How Tall Is A Street Light Pole? A Comprehensive Guide to Street Lights

As navigators of urban and suburban landscapes, we often take street lighting for granted, oblivious to the fact that they light our way home each night. Understanding the height of street lights, or how tall are street lights, and their lifespan goes a long way in appreciating the science and careful thought that goes into the positioning of these integral public amenities. This article provides an informative guide on street light pole height, how tall a light pole is, and their expected lifespans.

Understanding Street Lights

Let's start by answering one of the most common queries - what is a street light? The origin of street lights dates back to the 4th century in the city of Antioch where they served as safeguards against pedestrian accidents. Initially, the system utilized coal gas as the primary fuel, but the modern era has ushered in new technologies, including LED and high-intensity discharge lamps, employed in beacon lights, roadway lights, and cycle path lights.

Street lights, also known as light poles or lampposts, are towering fixtures providing illumination along roads or pathways. Activated automatically through light-sensitive photocells at dusk, dawn, or the onset of poor weather conditions, they contribute significantly to public safety.

Types of Street Lamps

To determine how tall is a street light pole, it's crucial to recognize various street lamp types, divided by the light source and the location of use. Light sources include LED street lamps, induction lamps, energy-saving lamps, high-pressure sodium lamps, and metal halide lamps. On the location aspect, we have ordinary street lamps, high-post street lamps, courtyard street lamps, and landscape street lamps, among others.

The function of the light also determines the choice. If illumination is the primary goal, street lights - which are usually more than 5 meters in height - are used. For landscaping purposes, garden lights of about 3 meters are preferred.

Standard Heights of Street Light Poles

The standard size of the street light pole or standard light pole height can range from 2.4m to 15.2m (28 – 50 ft) (dimensions.com). The specific street light height depends on the road's width. If the light is one-sided, the height of a light pole should match the road's width, or be less than 1 meter wider. 

A typical correlation exists between the power of common LED street lamps and the pole height: 100W street lamps stand below 15 ft, 150W lamps under 22 ft, 200W lamps below 28 ft, and 300W lamps under 35ft. For garden lights, pole height generally ranges from 3 to 4 m（9.8-13.1 ft）, while high pole lights, also named high-mast, are usually over 15 m (49.3 ft).

Factors Influencing Street Light Pole Heights

The height of street lights isn't chosen randomly. Various considerations include location requirements, traffic density, road width, street lamp spacing, and the type of light source.

A. The location of installation impacts the street light pole height. Rural roads, county roads, and provincial roads have different pole heights, mainly correlating with road width.

B. Traffic density and vehicle type also influence the height of a light pole. Areas with larger vehicles require higher street lights while zones with fewer large vehicles can have lower street lights.

C. The pole height also needs to be proportionate to the road's width and the spacing between street lamps. Street lamps' longitudinal spacing typically falls between 30 to 50 meters, influenced by factors such as the LED street light's power and the road width.

D. The type of light source directly influences the height of street light poles, primarily due to differences in light intensity, distribution, and efficiency among different light sources.

• High-intensity light sources like Metal Halide and High-Pressure Sodium lamps can illuminate broader areas, permitting taller poles and wider spacing between them. However, these sources tend to emit light in all directions, creating unwanted light pollution and wasting energy.

• Conversely, LED (Light Emitting Diodes) sources, which have gained popularity recently, are highly energy-efficient and can direct light precisely where needed. They generate uniform, bright light, reducing the dark spots between poles. This directional lighting ability allows for lower pole heights and closer spacing, reducing light pollution and providing a more consistent lighting environment.

In essence, while brighter, high-intensity light sources might seem suitable for taller poles, energy-efficient and directionally-precise sources like LEDs may allow for greater flexibility in pole height and placement while maintaining or improving lighting conditions.

3 Useful Calculation Formulas and Examples

1. Calculate the Distance between Each Streetlight Pole

Formula: Spacing between each Pole = (LL * CU * LLD * LDD) / (Eh * W)

- LL: Lamp Output (Lumen)
- CU: Coefficient of Utilization Factor
- LLD: Lamp Lumen Depreciation Factor
- LDD: Light Loss Depreciation Factor
- Eh: Required Lux Level
- W: Road width

Example:
Calculate the distance between each streetlight pole with the following details:

Road Details: The width of the road is 65.62 feet (20 meters). 
Pole Details: The height of the pole is 26.25 feet (8 meters). 
Luminaire of each Pole: Wattage of Luminaries is 150 Watts, Lamp Output (LL) is 18000 Lumens, Required Lux Level (Eh) is 8 Lux, Coefficient of Utilization Factor (Cu) is 0.2, Lamp Lumen Depreciation Factor (LLD) is 0.85, Light Loss Depreciation Factor (LDD) is 0.9.

Using the formula:

Spacing between each Pole = (LL * CU * LLD * LDD) / (Eh * W)= (18000 * 0.2 * 0.85 * 0.9) / (8 * 65.62)≈ 11.99 feet (94.5 meters)

Therefore, the distance between each streetlight pole in this example is approximately 11.99 feet (94.5 meters).

2. Calculate the Wattage of Each Streetlight Luminaire

Formula: Watt of Each Street Light Luminaire = Average Lumen of Lamp / Luminous efficacy

- Average Lumen of Lamp: Calculated as (L x W x D) / (mf x cu) in the example.
- L: Required Illumination Level for Street Light (Lux per Square Meter)
- W: Width of the road 
- D: Distance between each pole
- mf: Maintenance Factor
- cu: Coefficient of Utilization Factor
- Luminous efficacy: Lumen per Watt (efficiency of the luminaire)

Example:
Calculate the streetlight wattage for each luminaire with the following details:
- Road Details: The width of the road is 32.81 feet. (10  meters)
- Distance between each pole (D) is 131.23 feet. ( 40 meters)
- Required Illumination Level for Street Light (L) is 8 Lux per Square Meter.
- Luminous efficacy is 30 Lumen/Watt.
- Maintenance Factor (mf) is 0.35.
- Coefficient of Utilization Factor (cu) is 0.8.

Using the formula:

Average Lumen of Lamp = (L x W x D) / (mf x cu) = (8 x 32.81 x 131.23) / (0.35 x 0.8)
Average Lumen of Lamp ≈ 13,146.46 Lumen

Watt of Each Street Light Luminaire = Average Lumen of Lamp / Luminous efficacy= 13,146.46 / 30≈ 438.22 Watts

Therefore, the wattage of each streetlight luminaire in this example is approximately 438.22 Watts.

3. Calculate the Required Power for a Streetlight Area

Formula: Required Streetlight Watt = (Lux per Sq.Meter x Surface Area of Street Light) / Lumen per Watt

- Lux per Sq.Meter: Required Illumination Level for Street Light (Lux per Square Meter)
- Surface Area of Street Light: Area to be illuminated (Square Meter)
- Lumen per Watt: Luminous efficacy (Lumen per Watt)

Example:
Calculate the required power for a streetlight area with the following details:
- Required Illumination Level for Street Light (L) is 8 Lux per Square Meter.
- Luminous efficacy (En) is 25 Lumen per Watt.
- Required Street Light Area to be illuminated (A) is 3 Square Meters.

Using the formula:

Required Streetlight Watt = (Lux per Sq.Meter x Surface Area of Street Light) / Lumen per Watt= (8 x 3) / 25= 0.96 watts

Therefore, the required power for the streetlight area in this example is approximately 0.96 watts.

Further Considerations for Street Light Poles

Understanding how tall a street light is doesn't end with knowing its height. Other details like intervals between lights, installation environment, light distribution, aesthetics, and maintenance are just as crucial.

1. Consistent Spacing of Lights

Street lights primarily serve to illuminate paths for pedestrians, cyclists, and motorists. If lights are unevenly spaced, resulting in a well-lit area followed by a pitch-black space, this can cause accidents. Consistent intervals between lights are essential for safety. The spacing between the two light poles should be approximately 2.5-3 times the height of the pole (innovationdiscoveries). Shorter light poles should be installed at closer intervals.

2. Environment of Installation 

The area of installation affects the type of pole needed. In coastal regions, for instance, poles should have a special finish to prevent corrosion from salt water.

3. Distribution of Light

Even with well-lit streets, obstacles like trees or tall buildings can create dark spots. It's critical to account for these when planning the placement of street lights.

4. Aesthetical Values of Street Light Poles

Today, street light poles don't just serve functional purposes. Decorative lighting poles highlight aesthetic features like statues, gardens, and fountains, adding charm and transforming otherwise mundane city spaces.

5. Maintenance of Street Light 

An average LED street light operates for around 10 to 12 hours daily, and the bulb can last approximately 50,000 hours. It's essential to replace bulbs as needed for efficient lighting, and ensure the poles are sturdy enough to support the fixtures.

Now we know that determining how tall a street light is, the height of a light pole, or how long street lights last involves a complex set of considerations, from technical aspects to aesthetic concerns. Yet, it's this careful design and thought process that ensures our streets are safe and visually appealing after sunset. With this comprehensive guide, you should have a deeper understanding of these often overlooked yet crucial elements of our daily lives.

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