[PDF]SP 30: National Electrical Code 2011

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SP 30 (2011): National Electrical Code 2011 [ETD 20:
Electrical Installation]



Satyanarayan Gangaram Pitroda
Invent a New India Using Knowledge




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Bhartrhari — Nltisatakam
"Knowledge is such a treasure which cannot be stolen"





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NATIONAL ELECTRICAL CODE 2011
( First Revision )




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BUREAU OF INDIAN STANDARDS



SP30:2011



FIRST PUBLISHED AUGUST 1985
FIRST REVISION FEBRUARY 201 1

© BUREAU OF INDIAN STANDARDS

ICS 01.120; 91.160.01

PRICE Rs. 4070.00



PUBLISHED BY BUREAU OF INDIAN STANDARDS, MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR
MARG, NEW DELHI 1 10 002, PRINTED BY THE GENERAL MANAGER, GOVT. OF INDIA PRESS, NASIK



INTRODUCTION



India is on the path of development and its infrastructure sector has grown progressively. The buildings and
services so constructed depend on power for their construction and effective utilization. In fact, power is one of
the prime movers of development and electrical energy is the predominant form of energy being used due to ease
of generation/conversion, transmission, and final utilization.

Specific regulations to be adhered to in the supply and use of electrical energy had been laid down by the Indian
Electricity Act, 1910 and the Indian Electricity Rules, 1956 framed thereunder. However, a need was felt to
elaborate upon these regulations since the agencies involved have varied practices in view of their diverse interests
and different accessibility levels to technological developments. In order to rationalize these practices, India's
first National Electrical Code, formulated in 1985, was a compendium of several well established codes of practice
which provided assistance on economic selection, installation and maintenance of electrical equipment employed
in the usage of electrical energy. The code complemented and elaborated on the Indian Electricity Rules, 1956
for the ease of application by the system engineers by recommending the best practices for electrical installations
in a consolidated form in order to provide for unified practices and procedures along with consideration for
safety and economic usage of energy in the design, execution, inspection and maintenance of electrical installations
of various locations.

During the formulation of the National Electrical Code in 1985, it was realized that the referred codes, for
example, those on wiring practice, earthing, lightning protection etc need to be revised in line with the practice
and technology available at that time. It had also been planned that after the relevant codes are revised, the
National Electrical Code would also need to be revised. After the publication of NEC 1985, the referred Codes
were revised. However, the task of revision of NEC could not be taken up in earnest immediately after the
revision of various codes of practice. Over the years, there have been yet more changes in the technology; new
practices have evolved and got modified. There have been tremendous socio-economic changes, and corresponding
change in the pattern of the usage of electricity. Electricity Act 2003 has been notified and power sector reforms
have been firmly established. During the Ninth Plan, it was realized that it is necessary to have an Energy
Conservation Act. Accordingly, the Government has enacted the Energy Conservation Act, 2001 to meet the legal
requirement needed to enforce energy efficiency and conservation measures. Due to all such changes, the present
scenario is at great variance with that of 1985, when the Code was first formulated. Therefore, an urgent need was
felt to revise the NEC at the earliest to maintain its relevance in the present context.

The task for revision of NEC was taken up by the Electrical Installations Sectional Committee, ETD 20 considering
the above factors. This revision follows the earlier structure of NEC, with modifications and additions being
incorporated in line with IEC 60364 series on 'Electrical Installations' as well as the changes and developments
that took place since the publication of NEC 1985. It is visualized that in future, further harmonization with
international codes may be considered.

Electrical installation should be carried out in accordance with the Indian Electricity Rules, 1956 and relevant
regulations as amended or brought into force from time to time. All material, accessories, appliances etc., used in
an electrical installation should conform to Indian Standards wherever they exist. There should be good
workmanship and proper coordination and collaboration between the architect, building engineer and the electrical
engineer from the planning stage itself. The design of electrical installation is required to take into account the
characteristics of available supply, nature of demand, environmental conditions, type of wiring and methods of
installations, protective equipment, emergency control, disconnecting devices, preventing of mutual influence
between electrical and non electrical installations, accessibility etc.

The Code is divided into eight parts, which are further divided into sections. Part 1 covers the General and
common aspects, which would apply to all types of electrical installations. Wiring installations are an important

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aspect of any electrical installation. These have been revised to align with international practice and it is proposed
to revise the relevant code of practice for wiring installations also. The Sections related to Earthing and Lightning
protection have been modified and corresponding modification is also being initiated to respective codes. Aspect
of voltage surges has also been included. Energy conservation aspects had been emphasized in NEC 1985.
Meanwhile, Energy Conservation Act, 2001 has been notified. Therefore, energy conservation aspects have been
further elaborated and energy audit has also been included.

This Code excludes the requirements coming under the purview of utilities, namely, the large generating stations,
distribution substations and associated transmission system, or captive generator sets of very large capacity. It
covers the requirements relating to standby or emergency generating stations and captive substations intended
for serving an individual occupancy and intended to serve a building or a group of buildings normally housed in
and around it. It gives guidelines on layout and building construction aspects, selection of equipment, transformer
installations, switching stations and station auxiliaries. Reference to pollution norms as laid down in Environment
Protection Act 1986 for diesel generator sets has now been included.

Non-industrial buildings include domestic dwellings, office buildings, shopping and commercial centers and
institutions, recreational & assembly buildings, medical establishments, hotels and sports buildings etc. Optimum
benefits from the use of electricity can be obtained only if the installation is of sufficient capacity and affords
enough flexibility. Safety, economy, efficiency, reliability, convenience as well as provision for future expansion
are major considerations in planning the electrical layout. Guidelines are provided based on general characteristics
of installations, supply characteristics and parameters. S witchgear for control and protection, service lines, metering,
earthing, building services, fire protection and miscellaneous provisions have been covered. Miscellaneous
provisions include telephone wiring, call bell system, clock system, group control, audio visual systems, closed
circuit TV where applicable, emergency lights for critical areas of the dwelling. Provision of increased number of
points for residential units in order to accommodate the gadgets available and to avoid overloading of points by
consumer and reference to miniature circuit breakers in addition to fuses under requirement of switchgear for
control and protection has been made.

Electrical networks in industrial buildings serve the purpose of distributing the required power to the consuming
points where it is used for a multitude of purposes in the industry. The design of electrical installation in industrial
premises is therefore more complicated than those in non-industrial buildings. Industrial installation has to take
care of load requirements and supply limitations in a simple and economic manner, ensuring at the same time full
protection to human life and loss of property by fire. The network layout should also facilitate easy maintenance
and fault localization. A particular feature of electrical installations in industrial buildings is the reliability of
supply to essential operations for which standby and emergency supply sources/networks are available. The
needs of such systems would depend on the type and nature of the industrial works.

Locations in industrial buildings which are by their nature hazardous, require special treatment in respect of
design of electrical installations therein. Industrial installations have been classified depending on the specified
criteria therein in order to help identify the specific nature of each industry and the locations therein, for assisting
the design engineer in the choice of equipment and methods.

Electrical installations are often required to be designed and erected for use for short periods of time ranging
from a few hours to few months and are connected to the supply source in open ground. Such installations are
generally unprotected from environmental hazards as compared to installations in buildings. Major risks in the
use of power in such installation arise from short circuit resulting in fire accidents and exposure to live wire
resulting in shock. Outdoor installations are required to comply not only with the general requirements, but also
additional requirements regarding supply intake arrangements, control of circuits, earthing, and protection against
overload, short circuit and earth leakage.

There is increased use of electricity for essential purposes in agriculture with the increase in sophistication in
organising the farm output of the country. Installations in agricultural premises are different as the external
influences on the electrical services are quite different from those encountered elsewhere. Even though the overall
power requirements for such installations could be small, the presence of livestock and other extraneous factors
necessitate laying down specific requirements to ensure safety. Specific requirements of electrical installations in
agricultural premises which include premises where livestock are present and farm produce are handled or stored
have been covered. Agricultural processing at the farm premises has now been included.

Any area, where during normal operations a hazardous atmosphere is likely to occur in sufficient quantity to
constitute a hazard had to be treated in a special manner from the point of the design of electrical installation.

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Many liquids, gases and vapours which in industry are generated, processed, handled and stored are combustible.
When ignited these may burn readily and with considerable explosive force when mixed with air in the appropriate
proportions. With regard to electrical installations, essential ignition sources include arcs, sparks or hot surfaces
produced either in normal operation or under specified fault conditions. NEC provides guidelines for electrical
installations and equipment in locations where a hazardous atmosphere is likely to be present with a view to
maximizing electrical safety. When electrical equipment is to be installed in or near a hazardous area, effort is to
be made to locate much of the equipment in less hazardous or non-hazardous areas and thus reduce the amount
of special equipment required. Hazardous areas can be limited in extent by construction measures, that is, walls
or dams. Ventilation or application of protective gas also reduces the probability of the presence of explosive gas
atmosphere so that areas of greater hazard can be transformed to areas of lesser hazard or to non-hazardous areas.
A number of product standards offering different types of protection are available. Regulatory requirements are
to be adhered to for such installations. Standards pertaining to classification of hazardous areas having flammable
gases and vapours for electrical installation and guide for selection of electrical equipment for hazardous area
have been revised and the changes have been incorporated in the NEC.

Excessive reliance on fossil fuel resources to meet the energy requirement of the country is considered unsustainable
in the long-run and has an adverse impact on the environment and ecology. This has resulted in the quest of
renewable sources of energy as a viable option to achieve the goal of sustainable development. Harnessing of
solar energy is one such area which is expected to supplement energy supply efforts. Hence a new part on solar
photovoltaic installations has been added.

The Code excludes guidance on tariff. Product details are also excluded from the Code as separate product
standards are available for these. When these standards are revised subsequent to the revision of NEC, there
could be instances where the latest Codes differ from the revised NEC. It is therefore recommended to follow the
provisions of the latest standards/codes of practice. In order to avoid instances where the Indian Standards and
provisions of this Code differ, attention has been drawn to the relevant standard. However, for certain provisions
in this Code, the relevant requirements from corresponding Indian Standards have been extracted and reproduced.
In all cases, for detailed guidance, reference should be made to the individual standard and should any contradiction
be observed between the provisions in individual standard and those reproduced herein, the provisions of the
former shall be considered accurate. As a general rule, technological innovations such as better materials or new
and better method also proved as 'good practice' would first be introduced in the individual standard as appropriate
than in the National Electrical Code. In order to keep pace with such changes and to incorporate the additional
knowledge that will be gained through the implementation of the Code, a continuous review is envisaged. Thus,
the users of this Code are encouraged to bring to the notice of Bureau of Indian Standards, need of modifications
that may be required in the light of changes in technology or other factors, as this is a continuous process.

The National Electrical Code (hereafter referred to as the Code) is intended to be advisory. It contains guidelines,
which can be immediately adopted for use by the various interests concerned. Its provisions are presently not
mandatory but are expected to serve as a model for adoption in the interest of safety and economy and with the
intent to keep our electrical installation practices at par with the best practices in the world.



COMMITTEE COMPOSITION

Electrical Installations Sectional Committee, ETD 20

Chairman

SHRI N. NAGARAJAN

Chief Engineer

Central Public Works Department, New Delhi



Organization
Areva Transmission and Distribution, Noida
BEST Undertaking, Mumbai

BSES Rajdhani Power Ltd, New Delhi
Central Electricity Authority, New Delhi

Chief Electrical Inspectorate (Kerala), Thiruvananthapuram

Chief Electrical Inspectorate (Madhya Pradesh), Bhopal

Chief Electrical Inspectorate (Orissa), Behrampur

Chief Electrical Inspectorate (Tamil Nadu), Chennai

Chief Electrical Inspectorate (Uttranchal), Nainital

Central Public Works Department, New Delhi

Development Consultant Limited, Kolkata



Representative(s)

Shri Biswajit Saha

Shri S. A. Puranik

Shri P. R. B. Nair (Alternate)

Shri Shantanu Dastidar

Shri R. K. Verma

Shri B. R. Singh (Alternate)

Shri K. S. Beena

Shri K. K. Unni (Alternate)

Shri S. S. Muialde

Shri A. K. Dubey (Alternate)

Shri G. C. Choudhury

Shri S. H. Rahman (Alternate)

Shri R. Subramaniyan

Shri S. Appavoo (Alternate)

Shri Anupam Kumar
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