Calculation and installation of LED floodlights with a built-in motion sensor

Recommendation points

• Defining lighting zones
• Parking area lighting
• Calculation of the required number of lighting fixtures
• Connecting LED spotlight

This article discusses the purpose of street lighting, determining the requirements for the project. Describes the possibility of using LED floodlights with a built-in motion sensor to illuminate the parking area and its self-configuration.

At the stage of project preparation, it is necessary to determine the functions that street lighting will perform. Then select the required number of lamps, their type, calculate communication lines, protection and control units.

Street lighting can be used to solve problems such as:

1. Ensuring minimal lighting of the territory (security functions).
2. Working lighting of parking areas and paths, necessary for the safe movement of a person at night.
3. Decorative illumination of a night garden, building facade, fountains and other objects.

Defining lighting zones

Consider building a street lighting system based on a conventional country house with a small plot of land.

In the above diagram:

1. Living quarters.
2. Decorative hedge and trees.
3. Outbuildings.
4. Flower beds.
5. Walking paths.
6. Fountain.
7. Parking area.
8. Doors, gates, gates.

Let’s define the requirements for the functionality of the street lighting system:

1. Automatic lighting of the parking zone when opening a gate or street gate at night with the ability to independently switch on the lighting.
2. Automatic switching on and off the emergency lighting in the dark.
3. Complete and economical lighting of the site.
4. Illumination of flower beds.
5. Fountain lighting.

Parking area lighting

P – LED floodlights with a built-in motion sensor

To ensure that the light is automatically turned on when a gate or door is opened, you can use spotlights with a built-in motion sensor. For these purposes, a significant number of lighting fixtures are on sale, made on the basis of incandescent, halogen, LED, etc. lamps..

The classic motion sensor has three knobs that regulate its operation:

1. Time – glow time after triggering. The built-in timer can delay the switching off of the luminaire from a few seconds to 5-10 minutes.
2. “Moon and Sun” – adjusts the operation of the spotlight in accordance with the ambient light. At the extreme point of the regulator position (“Sun”), the spotlight will not turn on in any light. By moving the regulator to the position closer to the “Moon”, you can set the optimal operation of the searchlight only in the dark.
3. “Sensitivity” – this knob allows you to adjust the sensor response range and exclude the triggering of a searchlight when moving, for example, pets.

When choosing a spotlight, in addition to its functionality, it is necessary to pay attention to the degree of dust and moisture resistance of the case. Most of the models on the market are IP44 rated to withstand splashes of water from any angle and fine dust.

If the floodlight can be exposed to jets of water (for example, when cleaning the facade of a building), then it is worth giving preference to models with IP65, 66 or 67. The cost of the floodlight ranges from 1000 to 2500 rubles, depending on the manufacturer and the power of the emitter.

Calculation of the required number of lighting fixtures

Here is an example of calculating the required number of lighting fixtures, depending on the degree of illumination of the site. For this, various methods can be used, but the simplest and most understandable of them are calculations performed by the method of the utilization factor of the luminous flux and the method of specific power.

The calculation of the number of luminaires using the luminous flux utilization method is performed according to the formula:

• N = E x S x z x k / F x ?, Where:
• ? – the utilization factor of the light emitted by the device depends on the reflectivity of the objects surrounding the light source;
• E – required minimum illumination, set in lux (lx);
• S – area of ​​illuminated space, m²;
• N – the number of installed luminaires;
• z = E_Wed / E_min – takes into account the unevenness of the lighting produced by the electrical appliance. For incandescent lamps, the coefficient is 1.15, for fluorescent and LED lamps – 1.1;
• F – luminous flux emitted by one lamp, lm (lumen);
• k – a safety factor used to take into account possible dusting of the lamp and reduce the amount of light emitted by it during prolonged use (aging). For fluorescent lamps, this coefficient can reach 1.5. For incandescent and LED lamps – 1.2-1.3.

Let’s calculate the area of ​​the parking zone:

• S = a x b = 10 x 12 = 120 m²

Using the reference data, we will determine the luminous flux emitted by one lamp, or we will perform an approximate calculation:

• F = P x K, Where:
• R – lamp power, W;
• TO – luminosity factor per 1 W of power.

For incandescent lamps, K = 20 lm / W;

For gas discharge (energy saving) lamps, K = 80 – 90 lm / W;

For LED lamps, K = 70 – 130 lm / W.

For a 30 W LED floodlight with a built-in motion sensor, the minimum luminous flux can be determined by the formula:

• F = 30 x 70 = 2100 lm

The utilization factor of the light emitted by the device can be found in the instruction CH 541–82. For our case, the surface of the site is assumed to be made of light gray concrete, for which ? = 50%.

We select the minimum illumination within 10 lux, which corresponds to the standards for lighting sites where it is not required to perform precise work and stay for a long time.

Having picked up all the necessary data, we calculate the minimum number of lighting devices for automatic parking lighting:

• N = E x S x z x k / F x? = 10 x 120 x 1.1 x 1.25 / 2100 x 0.5 = 1.57 pcs.

To provide comfortable lighting for a parking area of ​​120 m2² you will need two LED floodlights, 30 W each.

We will perform a verification calculation using the power density method. The required power of installed incandescent lamps is calculated using the formula:

• P = w x S, Where:
• w – specific power of general uniform illumination;
• S – room area.

Specific power is a reference value and for different types of premises it can vary from 1 to 12 W / m². For parking lots, this value ranges from 1 to 3 W / m².

• P = 2 x 120 = 240 W

Since this power corresponds to the use of incandescent lamps for lighting, which have a lower luminosity in comparison with LED ones, this value must be divided by a correction factor. For LED lamps – 5, gas-discharge lamps – 4.

• P = 240/5 = 48 W

This calculation confirms the possibility of using two LED floodlights selected for illumination with a total radiation power of 60 W.

Connecting LED spotlight

Connection can be done in two ways:

1. Direct directly.
2. Through an adapter junction box.

For direct connection it is necessary to unscrew the seal and unscrew the four fixing screws in the corners. After that, on the terminal block located inside the spotlight, it is necessary to replace the “native” wire with the one used for connecting.

For installation work, you need to use a double-insulated wire, preferably copper, with a conductor cross-section of at least 1 mm² (optimally 1.5 mm²). This guarantees reliable operation of the device for a long period of time, even with constant exposure to negative external factors..

When connected using a feed-through terminal box, all electrical wiring takes place inside the box. The selected junction box must meet the requirements of dust and moisture resistance.

In a similar way, any lighting is calculated, both indoors and outdoors, only the specified amount of illumination changes, at which a person will be comfortable working or relaxing.

Note:when developing street lighting, it is necessary to take into account not only the effect of moisture, but also climatic conditions. Do not buy equipment for outdoor installation that cannot withstand winter cold or summer heat.

Competent use of various sensors and LED lamps allows you to reduce the cost of lighting the site and extend the life of the uninterrupted operation of lighting devices.