Why High Pressure Sodium Light Bulbs are Used in Street Lighting

If you are looking for an outdoor lighting solution, high pressure sodium light bulbs are likely to be the perfect answer. They have many qualities that make them suitable for outdoor use, which is why they are the most commonly found bulb in street lighting. These light bulbs offer the perfect mix of benefits for city street lighting as they are very efficient, have a long expected lifetime, and are affordable.

First off, these bulbs are very efficient compared to other varieties of lighting, which means that their purchase is an investment that will continue to pay for itself. They produce more light, with less energy, than any other type of lighting available.

High pressure sodium, or HPS, bulbs are available in a range of watts from 35 to 200 and in some cases are available all the way to 1000 watts. However, what makes these bulbs stand out in terms of efficiency is their ability to produce between 100 and 150 lumens per watt.

This means that a 200 watt bulb is able to produce approximately 25,000 lumens. This high light producing power makes them suitable for street lights, as well as security lights, where they are required to flood a large area with light. The use of HPS bulbs in these situations mean that less lights, less light poles and fewer cables are needed to suitably illuminate an area, which is one reason for their common use.

For comparison, a fluorescent bulb is likely to provide just 50 lumens per watt, so 2 or 3 times as many watts would be necessary.

In addition to their high energy efficiency, these bulbs also have a very long expected lifetime compared to other comparable bulbs. HPS bulbs can last approximately 24,000 hours.

A long expected lifetime is an important characteristic for their use in street lighting and means they need to be replaced less often. Whereas in the home or commercial environment changing a bulb is simple, for street lighting it is a lot more expensive and complex. Having to replace bulbs less often can save both time and money on labor and equipment.

A bulb that lasts 24,000 hours, if working for 12 hours each night as a street light, could last 2,000 days, or almost 5 and a half years. Again to compare this to the average household bulb, incandescent bulbs need replacing approximately every 1000 hours of use.

HPS lights can often be distinguished as a result of their yellow glow with additional hints of red and no shades of blue. It is said that this shade of light is most similar to that which we get from the sun and is therefore logical that this type of light be used to illuminate city roads.

The effect of driving in this type of light is more comparable to drivers' normal frames of reference than it would be driving in a pure white or blue tinted light. As a result, drivers are better able to approximate distances and speeds for safer night time driving.

The shade of their glow also makes HPS lights useful as grow lights, which is one of their other usages. This is another result of the shade range they deliver being close to that of the sun, meaning that plants are able to use this light to grow in indoor conditions.

All of these characteristics mean that high pressure sodium light bulbs are perfect for street lighting, which is their most common use. Due to their high levels of light and long expected lifetimes, they are able to save local governments the additional costs involved with maintaining extra street lights and replacing bulbs more frequently. They can also be used in a wide manner of other outdoor uses to meet almost any need.