Thousands of people die every year in developing countries due to electrical accidents. Fire has destroyed property worth millions of dollars. Data reveals that 42% of fires in buildings are due to electrical short circuits, and approximately 5000 deaths are due to electrical reasons. The majority of electrical accidents, such as fire, happen in low-voltage systems.
The main reasons for electrical accidents are poor design and quality of electrical installations, maintenance, workmanship issues, and old installations.
Bureau of Indian Standards (BIS) through its Electrical Installations Sectional Committee (ETD 20) under ETDC is responsible for the preparation of Indian Standards for safety and related matters in the designing, erection, and maintenance of electrical installations from the point of view of safety and good engineering practices.
BIS has recently revised the National Electrical Code of India, which was released on January 6, 2023, by Shri Piyush Goyal, Hon’ble Minister of Commerce & Industry, Consumer Affairs, Food & Public Distribution, and Textiles.
This code was first formulated in the year 1985 and was subsequently revised in 2011. In this version, BIS has comprehensively revised the National Electrical Code and brought out a state-of-the-art and most contemporary version of the NEC in line with the latest international practises.
The National Electrical Code of India (NEC) is an all-inclusive Electrical Installations Code prepared by BIS, providing guidelines for regulating electrical installation practises across the country.
The code contains:
Good practices for the selection of electrical equipment forming part of an electrical installation;
Recommendations concerning safety in the wiring of electrical installations,
General safety procedures and practices in electrical work; and
Additional precautions must be taken when using electrical equipment in hazardous environments such as an explosive or active atmosphere.
As the preeminent electrical code in the country, it establishes the basics of electrical safety.
The code contains 8 Parts and 49 sections.
General and Common Aspects ( 22 Sections )
Electrical installations in stand by generating stations and captive substations (2 Sections)
Requirements for special installations or locations ( 22 Sections )
Electrical installations in industrial buildings
Outdoor installations ( 3 Sections )
Electrical installations in agricultural premises
Electrical installations in Hazardous area
Solar Photovoltaic (PV) power supply systems
This code provides detailed protection measures for a) Protection against Electric Shock
b) Protection Against Thermal Effects
c) Protection Against Overcurrent and Short-circuit Current
d) Protection Against Voltage Disturbances
e) Design, Selection, Erection and Verification of an electrical installation
a) Part 1 largely covers general and common aspects of electrical installation, highlights the need to handle electrical works in accordance with relevant guidelines right from concept stage to completion and post completion maintenance. Part 1 comprises of 22 sections.
In the initial sections 1 to 8 of Part 1 scope of the NEC, exclusions, definitions of fundamental terms, guidelines in respect of the preparation of drawings, diagrams, charts, units of measurement, standard values, fundamental design principles, and general characteristics are covered.
Part 1/Section 9 closely associated with electricity and its human interface through wiring installations. This section highlights the need of coordination between works of architect, civil construction, other building services from the perspective of requirements of electrical installation.
Part 1/Section 10 to 13 explains about protective measures from electric shock, fire, over current, over voltage and section 17 explains about verification.
Part 1/Section 18 covers general requirements associated with earthing in electrical installation. Latest provisions from IS 3043 and IS 732 have been included in this section. Different earthing systems, with diagrams are explained in this chapter.
Part 1/Section 19 covers lightning protection , damages due to lightning and need of lightning protection based on risk assessment, selection & design of Lightning protection system.
Part 1/Section 20 speaks about power quality, pinpoints the causes, and its effects at user end and the supply system. Under the scenario of increasing use of systems and appliances with nonlinear loads, this section is very important.
Part 1/Section 21 covers aspects of energy efficient design, selection of equipment and the need of energy audit to optimize energy use. Concept of Load Energy Profile and setting up power monitoring devices from this section, will be useful for the designers to achieve the goal of energy efficiency.
b) Part 2 of the National Electrical Code of India covers the requirements relating to electrical design, selection, along with installation, testing, commissioning and maintenance of stand-by generating stations and captive substations.
Standby generating sets are generally the standby power supply source and play an important role in preserving property and lives in emergencies.
Reference of Central Pollution Control Board (CPCB) guidelines and Petroleum and Safety Explosives Guidelines have also been included here.
c) Part 3 of the NEC covers the requirements for electrical installations in special locations where safety measures in addition to the recommendations in Part 1 are necessary.
Special locations which are in common use are : Community halls and offices, Office buildings, shopping and commercial centres and institutions, Hospitals, Hotels, Electrical installations in multi-storeyed buildings etc .
For example, Part 3 of Section 9 explains about medical locations, which are areas where patients are being treated and where metallic objects or conductive fluids are bypassing the skin. The chance of shock for the patient under treatment is much higher in these locations; hence, additional shock reduction measures. Medical facilities are in an oxygen-rich environment. This needs special measures against the ignition of fire as well.
a) Part 4 of the NEC covers the electrical installations in industrial buildings. This part comprehensively classifies the types of industrial buildings based on fire safety, power consumption, and pollution level and suggests guidelines for the design and construction of electrical installations.
b) Part 5 of the NEC covers Outdoor installations. Outdoor installations are distinct in nature as being exposed to moderate to heavy environmental conditions like rain water, heavy formation of dust, seasonal conditions , ambient temperature. It comprises of three main sections 1) Public Lighting installation 2) Temporary outdoor installations and 3) Permanent outdoor installation. The duration for which an installation is erected determines whether it is permanent or temporary; duration of less than six months is designated as temporary installation.
c) Part 6 of the NEC covers electrical installations in agricultural premises to ensure safety against electrical faults. This part covers requirements for external influences like the presence of water, foreign solid bodies, corrosive or polluting substances, flora and fauna, etc., which are common at these locations.
d) Part 7 of the NEC covers installations in hazardous areas such as petroleum refineries, petrochemicals and chemical industries. To determine the type of electrical installation appropriate to a particular situation, the hazardous area have been divided into three zones, namely, Zone 0, 1 and 2 according to the degree of probability of the presence of hazardous atmosphere.
e) Part 8 of the NEC covers comprehensive guidelines specific for Solar PV installation including Modules, Strings & Array, inverter, controller and balance of system giving details of design, installation safety and quality requirements of PV installations suitable for Indian conditions. Solar installation has lots of dc system in which general protective system adopted for ac system may not directly work. Special measures are necessary for fault protection and shock protectionve measures are mentioned in the code.
This code is expected to be extensively used by: government and private construction agencies in electrical installations; building professionals like architects; electrical engineers and consultants; electrical equipment manufacturers and suppliers; research institutions for their research purposes; and faculty and students of academic institutions for imparting technical education.
It may be concluded that in all electrical works, it is very necessary that certain elementary safety practices are observed. It may be noted that the rules and regulations in India are similar to those in other developed or developing nations. Still, the accident rates are higher in comparison to other developed or developing nations. It has been found that quite a large number of accidents occur due to the neglect of these practices.
These accidents may be avoided if the electrical engineers design the electric installation taking into account the requirements mentioned in the National Electrical Code of India, using the right protection devices for the right equipment, and if electricians and other professionals carry out proper verification (initial and periodic) in accordance with the criteria given in the NEC in adherence to the safety regulations.