How Many Watts of Street Light Do You Need?

Now the led street light has great optics and lense, the number of led watts is different from the traditional high-pressure sodium lamp wattage, such as high-pressure sodium lamp 100w, equivalent to led36w, 150w equivalent to led 60w and so on. Commonly used led wattages are: 5w, 10w, 15w, 20w, 30w, 40w, 50w, 60w, 80w, 100w, 120w, of which 60w or less is for ordinary LED lighting, 60w or more for mirror or lens.

The special structure of LED lense:

Most people are familiar with LED light. The benefits of LED usage are phenomenal. They are energy efficient, consuming 90% less energy than incandescent bulbs, and are long lasting. Consumers and businesses alike have been implementing a transition to LED in everything from TVs, to billboards, to ads on public transportation. The LED Display has become a part of our daily visual landscape.  Even so, they come with their own technical challenges.

The primary optic for an LED only gives directional light 180 degrees. Because it is too broad of a light for most applications, the LED light begins to lack intensity over distance. To alter the radius and get a more focused intensity, it is necessary to add a secondary lens and/or reflectors.

Consider light moving in parallel rays. A convex lens has a surface that bulges outward and will make rays converge at a specific spot, a focal point. A concave lens has a surface that curves in, making those parallel lines curve outward, away from a central point. Focused LED light can have a secondary optic placed on it called TIR lenses. TIR lenses fit over the dome top of the LED. They combine the benefits of a lens and a reflector. Taking the light beam in, and reflecting it back in a manner similar to the function of a concave lens that sends the rays outward and apart, rather than converging.

When coupled with a lens to project the light emitted from an LED, it is not limited by a 180 degrees.  Once a secondary lens is in place, the LED can provide the same element of lighting function as the traditional incandescent bulbs that naturally emit a 360 degree light.

Three factors that should be considered when selecting wattage:

A high-pressure sodium street light can draw up to 1000 watts, and an incandescent light used in the 1900s needed 320 watts. Some LED street lights require only 73 watts and, according to the U. S. Department of Energy, produce a higher quality of light.

Fluorescent bulbs were used in street lights from the 1950s to the 1970s, but because of their low reliability and size, they gave way to high-pressure sodium lights rated at 250 watts. A metal halide street light draws 400 watts and gives true, white light. Mercury vapor lights also appeared in the 1950s, with 100-watt bulbs used in street lights, but were banned in 2008.

LED street light wattage selection is generally selected according to road width and pole height, or according to road lighting standards, the following small series will be analyzed.

The analysis is carried out in the following three aspects.

First, measuring the light poles’ height:

the power of the light source has a direct relationship with the height of the light pole. In principle, the higher the light pole, the greater the power of the light source, although a small wattage light source is installed on the higher street light. It can also illuminate the ground, but this ratio is not ideal both in terms of brightness and illumination.

Second, choosing LED street lights or other lights :

At present, the light source used in street lighting can be basically divided into two categories, namely LED lights, and high-pressure sodium lamps. The power of these two lamps is completely different under the same illumination range and the same illumination brightness. We know that LED lamps can be called synonymous with “green energy-saving light source”. Its energy-saving effect is well known. For example, a set of 7-meter-high street light poles, with a 40W LED lamp head and a 110W high-pressure sodium lamp. The brightness is almost the same.

Third, considering the installation environment, rural areas or cities:

whether it is equipped with high-pressure sodium lamps or metal halide lamps is also LED energy-saving lamps, the use of environmental factors will also affect their power, such as the installation of street lamps in rural areas and installed in the city center, even in two regions The height of the installed poles is exactly the same, and the configuration of the light source will be completely different. Why do you say this? First of all, the traffic volume in the city center is relatively large, and the time spent walking at night is relatively long. Lighting brightness requirements are also relatively high, this environment must be installed with a high-power light source. The countryside is different. There are very few people who go out to play at night. A little light can meet the brightness requirements. In this case, the light source with a small power point is no problem, and it is cheap and power-saving.

The rough estimate wattage corresponds to the pole height and road width:

10w, suitable for pole height 2.5m-3m

15w, suitable for pole height 3m-4m

20w, suitable for pole height 5m-6m (5m suitable for road width 6-8m, 6m suitable for road width 8-10m, 2 lanes)

30w, suitable for pole height 6m-7m (suitable for road width 8-10m, 2 lanes)

40w, suitable for pole height 6m-7m (suitable for road width 8-10m, 2 lanes)

50w, suitable for pole height 6m-7m (suitable for road width 8-10m, 2 lanes)

60w, suitable for pole height 7m-8m (suitable for road width 10-15m, 3 lanes)

80w, suitable for pole height 8 meters (suitable for road width 10-15m, 3 lanes)

100w and 120w, suitable for pole heights above 10-12 meters

Lighting standard of LED street light

There is one thing you need to consider, many places have their local road lighting standards. For example, our local road lighting design standards clearly stated : the average illuminance of the expressway is 20lx, the uniformity is 0.4, the average illuminance of the main road is 15lx, the uniformity is 0.35, the average illuminance of the secondary trunk is 8lx, the uniformity is 0.35, the average illumination of the branch is 5lx, uniformity 0.3. If you still don’t know how to choose a proper watt, pls feel free to contact us.