Nom 025 STPS 2008

NOM-025-STPS-2008
CONDITIONS OF LIGHTING IN THE

WORK CENTERS
INDEX
• 1. Objective
• 2. Field of application
• 3. References
• 4. Definitions
• 5. Obligations of the employer
• 6. Obligations of workers
• 7. Lighting levels for visual tasks and work areas
• 8. Recognition of lighting conditions
• 9. Evaluation of lighting levels
• 10. Control
• 11. Maintenance
• 12. Study Report
• 13. Surveillance
• 14. Bibliography
Objective
To establish the lighting requirements in the areas of the work centers, so
that the amount of lighting required for each visual activity is counted, in
order to provide a safe and healthy environment in the accomplishment of
the tasks that develop the workers.
NOM-025-STPS-2008
Field of application: This standard governs all the national territory and applies to
all work centres.
References: For the correct interpretation of this Standard, the following Mexican
official standard should be consulted current or the one that replaces it:
NOM-008-SCFI-2002, General system of units of measurement.
NOM-025-STPS-2008
Definitions: For purposes of this Standard, the following definitions are established:
4.1. Work area:

This is the site of the work center where a worker usually develops his activities.
4.2. Labour authority, Labour authority:

The competent administrative units of the Secretariat of Labour and Social welfare,
carrying out inspection functions in the field of occupational safety and health and
the corresponding entities Federal District, to act in aid of those.
4.3.Brightness:
The luminous intensity that a surface projects in a given direction, per unit of area.It
is recommended that the ratio of shines in industrial areas of no greater than 3:1 in
the workplace and anywhere in the field of vision no greater than 10:1.
Definitions
4.4. Work centre:
All places such as buildings, premises, installations and areas where production, marketing, transport
and storage or servicing activities are carried out, or in which workers who are Subject to a working
relationship.
4.5. Critical Lighting Condition:

work site lighting deficiency or very high levels that may well require an additional worker's visual
effort or cause glare.
4.6. Glare:
It is any brightness that causes discomfort and that causes interference to vision or visual fatigue.
4.7. Complementary lighting:

This is provided by additional lighting to the one considered in the general lighting, to increase the
level of illumination in a given area or work plane.
Definitions
4.8. Special lighting:
This is the specific amount of light required for the activity which, according to the nature of
the same, has a higher visual requirement of 1000 lux or less than 100 lux, for the speed of
operation of the eye (size, distance
and Colors of the visual task) and the accuracy with which the activity is carried out.
4.9. Illumination; Illuminance:

Is the incident luminous flux ratio on a surface per unit area, expressed in luxes.
4.10. Localized illumination:

This is the one provided by a lighting designed only to provide lighting on a work plane.
4.11. Luminaire; Fixture:

Lighting equipment that distributes, filters or controls the light emitted by a lamp or lamps,
which includes all the accessories necessary to fix, protect and operate those lamps, and
those necessary to connect to the electrical circuit.
Definitions
4.12. Luxmeter; Illumination Meter:
It is a tool designed and used to measure levels of illumination or illumination, in luxes.
4.13. Lighting Level:

Amount of luminous flux per unit of area measured in a work plane where activities are
carried out, expressed in luxes.
4.14. Working plane:

It is the horizontal, vertical or oblique surface, in which workers generally develop their
work, with specific lighting levels.
4.15. Focal points of the luminaires:

it is the vertical projection of the lamp to the plane or work area with inclination of 0 º, which
contains the direction of the beam of light.
Definitions
4.16. Reflection:
It is the light that affects a body and is projected or reflected by its surface with the
same angle with which it influenced.
4.14. Lighting system:

It is the set of luminaires of an area or work plane, distributed in such a way that
they provide a specific level of illumination for the accomplishment of the activities.
4.15. Visual task:

Activity that develops under certain lighting conditions.
Employer obligations
Obligations of workers
Lighting levels for visual tasks and work areas
Recognition of lighting conditions
Evaluating lighting levels
Control
If the results of the evaluation of the lighting levels were detected areas or jobs that shine
the worker, control measures should be applied to prevent the glare from affecting it.
If the measurement result shows that the lighting levels in the work areas or visual tasks are
below the levels the necessary control measures must be taken, among others, to maintain
the luminaires, to modify the lighting system or its distribution and/or to install additional or
localised lighting. For this last control measure, where more illumination is required, the
following aspects should be considered:
(a) Avoid direct glare or reflection on the worker;
(b) To select a visual background suitable for workers ' activities;
c) Avoid blocking the lighting during the performance of the activity, and
D) Avoid areas where there are sudden changes in lighting.

Maintenance
The following must be taken into account in the maintenance of the
luminaires:
Cleaning of luminaires;
b) The ventilation of the luminaires;
c) The replacement of the luminaires when they cease to function, or after

the default number of operating hours set by the manufacturer has elapsed;
d) elements that avoid direct glare and reflection, as well as the strobe
effect, and
The pre-ignition or heating elements.

Study Report
A report containing the information collected in the survey, the documents
supplementing it and the data obtained during the evaluation must be
developed and maintained with at least the following information:
A. The descriptive report of the normal operating conditions, in which the

evaluation of the lighting levels was carried out, including the descriptions of
the process, facilities, jobs and the number of workers exposed by area and
position of work;
B. The distribution of the evaluated area, indicating the location of the

measuring points;
C. The results of the evaluation of lighting levels indicating their uncertainty;

Surveillance
Surveillance in compliance with this standard is the secretariat of Labour
and Social welfare.
Methods to evaluate the levels of
illumination
The content of this guide is a complement to the best understanding of the standard and is not mandatory.
Method IES
It is used to evaluate the average lighting level in the work area, based on the geometry of the area and the layout of the luminaires, when:
•
The area is regular and the luminaires are symmetrically spaced in two or more rows.
•
The area is regular with a symmetrically-positioned luminaire.
•
The area is regular with a row of luminaires.
•
The area is regular with one or more continuous lamps.
•
The area is regular with a row of continuous luminaires.
•
The area is regular with a luminous roof.
With this method, the measurements are taken in a few points of the workplace considered representative of the measurements that could
be carried out in other points of equal condition, based on the regularity of the area of the place and the symmetry in the distribution of the
Luminaires.
illumination
Room Constant Method
It is used to evaluate the average lighting level in the workplace from a certain
number of measurements and measuring points depending on the room constant,
K, which is given by where L is the length of the room, to the width and h the height
of the luminaires on The useful plane.
illumination
Determination of the average illumination (Ep):
When measurements are made for the purpose of verifying the values for a new installation, the
necessary precautions should be taken to ensure that the evaluations are carried out under
appropriate conditions (nominal supply voltage, Ambient temperature, choice of lamps, etc.) or
for the illumination meter readings to be corrected taking into account these conditions.
The calculation of the average level of illumination for the room constant method is done with the
following expression:
Ep = 1/N (ΣEi)
Where:
Ep = Average level in lux.
Ei = Illumination level measured in lux at each point.
N = number of measurements made.

Bibliography
• 16.1 Ley Federal sobre Metrología y Normalización, publicada en el Diario Oficial de la Federación el 1 de julio de 1992, México.
16.2 Reglamento Federal de Seguridad, Higiene y Medio Ambiente de Trabajo, publicado en el Diario Oficial de la Federación del 21 de enero de
1997, México.
16.3 Conocimientos Básicos de Higiene y Seguridad en el Trabajo, Ruiz Iturregui, José Ma., Editorial Deusto, 1978, Madrid, España.
16.4 Encyclopedia of Occupational Health and Safety, International Labour Office, Geneva. Third Edition 1983, Fourth Impresion, 1991.
16.5 Física General, Zemanski, Mark W., Sears, Francis W. Editorial Aguilar, 1966, México.
16.6 Guide on Interior Lighting, 2o. Edition, International Commission on Illumination. CIE 29.2 86, 1998, Vienna, Austria.
16.7 I.E.S. Lighting Handbook. 1995, Illuminating Engineering, Society, USA.
16.8 Iluminación Interna, Vittorio Re. Editorial MARCOMBO, S.A., 1979, Barcelona, España.
16.9 Luminotecnia, Enciclopedia CEAC de Electricidad. Dr. Ramírez V., José, Editorial CEAC, S.A., 1972, México.
16.10 Manual de Ingeniería, Perry, J.H.; Perry, R.H. Editorial Labor, S.A., 1966, Madrid, España.
16.11 Manual del Alumbrado, Westinghouse. Editorial Dossat, S.A., 1985, Madrid, España.
16.12 Principios de Iluminación y Niveles de Iluminación en México. Sociedad Mexicana de Ingeniería e Iluminación, Asociación Civil. Revista
Ingeniería de Iluminación, mayo-junio 1967, México.
16.13 The Industrial Environment. Its Evaluation & Control. U.S. Department of Health, Education, and Welfare Public Health Service; Center for
Disease Control; National Institute for Occupational Safety and Health, 1973, USA.
16.14 Iluminación interna, el instalador cualificado, Vottirio Re, Editorial Marcobo, Boixareu Editores 1979, Barcelona, España.
16.15 Técnicas de iluminación en fotografía y cinematografía, Bernal Francisco, Omega, 2003 Barcelona.

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NOM-025-STPS-2008

CONDITIONS OF LIGHTING IN THE

4.1. Work area:

4.2. Labour authority, Labour authority:

4.5. Critical Lighting Condition:

4.7. Complementary lighting:

4.9. Illumination; Illuminance:

4.10. Localized illumination:

4.11. Luminaire; Fixture:

4.13. Lighting Level:

4.14. Working plane:

4.15. Focal points of the luminaires:

4.14. Lighting system:

4.15. Visual task:

(a) Avoid direct glare or reflection on the worker;

(b) To select a visual background suitable for workers ' activities;

D) Avoid areas where there are sudden changes in lighting.

b) The ventilation of the luminaires;

c) The replacement of the luminaires when they cease to function, or after

The pre-ignition or heating elements.

A. The descriptive report of the normal operating conditions, in which the

B. The distribution of the evaluated area, indicating the location of the

C. The results of the evaluation of lighting levels indicating their uncertainty;

Ep = Average level in lux.

Ei = Illumination level measured in lux at each point.

N = number of measurements made.

16.7 I.E.S. Lighting Handbook. 1995, Illuminating Engineering, Society, USA.

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