Calculation of general lighting. Life safety. Calculation of artificial lighting Calculation of artificial lighting

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CALCULATION OF ARTIFICIAL LIGHTING

Luminous flux utilization factors for luminaires with fluorescent lamps

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Ministry of Education and Science of the Russian Federation

FSBEI HPE URAL STATE ECONOMIC UNIVERSITY

Department of Economics

Practical work

in the discipline "Life Safety"

Calculation of risk level

Executor:

Student of group VED-14 Dymarskaya I.V.

Supervisor:

Art. teacher Pankratieva N.A.

Ekaterinburg 2014

Introduction

Purpose of the work: Familiarize yourself with the basic concepts of life safety: danger and risk, types of risk, traumatic factor and its types; determination of quantitative hazard characteristics and methods for calculating the degree of risk.

1. Theoretical part

The life safety course examines and studies issues that are important to every person. Safety and security is a complex discipline that studies the possibilities of ensuring human safety in relation to any type of human activity. When starting to study the section “calculating the degree of risk”, you should familiarize yourself with its basic concepts from the very beginning.

Danger- these are phenomena, processes, objects, properties of objects that can, in certain cases, cause damage to human health or the environment.

Danger lies in all systems that have energy, chemically or biologically active components, as well as characteristics that do not correspond to human living conditions. It is also said that such systems have the so-called residual risk, i.e. the ability to lose stability or have a long-term negative impact on humans and the environment.

The objective basis of the danger is the heterogeneity of the “man - environment” system.

The dangers are potential. Actualization or realization of dangers occurs under certain conditions called causes. For living organisms, danger is realized in the form of injury, disease, death.

Signs of danger may include:

· threat to life;

Possibility of causing damage to health;

· violation of the conditions for the normal functioning of human organs and systems.

· violation of the conditions for the normal functioning of ecological systems

The frequency of occurrence of a hazard in the process of human activity is usually defined by the term “risk”. Let's define the word “risk”:

Risk- a combination of the probability and consequences of the occurrence of adverse events. Knowing the probability of an unfavorable event allows you to determine the probability of favorable events using the formula:

Where n- number of realized undesirable events;

N- the total number of possible undesirable events over the same period of time.

Risks can be divided into a huge number of types, but let’s consider their classification according to the type of danger and the possibility of foreseeing them.

Types of risks by type of hazard:

· Technogenic risks- these are the risks associated with economic activity human (for example, environmental pollution).

· Natural risks-- these are risks that do not depend on human activity (for example, an earthquake).

· Mixed risks-- these are risks that are natural events, but associated with human economic activity (for example, a landslide associated with construction work).

Types of risks, if foreseeable:

· Forecasted risks-- these are risks associated with the cyclical development of the economy, changing stages of financial market conditions, predictable development of competition, etc. The predictability of risks is relative, since forecasting with a 100% result excludes the phenomenon in question from the category of risks. For example, inflation risk, interest rate risk and some other types.

· Unpredictable risks These are risks characterized by complete unpredictability of manifestation. For example, force majeure risks, tax risk, etc.

According to this classification criterion, risks are also divided into regulated and unregulated within the enterprise.

One more key concept is the concept of “traumatic factor”

Injury factor- a negative impact on a person that, under certain conditions, can cause acute health problems, injury and death of the body.

Traumatic factors are understood as any man-made, natural, social impact on a person that contributes to the occurrence of damage to the skin, muscles, bones, tendons, spine, eyes, head, and other parts of the body, without being their direct cause. From huge amount traumatic factors, allowing us to assert that any activity is potentially dangerous, it is necessary to highlight the most significant group of physical traumatic factors leading to mechanical injury

Traumatic (traumatic) factors include: electric current, falling objects, heights, moving cars and mechanisms, debris of collapsing structures, aggressive and toxic chemicals; heated (cooled) elements of equipment, processed raw materials and other coolants; etc.

The results of the analysis of the causes of injury suggest that “all hazards can be controlled to a certain extent if they can be identified.”

Let's consider one problem of calculating the degree of risk of injury to a person in the following situation:

Example 1

Predict the number of deaths from fire per year in the private industrial enterprise of Yekaterinburg, if it is known that the individual risk of death from fire for workers of such enterprises is 4·10 -4 per year. The total number of implementers will be 10,000 people.

Let's use the basic formula for calculating the degree of risk to solve this problem:

In this case, R and = 4*10^(-4), N = 10*10^3, from where we find that n, which is calculated by the formula n= R and *N, will be equal 4 .

Let's also consider a table showing the risk of injury (risk of fatal outcome) per year due to various situations.

Having carefully analyzed it, we can conclude that complete safety cannot be guaranteed to anyone, regardless of lifestyle.

2. Main part

Problem 1

Problem 2

Problem 3

Conclusion

As a result of practical work No. 1 “Calculation of the degree of risk,” such concepts of life safety as danger and risk, types of risk, and the theory of the traumatic factor were studied. I learned to determine quantitative characteristics of danger and became familiar with the methodology for calculating the degree of risk. safety risk traumatic

The main goal of life safety as a science is to protect people in the technosphere from negative impacts anthropogenic and natural origin and achieving comfortable living conditions.

The means to achieve this goal is the implementation by society of knowledge and skills aimed at reducing physical, chemical, biological and other negative impacts in the technosphere to acceptable values. This determines the body of knowledge included in the science of life safety.

This discipline solves the following main tasks:

Identification (recognition and quantification) of negative impacts of the environment;

Protection from dangers or prevention of the impact of certain negative factors on a person;

Elimination of negative consequences of exposure to dangerous and harmful factors;

Creating a normal, that is, comfortable state of the human environment.

Complete safety cannot be guaranteed to anyone, regardless of lifestyle. Therefore, we can only take measures to reduce risks; we will not be able to isolate ourselves from them completely. The following risk reduction measures have been developed:

Quitting bad habits;

Extremely careful behavior on the roads to avoid accidents;

Be careful when cooking, using gas stoves, lighters, matches or other flammable and flammable items indoors;

Use only fresh and natural products for food, eliminate synthetic products from the diet as much as possible;

Do not use firearms unless absolutely necessary and near other people;

Much more.

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However, there is no need to invent anything; standards for artificial lighting have been developed and adopted to ensure human well-being. This includes standards, GOSTs and recommendations. Not only the health or productivity of the worker, but sometimes even his life often depends on their strict implementation. If a project is being developed for artificial lighting of selected production premises, the basic calculation of indicators is based on the data of the domestic SNiP number 23.05–95.
Globally, lighting is divided into three types: natural (from the sun through windows), artificial (lamp) and mixed (or combined) - both types together. On large manufacturing enterprises Where labor protection and safety requirements are strictly observed, it is very important to ensure a balance of room illumination when using combined light sources: artificial and natural. Therefore, when planning workshops, you should definitely take appropriate measurements.
Well-planned lighting contributes to the excellent well-being of workers, which has a positive effect on their productivity, fatigue and the risk of injury are significantly reduced. Therefore, before installing lighting devices, specialized specialists must carry out a calculation of the illumination of specific production premises.

A qualitative calculation should take into account not only room layout factors, but also the specific location of production facilities relative to the cardinal points, the level of natural insolation at different times of the year, the color and material of buildings.

When determining the intensity of general lighting in premises, natural radiation from the sun must be taken into account. Therefore, the number and size of windows in the rooms are always taken into account. When calculating the power of lamps, an adjustment is also made for natural contamination of window surfaces and lamp shades. By the way, regular washing of them is recommended, because... accumulated dust significantly reduces the intensity of the lamps (or the penetration of sunlight through dirty windows).
As a rule, industrial premises have little natural light due to the small number of windows and the discrepancy between ceiling height and length. Therefore, coefficients are always introduced to correct these shortcomings.
For very dusty or humid industrial premises, it is recommended to choose luminaire models with a dust and moisture protection level - IP, at least 44 (or better with IP 54-55). They are reliably protected from aggressive influences and will last longer than conventional non-sealed products.
The specificity of the work performed in production also plays a big role. So, if technological operations require increased precision from personnel (when working on complex machines, in small assembly shops, in drawing, design offices, etc.), it is imperative to increase the level of general lighting. It is also necessary to provide for the possibility of its zonal amplification. For this purpose every workplace should be equipped with a directional light source, the flow from which each employee can adjust to suit themselves.
In order to save energy, it is unacceptable to use only local lighting near each workplace. Since the employee will not see anything outside his light zone that grossly contradicts safety rules. And when he shifts his gaze, his eyes will become overstrained due to a sharp change in light levels. As a result, a person’s visual acuity will rapidly decline, fatigue will increase, and productivity and quality of work in general will decrease.
In addition to the specifics of the work, it is necessary to take into account the characteristics of the personnel themselves: average age, degree of workload with intense visual work, state of health. So, if there is a disabled employee in the room, you need to provide him with a separate lamp, based on the cause of the disability.
When calculating lighting fixtures for industrial premises, it is imperative to include autonomous emergency lighting, which will operate from a backup line, even if the enterprise is de-energized. This is vital so that workers have the opportunity to stop the equipment and leave the building if any extreme circumstances arise: smoke, fires, toxic emissions, etc.

The most common way to determine the total light filling of a room is to calculate the corresponding coefficient. It allows you to calculate the degree of illumination required for each specific room, on the basis of which you can select lamps of suitable power in the required quantity. Measured in lumens (or lux per unit area).
The indicator is calculated using the formula:

Where,
Z – illumination unevenness coefficient. It displays the ratio of average illumination to the minimum possible. Provided that the lamps are installed in a row, it is 1.15 (for lamps with incandescent filament) and 1.1 (for fluorescent lamps);
S – room area;
Kz is a safety factor that corrects for the degree of dust in the room, due to which the lamps shine much more dimly. The value is taken from the same SNiP (Table 3). A simplified copy is attached below.

Stock of lamps

En – standard illumination for a specific room (in lux). It is determined based on the specifics (class of work) according to SNiP 2305-95 (can be found in Table 1);
This standard depends on the specifics of the work performed indoors; it can also be taken from SNiP. The average table of standards is given below.

Lighting options

η – calculated indicator of the use of luminous flux. It displays how much
light from the lamps falls on the plane of the working surfaces.

This calculation involves determining the room index - IP, which is determined by the formula:

where S is the area, hр is the estimated installation height of the lamps (m), A and B are the length of the walls of the room (m).
In turn, hp is found as the difference between the height of the room - Bk, the height of the working surface above the floor level - hpn (usually equal to 0.8 m) and the overhang of the lamp hc (or the distance from the ceiling to the burning lamp, often taken as 0.5 m)

hp = Vk - hpn - hс

Having determined all the presented parameters, you can calculate the standard number of lamps. To do this, we divide the resulting light filling coefficient F by the standard flow of the selected luminaires guaranteed by the manufacturer - Fl.

To better understand the principle of determining general illumination, let’s perform the calculation using the example of a room with dimensions of 10 m by 15 m, with a ceiling height of 4 m, with light ceiling and wall surfaces, a gray floor and an average level of dust. The class of work performed is medium accuracy. It is planned to install fluorescent lamps with a power of 18 W, 4 pieces in each lamp.
We go from the opposite - first we find the estimated installation height:

hp = 4 – 0.8 – 0.5 = 2.7 m

Determine the room index:

Now we find the value of the luminous flux utilization factor:

In order not to bother with calculations, the table below can be used to determine this parameter. Only in this case it is imperative to take into account the degree of reflection of all surfaces. In our case, these coefficients are: for the floor - 0.3, for the walls - 0.5 and for the ceiling - 0.7. At the intersection of the column and the column there will be the desired indicator.

Reflection of light

Now you can start calculating the light intensity of the room

F==143709 lumens

The approximate luminous flux coming from four fluorescent lamps with a power of 18 watts each was taken from the table:

Luminous flux of lamps

The total number of lamps required for general illumination will be:

Cl = = 40 lamps

In principle, the result is fully consistent with the generally accepted office standard for Armstrong-type systems - one lamp per 4 meters of room area. These calculations were made with lighting at 300 lumens, more similar to natural lighting. It is clear that for work that requires high precision with enhanced visual work, you need to use either more powerful lamps, or simply a larger number of them.

The number of lamps obtained in our calculation, you will agree, turned out to be very significant. And this is only for one production facility, but there could be dozens of them. The costs of purchasing lighting fixtures and electricity are considerable. Therefore, it is more rational to immediately spend more, but purchase modern energy-efficient systems. They will significantly reduce energy consumption with equal light output.

Energy efficient systems

A striking example is a high-tech alternative - LED lamps. They are visually no different from popular raster systems with fluorescent light sources. Therefore, you don’t even have to redo the ceiling. However, they are many times more economical, since they consume half or even three times less energy.
In addition, pleasant bonuses are: instant start-up, absence of flickering, which housekeepers often suffer from, resistance to frequent on-off switching and an unprecedentedly long service life, without the need to replace consumables for more than five years.
LED systems, as a rule, more than pay for themselves after the first years of operation, and the more such lamps are installed, the greater the economic effect.
And another seemingly insignificant measure is painting the ceilings, walls, furnishings and equipment in white (or simply light) color. This contributes to a more uniform dispersion of light in the room. And it turns out that with the same energy expenditure, the illumination intensity increases noticeably.

When performing operations on lathes and milling machines in a machine shop, workers are exposed to a number of hazardous and unhealthy factors. Let's calculate the magnitude of some of them.

In the mechanical shop of the SEPO-ZEM LLC enterprise, the LSP 02 fluorescent lamp is used for lighting. According to GOST 6825-74, the LSP 02 fluorescent lamp corresponds to a luminous flux Fl = 3380 lm. The number of lamps in the lamp is 2 pieces, the number of lamps is 20 pieces. We will calculate the luminous flux of one lamp and determine whether this type of lamp is suitable for a given room according to safety standards.

Illumination in the machine shop E, lux is determined from the formula:

where E is the illumination of the workshop lux;

S - room area, m2;

K - safety factor, taking into account the contamination of lamps and the presence of dust, smoke, soot in the air, K = 1.8;

z - correction factor taking into account uneven lighting; z = 1.1;

h - coefficient of utilization of the luminous flux of lamps, depending on the efficiency and the luminous intensity distribution curve of the lamp, the reflection coefficient of the ceiling ср, walls сс and floor?р (сп = 50%, сс = 30%, ?р = 10%), the height of the lamp suspension and room indicator i;

N - number of lamps, pcs;

m - number of lamps in the lamp, pcs., m = 2

where A and B are two characteristic dimensions of the room, m; A = 20 m, B = 10 m;

Нр - height of lamps above the working surface, m.

Нр = Н - hc - hp

where H is the total height of the room, m, H = 9 m;

hc - height from the ceiling to the bottom of the lamp, m, hc = 0.8 m;

hp - height from the floor to the illuminated surface, m, hp = 0.8 m.

Нр = 10 - 0.8 - 0.8 = 8.4 m.

Therefore, з = 0.3

Light levels for assembly work are set in accordance with current regulations. regulatory documents for fluorescent lamps 150 lux. Therefore, the lamp used does not compromise safety and corresponds to the required lighting.

As a result of the calculations, it was established that the illumination complies with the required standards.

Noise level assessment.

The sound power level of the Vturn-X200 milling center is 76 dB. Let's calculate the noise intensity level of the machine using the formula:

L w - source sound power level, dB;

F - noise direction factor (sound energy is emitted equally in all directions, F = 1);

r is the distance to the source, m;

h - coefficient taking into account the size of the source;

w is a coefficient that takes into account the nature of the sound field in the room and depends on the ratio of the acoustic constant B room. B room = 11.1 according to the plant, coefficient w = 0.83.

We calculate the sound intensity for the point in the room where the workplace under study is located, located at a distance of 0.5 m from noise sources; 3.7 m; 6.9 m.

Let us determine the level of sound intensity at the calculated point from various sources:

· from milling machine 1, r= 0.5 m, L w = 76 dB, h=4.1:

· from milling machine 2, r= 3.7 m, L w = 76 dB, h=2.5:

· from milling machine 3, r= 6.9 m, L w = 76 dB, h=1.5:

We determine the total level of sound intensity in the workplace from all sources:

where L 1, L 2, L 3 are the noise intensity levels created by each source at the design point, dB.

According to SN 2.2.4.2.1.8.562-96, the noise maximum level is a total sound intensity level of 80 dB. Consequently, there is an excess of the maximum permissible level by 1.2 dB, which corresponds to the class of working conditions 3.1 - harmful. Calculation of required air exchange for removal harmful substances from the premises. In a mechanical workshop, the air in the working area contains such harmful substances as: mineral oils with a concentration of 8 mg/m3 and iron oxides with a concentration of 9 mg/m3. The amount of released mineral oil and the amount of iron oxides are calculated by the formula:

G = C * V * K, mg/h

where C is the actual concentration of the harmful substance per unit volume of air in the production area, mg/m 3 ;

V - volume of the room, m 3;

K is a safety factor that takes into account the uneven distribution of harmful substances throughout the volume of the room (from 1.5 to 2);

Amount of mineral oil released:

G 1 = 8 * 1080 * 2 = 17280 mg/h;

Amount of iron oxide released:

G 2 = 9 * 1080 * 2 = 19440 mg/h.

The required air exchange to remove harmful substances from the work area is calculated using the formula:

L = G / q out - q in,

where G is the amount of released harmful substances, mg/h;

q out, q in - concentrations of harmful substances in the exhaust and supply air, respectively, mg/m3; q inc =0, because There are no mineral oils or iron oxides in the atmospheric air.

L m.m. = 17280 / 8 = 2160 m 3 /h.

L ox.g. = 19440 / 9 = 2160 m 3 /h.

Since the required air exchanges are equal, we take 2160 m 3 /h.

Depending on the type and purpose of the room, air exchange rates are established.

where LQ is the required amount of air exchange, m 3 / h; V - volume of the room, m 3;

K = 2160 / 1080 = 2

The required air exchange to ensure sanitary and hygienic standards in the turning shop is LQ = 810 m 3 /h with a frequency of 2 times per hour.

To ensure an air exchange of 810 m 3 /h, we use a fan for general ventilation of the TKK brand (400 V), which provides an air exchange of 900 m 3 /h. To ensure local air exchange, we use PSU-2000 dust collectors with a capacity of 2000 m 3 /h.

Ministry of Education of the Russian Federation

Tomsk Polytechnic University

Dean of the IEF

"____" _____________ 2005

"____" ________________ 2005

Head Department of Electrical Safety

Prof., Doctor of Technical Sciences

Approved by the IEF methodological commission

pres. method. commissions

Associate Professor, Ph.D.

"____" ______________ 2005

Properly designed and rationally executed lighting of industrial premises has a positive effect on workers, improves efficiency and safety, reduces fatigue and injuries, and maintains high performance.

The main task of calculations for artificial lighting is to determine the required power of an electric lighting installation to create a given illumination.

The following issues must be resolved in the calculation task:

Selecting a lighting system;

Selection of light sources;

Selection of lamps and their placement;

Selection of standardized illumination;

Calculation of lighting using the luminous flux method.

I. SELECTION OF LIGHTING SYSTEM

For industrial premises of all purposes, general (uniform or localized) and combined (general and local) lighting systems are used. The choice between uniform and localized lighting is made taking into account the characteristics of the production process and the placement of technological equipment. The combined lighting system is used for industrial premises where precise visual work is carried out. The use of local lighting alone at workplaces is not permitted.

In this calculation task, the overall uniform lighting is calculated for all rooms.

2. SELECTION OF LIGHT SOURCES

Light sources used for artificial lighting are divided into two groups - gas-discharge lamps and incandescent lamps.

For general lighting, gas-discharge lamps are usually used as they are more energy efficient and have a longer service life. The most common are fluorescent lamps. Based on the spectral composition of visible light, fluorescent lamps (LD), fluorescent lamps with improved color rendering (LDC), cool white (LCW), warm white (LTB) and white color (LB) are distinguished. The most widely used lamps are the LB type. With increased requirements for color reproduction by lighting, lamps of the LHB, LD, LDTs types are used. LTB type lamp is used for correct color rendering of the human face.

The main characteristics of fluorescent lamps are given in Table 1.

In addition to fluorescent gas-discharge lamps (low pressure), high-pressure gas-discharge lamps are used in industrial lighting, for example, DRL lamps (mercury arc fluorescent lamps), etc., which must be used to illuminate higher rooms (6-10 m).

Table 1

MAIN CHARACTERISTICS OF FLUORESCENT LAMPS

Power,	Mains voltage	lamp voltage, V	Lamp current, A	Luminous flux, lm

The use of incandescent lamps is permitted if it is impossible or technically and economically inappropriate to use gas-discharge lamps.

3. SELECTION OF LAMPS AND THEIR PLACEMENT

When choosing the type of lamps, lighting requirements, economic indicators, and environmental conditions should be taken into account.

The most common types of luminaires for fluorescent lamps are:

Open two-lamp luminaires type OD, ODOR, SHOD, ODO, OOD– for normal rooms with good reflection of the ceiling and walls, allowed with moderate humidity and dust.

PVL lamp– is dust and waterproof, suitable for some fire hazardous areas: lamp power 2x40W.

Ceiling lamps for general lighting of closed dry rooms:

L71B03 – lamp power 10x30W;

L71B84 – lamp power 8x40W.

The main characteristics of luminaires with fluorescent lamps are given in Table 2.

The placement of lamps in the room is determined by the following dimensions, m:

H – room height;

hc – distance of luminaires from the ceiling (overhang);

hn = H - hc – height of the lamp above the floor, height of the suspension;

hp – height of the working surface above the floor;

h =hn – hp – design height, the height of the lamp above the working surface.

To create favorable visual conditions in the workplace and to combat the glare of light sources, requirements have been introduced to limit the minimum height of lamps above the floor (Table 3);

L – the distance between adjacent lamps or rows (if the distances along the length (A) and width (B) of the room are different, then they are designated LA and LB),

l – distance from the outer lamps or rows to the wall.

Table 2

Main characteristics of some lamps

with fluorescent lamps

The optimal distance l from the outer row of lamps to the wall is recommended to be equal to L/3.

The best options for uniform placement of lamps are staggered placement and on the sides of a square (the distances between lamps in a row and between rows of lamps are equal).

With uniform placement of fluorescent lamps, the latter are usually located in rows - parallel to the rows of equipment. At high levels of standardized illumination, fluorescent lamps are usually arranged in continuous rows, for which the lamps are connected to each other at their ends.

The integral criterion for the optimal placement of lamps is the value l = L/h, a decrease in which increases the cost of the installation and maintenance of lighting, and an excessive increase leads to a sharp unevenness of illumination. Table 4 shows the values of l for different lamps.

Table 3

Minimum permissible height for hanging luminaires

with fluorescent lamps

Table 4

The most advantageous location of lamps

The distance between lamps L is defined as:

It is necessary to draw a floor plan on a scale in accordance with the original data, indicate on it the location of the lamps (see Fig. 1) and determine their number.

4. SELECTION OF NORMALIZED ILLUMINANCE

The basic requirements and values of standardized illumination of working surfaces are set out in SNiP. The choice of illumination is carried out depending on the size of the discrimination volume (line thickness, marks, letter height), the contrast of the object with the background, and the characteristics of the background. Required information for choosing the standardized illumination of production premises are given in Table 5.

Table 5

Lighting standards for industrial workplaces

under artificial lighting (according to SNiP)

Characteristics of visual work	The smallest size of the discrimination object,	Visual work category	Visual work subcategory	Contrast of subject with background	Background characteristics	Artificial lighting
Illumination, lux
With a combined lighting system	with general lighting system
	including from the total

Highest precision



accuracy



High precision

Continuation of table 5


accuracy



accuracy



Rough (very low precision)				Regardless of the characteristics of the background and the contrast of the object with the background

5. CALCULATION OF TOTAL UNIFORM LIGHTING

Calculation of the total uniform artificial illumination of a horizontal working surface is carried out using the luminous flux coefficient method, which takes into account the luminous flux reflected from the ceiling and walls.

The luminous flux of an incandescent lamp or a group of fluorescent lamps of a lamp is determined by the formula:

Ф = En × S × Kз × Z *100/ (n × h),

where En is the standardized minimum illumination according to SNiP, lux;

S – area of the illuminated room, m2;

Kz – safety factor taking into account contamination of the lamp (light source, lighting fixtures, walls, etc., i.e. reflective surfaces), (presence of smoke in the atmosphere of the workshop), dust (Table 6);

Z – illumination unevenness coefficient, ratio Eср./Еmin. For fluorescent lamps in calculations it is taken equal to 1.1;

n – number of lamps;

h - luminous flux utilization factor, %.

The luminous flux utilization coefficient shows how much of the luminous flux of the lamps hits the work surface. It depends on the room index i, the type of luminaire, the height of the luminaires above the working surface h and the reflection coefficients of the walls rc and ceiling rn.

The room index is determined by the formula

Reflection coefficients are assessed subjectively (Table 7).

The values of the luminous flux utilization factor h of luminaires with fluorescent lamps for the most common combinations of reflection coefficients and room indices are given in Table 8.

Having calculated the luminous flux F, knowing the type of lamp, the nearest standard lamp is selected from Table 1 and the electrical power of the entire lighting system is determined. If the required luminaire flux is outside the range (-10 ¸ + 20%), then the number of luminaires n or the height of the luminaire suspension is adjusted.

When calculating fluorescent lighting, if the number of rows N is planned, which is substituted in the formula instead of n, F should mean the luminous flux of lamps in one row. The number of lamps in a row n is defined as

where F1 is the luminous flux of one lamp.

Table 6

Safety factor for luminaires with fluorescent lamps

Table 7

The value of the reflection coefficients of the ceiling and walls

Ceiling condition

Condition of the walls

Freshly whitewashed

Whitewashed, in damp areas

Clean concrete

Light wooden (painted)

Concrete dirty

Wooden unpainted

Dirty (forges, warehouses)

Freshly whitewashed with windows covered with curtains

Freshly whitewashed with windows without curtains

Concrete with windows

Covered with light wallpaper

Brick unplastered

With dark wallpaper

Quantity and power

Scope of application

Dimensions, mm

Lighting of industrial premises with normal environmental conditions

For fire hazardous areas with dust and moisture emissions

Similar to OD

Lamp type