Streetlights: 9 Important Answers for Beginners

In this article I will answer 9 important questions about streetlights. Let’s get started.

How do streetlights work?

Streetlights works at night hours and turns off at daylight. The working principle is simply by using an LDR based photo cell. The LDR represents light dependent resistor, its resistance value depends on the lighting falling on it. Using this lighting sensitivity we can control the lights on and off. Let’s go in some details.

Street lights have built-in lamps and power inlets. The street light will operate when you connect the power source to the street lamp’s power inlet. In most instances, the street light has a box on the lower part of the pole. It has an MCB that turns it on.

Street lights are a common fixture on poles type standings. However, they vary in the type of voltage they’re supplied with and the fixture they are. They are typically fed by an individual photocell inside the fixture or an electrical source that includes controls for rows of lights.

The most prominent part of streetlights is Cadmium Sulphide photoresistor or a CDS cell. The CDS cell can alter the resistance of a circuit based on how much light shines upon it. If a lot of light falls on the CDS cell, the resistance is low, meaning it can conduct electricity effectively. When there isn’t a lot of light, the photo-resistor is an excessive resistance, meaning that there isn’t much current flow.

This variation in current could be used to regulate the relay. Relays are an electromagnet switching device; when the electromagnet is operating at a large current (lots of light hitting the photoresistor in daylight), it opens the switch into an open position so that there is no flow of current into the streetlight.

When it’s dark, not much electricity can flow through the electromagnet, so the switch is closed and lets electricity be transferred to the streetlight by turning it on.

When do streetlights turn on?

There isn’t any set time. It can change throughout the year for any particular area, as the length of the day is different. Local authorities may operate the lights from dusk until dawn or sunset to sunrise. As you know, it depends upon the light falling on the photocell.

Some shut them down after midnight when people can reasonably be expected not to require these lights. Modern streetlights are equipped with light sensors and can come in the dark, even daylight hours.

It varies based on the location you live in and how they are managed. Suppose they’re centrally controlled, and local authorities are in charge.

In that case, they can give this information and if the lights are equipped with individual sensors for dusk to dawn that turns on between 20 and 30 minutes before sunset and shut off about 30 to 40 minutes before sunrise. Time for dusk and dawn for your city can be found online.

Why do street lights randomly turn off and then turn on again?

It is true that the temperature of streetlights gradually increases, which can result in lamp damage because of overheating. Due to overheating sometimes, the street lights are randomly turned off, and after cooling down, it turns on after some time.

The primary factor determining if the streetlight for outdoor use is of good quality is the heat dissipation performance of the light.

The issue of heat dissipation is one on which lamp heads have to keep an eye. Because of the demanding requirements for the luminosity of street lamp, the use environment is rough. If the problem of dissipation of heat is not appropriately addressed and efficiently, it can cause lamp aging and decrease stability.

You may noticed that the streetlights turn off or on when you walk by! You are not the only one who noticed so. The above explanation is one of two reasons. i.e the turn off or on is due to overheating and the below reason.

Why do streetlights turn on and off when I walk by?

The light is switched on or off whenever you drive or walk under the light. This may sometimes happen due to a faulty streetlight (you’ve likely noticed it happening to you at least once every once in a while); The phenomenon commonly referred to as street lamp interfering, also known as SLI.

maybe a psychic phenomenon that is only acknowledged and researched. As with many wonders of this kind, there is almost entirely the result of anecdotes.

However, A person who got effect by a streetlight is known as a Slider. Sliders say they experience it regularly. Of course, it’s not the case every time at every streetlight, but it happens often enough to cause them to think that something strange is happening.

Do streetlights have timers?

The basic streetlights control panel depend on photo cell based on LDR. However some control panels of street lights are controlled by timers typically utilize an electronic clock integrated into the system. The clock switches the street lights ON in the evening, then OFF in at early morning according to the timer’s settings.

Some designs feature the timer to be slightly different and differ somewhat from day to day, thereby keeping the lights up for longer times during the winter and shorter duration in the summer.

There are two different ways streetlight’s function. It depends on the mechanism implemented on the streetlights. Certain countries employ timers to control streetlights and some countries utilize photodetectors to regulate them.

Why some street light orange and some are white?

Orange streetlights are High-pressure sodium lamps, while white lamps are LED lamps.

The majority of streetlights are colored orange due to an element called sodium. When stimulated by the energy source, the sodium produces a great deal of light that is orange, making it an affordable and effective way to light up a large area.

High-pressure sodium lamps are utilized worldwide to light street lamps because they can produce a significant amount of light while using less power. Also, don’t think about what’s the most suitable for drivers. Street lamps are colored orange, not to aid in seeing better, but because they are less expensive to operate.

The street lights that emit white light used LED lights.  LEDs used in streetlights typically emit white light; it is used significantly where white entire visible spectrum is needed; it cost high as compared to sodium lights that’s why its use has become rare.

Why does street light turn on in fog?

When we don’t do correct settings of photocell according to the Hazy or Foggy season, then on facing the foggy/hazy weather condition, it will turn on the street light to consider the night due to darkness.

The best street lighting fixtures for outdoor use come with a photocell installed by the manufacturer and inform the street light when it’s time to start operating. Because they sense ambient light levels, photocells automatically adjust to seasonal changes in the day/night cycle, don’t need to be seasonally adjusted like a time controller.

The function of some advanced photocells is adjustable; you can choose the light level that fits your local situation.

Knowing the primary function of led street lights with a photocell and finding out how these products enhance the street lighting system will give you a deeper understanding of energy conservation and help you make excellent lighting solutions.

How are street light powered?

Most streetlights are powered by high-voltage AC mains; however, occasionally, rechargeable batteries are utilized in solar-powered street lamps.

Streetlights are usually high-powered when located near a highway; however, sometimes low-power lighting is used in pedestrian and park areas.

Additionally, several panels could be used as a centralized energy source in a separate area and provide electricity to numerous streets lights.

Why do streetlights take some time to glow after switching on?

High-pressure sodium and Metal-halide lamps need warm time before complete glow. That’s why it takes some time to glow after switching on.

In fact this warming up time is one of the disadvantages of high-pressure sodium and metal-halid lamps.

Some types of energy-saving lamps are available at the moment to come with a specific warming time that’s why it takes some time to glow after switching on. The reason for this is the LED transformer, which could cause delays that can last up to 5- to-20 seconds when the lighting switch is pressed. The reason behind this delay is similar to that for a line-voltage lighting source LED.

The circuit inside the LED transformer includes several capacitors for energy storage in an intermediate manner. The circuits used in some transformers include huge capacitors.

As a result, they recharge relatively slowly when they switch on; once the charging process is complete, the transformer’s voltage output will be released to the low voltage LEDs.

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