pressure sodium or metal halide lamps in the near future, because they are known to last longer than newer luminaires. In some areas where the MV lights are either failing or being replaced, they are being replaced by either HPS, LED, or Induction fixtures of similar lumen output, but also lower wattages and power consumption as well.
High Pressure Sodium
Around 1970, a new streetlight was invented: The high pressure sodium (HPS) light. They became common in the late 1980s. It was initially disliked by most residents because of its orange glow, but the sodium vapor streetlight has since become the dominant type on American roadways and most people have become accustomed to the orange/yellow glow. It is by far the most efficient light source available. Color-corrected sodium vapor lamps exist but are expensive. These “color corrected” HPS lamps have lower life and are less efficient.
There are two types of sodium vapor streetlights: high-pressure (HPS) and low-pressure (LPS). Of the two, HPS is the more-commonly used type, and it is found in many new streetlight fixtures. Sometimes, older (pre-1970) fixtures may be retrofitted to use HPS lights as well. Virtually all fixtures that are converted to HPS have previously been lit with mercury vapor. Examples of retrofitted fixtures for HPS use include the GE Form 400, first generation GE M400 and M250 and the second-generation Westinghouse OV-15 and OV-25 Silverliner (although later versions of this model were available from the factory as HPS units) as well as the Line Materials Unistyle 400 and 175/250.
LPS lights are even more efficient than HPS, but produce only a single wavelength of yellow light, resulting in a CRI of zero, meaning colors cannot be differentiated. LPS lamp tubes are also significantly longer with a less intense light output than HPS tubes, so they are suited for low mounting height applications, such as under bridge decks and inside tunnels, where the limited light control is less of a liability and the glare of an intense HPS lamp could be objectionable. Many LPS lights are also being changed out to HPS using FCO fixtures, or going to LED.
HPS lamps have slightly different electrical requirements than do the older MV lamps. Both HPS and MV lamps require a transformer or ballast to change the voltage and regulate the current, however, HPS lamps also require an electrical “starter” circuit—much like older fluorescent lamps in residential use. MV lamps do not require a separate “starter” circuit because they have a special starter element within the bulb used for striking the arc. MV lamps slowly dim over time, and a 20-year-old lamp may emit a very pleasing, but useless, soft green glow, rather than the powerful blue-white light of a new MV lamp. The yellow-spectrum HPS lamps also slowly dim over time but are known for “cycling,” where the lamp cycles on and off when it has reached the end of its life cycle. When cycling, the arc within the lamp extinguishes and the lamp must cool down before the starter circuit initializes a new arc. This has been the most recognized downfall of HPS. Some HPS lamps start to burn a pinkish/reddish color at the end of their life (usually when already cycling), or start to burn a pinkish/white color and go dim, or also burn out at the end of their life cycle whether they cycle or not. HPS fixtures can contain a special photocell or ballast that can sense a cycling lamp and shut off the fixture to prevent damage to the ignitor and ballast.
HPS lamps generally have the same rated lifespan as MV lamps, and they give increased light and efficiency at lower wattages. Usually, when an MV light is replaced, it is replaced with a HPS light of a lower wattage, for example, a 175 watts MV fixture will get replaced with a 100 or 150 watts HPS fixture as that will meet or exceed the lumen output of the 175 watts MV fixture. At end of life MV lamps just become dimmer and sometimes color shift towards the green end of the spectrum but continue to consume the same amount of electricity. HPS lamps begin to suffer end-of-life cycling before the amount of useful light becomes visibly diminished, or just burn out. HPS lights come in wattages of 35, 50, 70, 100, 150, 200, 250, 310, 400, 600, 750, and 1,000 watts’ sizes, while LPS lights come in wattages of 18, 35, 55, 90, 135, and 180 watts’ sizes
In recent years, metal halide lamp (MH) streetlights have illuminated roadways and parking lots. Metal halide has long been popular in business installations and can be found in warehouses, schools, hospitals and office buildings. Unlike the old mercury lights, metal halide casts a true white light. It is not nearly as popular as its sodium counterparts, as it is newer and less efficient than sodium.
Metal halide lights have also been used for retrofitting. Virtually all fixtures that are converted to metal halide have previously been lit with high-pressure sodium (HPS). Examples of retrofitted fixtures for metal halide use include the Thomas & Betts Model 25 and Model 327, as well as full-cutoff versions of GE’s M400. MH lamps suffer color shift as they age though this has been improving. Actual life expectancy is about 10,000 to 12,000 hours on average. There has also been a noted issue with the lamps “exploding/shattering” during a failure. Metal Halide light bulbs also tend to dim and/or flicker at the end of their life cycles, and on occasion, cycle. Sometimes, they emit a pinkish glow at or near the end of their life cycle which in this case, the bulb just burns out. High cost and low life hours has kept them from becoming popular municipal lighting sources even though they have a much improved CRI around 85. Therefore, the use of metal halide is limited mainly to city and high end street lighting. They are available in clear or coated bulbs. Probe start MH lights (which are less efficient and are also soon to be banned, unlike Mercury Vapor lamps) come in wattages of 50, 70, 100, 175, 250, 400, and 1000 watts’ sizes, while pulse start MH lights come in sizes of 50, 70, 100, 150, 200, 250, 320, 350, 400, 450, 750, and 1,000 watts’ sizes. The wattages of pulse start metal halide lamps are similar to HPS lamp wattages.
Ceramic Discharge Metal Halide Lamp
Ceramic discharge metal halide lamps promised to be the next step in street lighting, replacing old mercury vapor and high pressure sodium lamps, especially where a clearer white with better CRI (78–96) and light color retention was desired. CDM lamps give five times more light than comparable tungsten incandescent light bulbs (80–117 lm/W). However, continuing refinements in LED technology have now surpassed most other lighting types.
An induction lamp features extremely long lamp life (100,000 hours), energy efficiency, high color rendering index, and a color temperature close to incandescent lights. The life of induction (also known as electrodeless fluorescent) lamps is negatively affected by heat, particularly as the temperature exceeds 35 degrees Celsius (95 degrees Fahrenheit). Since temperatures in this range commonly occur during early night hours in the summer in much of the US, induction lamp applications have not extended beyond test and demonstration projects for street lighting. The larger size of the induction lamps also inhibits the effective control of the light they emit, limiting their use to lower mounting applications. [according to whom?] In 2009, PSEG in New Jersey began using induction lighting from US Lighting Tech, Inc. (Irvine, CA) to replace very old and even some pre-2008 mercury vapor lights, and have had success in their reliability and output of the fixtures. Unfortunately, some failed induction lights were spot replaced with the HPS lights that were being removed to begin with and many new installs, PSEG is still using HPS. An updated design of the induction lights is now being used and these seem more reliable and brighter than the original design. Beginning in September 2011 the City of San Diego, CA will replace some 35,000 street lights with induction lamps costing $16,000,000.00. In Mexico, the city of Linares and Acapulco also have begun the replacement of 6,500 and 42,000 street lights with induction lamps from Amko SOLARA Lighting (Taipei, Taiwan), selected for their smart controls, since October 2011. A portion of these street lights from Amko will feature smart grid compatibility to allow the lights to be remotely monitored and controlled via the Internet.
Compact Fluorescent Lamp
Compact fluorescent lamps (CFL) have been used more frequently as time has improved the quality of these lamps. These lamps have been used on municipal walkways and street lighting though they are still rare at this time. Improvements in reliability still need to be made. Some issues with them are limited lumen output, high heat buildup in the self-contained ballast, low life/burnout due to frequent cycling (on/off) of the lamp, and the problem where most fluorescent sources become dimmer in cold weather (or fail to start at all). CFL efficiency is high and CRI is excellent around 85. CFL produces a color temperature around 3000 K with its light being “soft white” around that color temperature. Higher color temperatures are available.
Light Emitting Diodes
Light emitting diodes (LED) have virtually replaced both incandescent lamps and the occasional fluorescent lamp in traffic signal and crossing sign usage. They are rapidly developing in light output, color rendering, efficiency, and reliability. The cost of LED lighting is still high compared to an incandescent or arc-discharge lamp used for the same purpose, but the cost is decreasing rapidly. Even with the high per-unit cost, the increase in efficiency and increased lifespan make them very attractive for street lighting use. The reduced cost of electricity and maintenance in some cases can offset the increased cost of the lamp.
LEDs are increasingly finding widespread usage in general street, sidewalk, or parking lot illumination as technology improvements bring their brightness and cost into competition with HPS, MH, or CFL lighting. For example, the city of Ann Arbor, Michigan, implemented LEDs in street lighting applications in March 2006 and have since expanded their use. In addition Chapel Hill, North Carolina, entered a 12-month test program and partnership with Duke Energy on March 25, 2009, to evaluate the effectiveness of replacing existing HPS lighting with the more efficient LED street lighting within its vibrant downtown. In late 2008, Anchorage Alaska installed over 4,000 LED streetlights as part of a plan to convert the community’s 16,000 roadway lights to efficient white light. In mid-2009, the City of Los Angeles announced a 5-year project with the Clinton Climate Initiative to replace all 140,000 of the city’s existing streetlights with LED fixtures. In mid-2010, Seattle City Light began installing LED streetlights in a residential neighborhood as part of a plan to install 40,000 LED streetlights over the next 5 years. Also, Atlantic City Electric in Southern NJ is also testing out LED streetlights made by 2 different manufacturers in 4 communities to evaluate if LED lights are worth using over HPS. As of late 2015, Atlantic City Electric has decided to go ahead and replace all utility owned or leased MV and HPS cobra head and floodlights with LED lighting, if the municipality is interested (which many are). The town of Stratford, NJ was the first town in their service territory to receive the new LED lights, with many more to follow. The parking lot at Camden County College in Blackwood, NJ is now using LED post lights that replaced the previous HPS flood and shoebox lights. The Cities of Philadelphia and New York have also begun testing LED streetlights and Philadelphia is now in the process of changing existing HPS lamppost lights from HPS to LED and all new installs are LED. Philadelphia is also conducting a study to see if it will be feasible to replace all city owned street lights with LED by 2018 (about 60,000 lights) and many areas of the city already have them; other major cities, such as Baltimore and Charlotte, have already begun to replace their HPS lights with new LEDs in different sizes. The town of Abington, PA has installed LED streetlights on their main and secondary streets to replace MV fixtures. In spring of 2011, the municipally-owned energy provider for San Antonio, Texas, CPS Energy, entered into contract with GreenStar LED (of Boerne, Texas) for an order of over 25,000 LED street light fixtures. LED street light have been introduced also in smaller cities and communities, for example, in Brisbane, CA.
As with other semiconductors, heat buildup in an LED dramatically reduces its life. The temperature at which this reduction in life occurs is often very near summer evening ambient temperatures. Many of the heat-removal technologies used for other semiconductor applications, such as air conditioning systems, fans, or thermal-transfer fluids, are impractical, maintenance-intensive, or cost-prohibitive for street lighting. Airborne dust from industrial and agricultural activities can impair the functioning of finned heat sinks. Achieving good maintenance-free thermal management in an often hostile environment while keeping product cost competitive is the largest hurdle to the widespread adoption of LED street lights.
The non-cutoff fixtures usually include the globe-shaped lamps that are mounted atop lampposts. These lamps distribute light in all directions. A major problem is created by the light pollution and glare, as they shoot their light upwards into trees and towards the sky rather than towards the ground. Non-cutoff fixtures are rarely found on roadways because they tend to blind the driver.
This is the most popular street lighting optic. The semi cutoff fixtures usually refer to the cobraheads, but they can also apply to some lamppost-mounted fixtures that do not emit their light upwards. Most of the light can be emitted below 90 degrees, but as much as 5% of the light can also be emitted above 90 degrees. These fixtures do a good job of spreading the light towards the ground but some uplight is possible, though not as serious as non-cutoff fixtures. Semi cutoff fixtures are often mounted on tall poles. Examples of semi cutoff optics include the bowl-shaped diffuser on GE’s M400s made prior to 1997, and the prismatic one shared by the Westinghouse OV-25, Crouse-Hinds L250 and OVM, and Cooper OVD. These fixtures are commonly seen with both mercury vapor and HPS lamps (and sometimes metal halide as well).
These optics give more light control than semi cutoffs. Less than 2.5% of the light can leave the fixture above 90 degrees. Cutoff fixtures have gained popularity in recent years, as they are available from manufacturers like GE and American Electric. The cutoff lights have a wider spread of light than full-cutoffs, and they generate less glare than semi cutoffs. The cutoff lenses consist of a shallow curved glass (also called a sag lens) that is visible just below the lighting area on the fixture. As with the semi cutoffs, these fixtures are very commonly seen with both mercury vapor and HPS lamps (and occasionally with metal halide as well).
These lights do not allow any of the light to escape the fixture above 90 degrees. Full-cutoffs distribute their light in a defined pattern, potentially providing more light on the ground at lower power consumption. In recent years, cutoff-type lights have gained popularity. Although full-cutoff fixtures generally use HPS lamps, some metal halide and even a few mercury vapor ones are known to exist, and recent LED fixtures use this optic as well.
Semi cutoff refractor compatibilities
Small fixtures (175 watts and under)
- Round design: This refractor is shaped like a half-circle, and is usually found on fixtures operating at 150 watts and lower. Examples of round refractors include the ones used by the Thomas & Betts/American Electric Models 13/113/115 and General Electric M250.
- Flat design: This refractor uses a prismatic design, and has a flat bottom. It is most commonly found on fixtures operating between 100 and 250 watts. Examples of flat refractors include the ones used by the Thomas & Betts/American Electric Models 13/113/115, Westinghouse OV-15, Crouse-Hinds L150 and OVS and Cooper OVX and OVZ.
- Square design: This refractor is shaped like a square, but some newer incarnations may also have a slightly rounded bottom. Examples of square refractors include the ones used by the General Electric M250, Line-Materials Unistyle 175, McGraw-Edison Unidoor 175/250, Crouse-Hinds L150 and OVS and Cooper OVX and OVZ.
- All three refractor designs are compatible with any small fixture, except the Westinghouse OV-10, OV-12 and OV-14B (which share the same unique refractor design).
Medium fixtures (200–400 watts)
- Round design: This refractor is shaped like a half-circle. Usually found on General Electric M400s made prior to 1997 (and select models from 2008 onward), they are also used by the remote-ballasted GE Form 400 and Revere 400-watts models. Line-Materials/McGraw-Edison used a slightly different round refractor design for the Unistyle 400 and Unidoor 400.
- Prismatic designs: There are many different versions of the prismatic refractor design. A larger version of the flat design is used on the Westinghouse OV-25, Crouse-Hinds L250 and OVM and Cooper OVD. Another popular design features rounded-off corners, and is compatible with Thomas & Betts/American Electric Models 25, 125 and 325, as well as the 1997 and later editions of the General Electric M400.
- The Unistyle 400/Unidoor 400 refractor is also interchangeable with the Model 25, and vice versa.
Large fixtures (up to 1000 watts)
- The Westinghouse OV-50/Cooper OVL refractor is used by the remote-ballasted Westinghouse OV-35 and Revere 1000-watts models, and although there has been very little-known evidence of this, the OV-50/OVL refractor is also interchangeable with the Thomas & Betts/American Electric Model 327, and vice versa.
- The round refractor design as seen on the General Electric M1000 can also be used with the remote-ballasted GE Form 402.
Fixture Type Identification
Many streetlights are marked with a NEMA wattage label to aid workers in identifying them.
The system is as follows: The color of the sticker indicates the type of light, the number is one tenth of the power in watts. The higher the number, the brighter the light.
There are three exceptions to this rule:
- A “17” sticker adds a five to the power rating, and therefore, the light is rated at 175 watts.
- If a sticker reads “X1,” it describes a 1000-watts light.
- If a sticker reads “3,” it describes a 35-watts light.
- Also MH stands for Probe Start Metal Halide, while PSMH stands for Pulse Start Metal halide.
- Sticker colors:
- Purple: Incandescent
- Blue: Mercury vapor
- White: Light-emitting diode or older HPS
- Soft White or Colored: Compact fluorescent lamp
- Red: Metal halide (Probe start)
- Half Red/Half White: Pulse Start Metal Halide (PSMH) and some CMH
- Yellow: Older HPS, LPS, and some induction and some CMH
- Orange: new sticker color, now used for HPS
Colors vary for new LED street lights such as black for Philips Hadco RX1 and RX2 or Green for BetaLED luminaires. The Induction fixtures usually contain a green and white sticker. Some CMH lights also use a yellow sticker as well as red/white. Some LED stickers have the full wattage on them (Example: it will read 50 LED, which identifies the fixture as a 50 watts LED fixture)
Frequently seen power ratings:
- “3” sticker – 35 watts (HPS/LPS)
- “4” sticker – 40 watts (Induction)
- “5” sticker – 50/55 watts (MV/HPS/LPS/PSMH/LED)
- “7” sticker – 70 watts (HPS/PSMH/MH/LED/Induction)
- “8” sticker – 80 watts (Induction)
- “9” sticker – 90 watts (LPS)
- “10” sticker – 100 watts (MV/MH/PSMH/HPS/Induction/LED)
- “11” sticker – 110 watts (LED)
- “13” sticker – 135 watts (LPS)
- “15” sticker – 150 watts (HPS/PSMH/Induction/LED)
- “17” sticker – 175/179 watts (MH/MV/LED)
- “18” sticker – 180/189 watts (LPS/LED)
- “20” sticker – 200 watts (HPS/PSMH/LED)
- “25” sticker – 250 watts (MV/PSMH/HPS/Induction/LED)
- “27” sticker – 270/274 watts (LED) or 100 watts (HPS)
- “28” sticker – 285 watts (LED)
- “31” sticker – 310 watts (HPS)
- “32” sticker – 320 watts (PSMH)
- “35” sticker – 350 watts (PSMH)
- “37” sticker – 37 watts (LED) – New: For BetaLED’s luminaires in Boston, MA
- “39” sticker – 39 watts (LED) – New: For BetaLED’s luminaires in Boston, MA
- “40” sticker – 400 watts (MV/PSMH/MH/HPS)
- “45” sticker – 450 watts (PSMH)
- “60” sticker – 600 watts (HPS)
- “70” sticker – 700 watts (MV)
- “70” sticker – 70 watts (LED)
- “75” sticker – 750 watts (HPS/MH/PSMH)
- “X1” sticker – 1000 watts (MV/HPS/MH/PSMH)