NATIONAL BUILDING CODE OF INDIA -2016
Part 8 Building Services
(Section-2 Electrical & Allied Installations)
What is National Building Code (NBC) & what is role of NBC here?
The full form of NBC is National Building Code of India. It is a national instrument providing guidelines regulating the building construction activities which includes electrical work, air conditioning & ventilation, fire & life safety work etc across India. It is applicable for all agencies/departments involved in construction activities such as Public Works Department, Govt construction departments, local bodies or private construction agencies. NBC updated its guidelines in 2016 which is applicable till date.
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SCOPE:
This code (Part-8/Section 2) covers the essential requirements for electrical installations in buildings to ensure efficient use of electricity including safety from fire & shock. This section also includes general requirements relating to lightning protection of buildings & brief provisions on certain allied installations.
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GENERAL RQUIREMENTS:
3.1 – Conformity with The Electricity Act, 2003 & Central Electricity Authority (measures relating to the safety & electrical supply) Regulations, 2010 a amended up to date.
The installation shall generally be carried out in conformity with above two guidelines & also the relevant regulation s of the electrical supply authority concerned from time to time.
3.2 – Material –
All materials, fittings, appliances etc used in electrical & allied installations shall confirm to the Part 5 ‘Building Materials’ of the code & other concerned Indian Standards.
3.3 – Coordination with electrical supply authority –
- a) In all cases, that is, whether the proposed electrical work is a new installation or extension of an existing one or a modification involving major changes, the electricity supply undertaking shall be consulted about the feasibility etc at an early date.
The wattage per square meter & permissible diversity consideration shall be defined as per the type of building (residential, commercial, mercantile, industrial, retail, convention, exhibition, hotel, hospitals, institution, flatted factory, group housing etc).
The wattage per square feet shall be defined considering probable loads as per city grading such that future loading into the development is accounted.
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b) Addition to an installation –
An addition, temporary or permanent, shall not be made to authorized to an existing installation until it has been definitely ascertained that the current carrying capacity & condition of existing accessories, conductors, switches, rating of protective devices, power factor etc. affected, including those of supply authority are adequate for the increased load.
Load assessment & application of suitable diversity factor to estimate the full load current shall be made as a first step. This should be done for every circuit, submain & feeder.
Power factor, harmonics & efficiency of loads shall also be considered.
Diversity factor assumed shall be based on experience or as per table under 4.2.2.2.
Allowances should be made for about 15-20%for extension in near future.
The wiring system should be adopted taking into account environmental requirements hazards, if any in the building. The size of wiring cables are decided to carry load currents, to withstand thermal effects, due to overcurrent, short circuit & to ensure acceptance level of voltage drop.
3.4 – Power factor improvement in Consumer’s installation –
3.4.1 – Conditions of supply of electricity boards or licenses stipulate the lower limit of pf (power factor) which is generally 0.90 or better.
3.4.2 – Principles of causes of low pf are many. For guidance to the consumers of electric energy who take supply at low and medium voltages for improvement of power factor, reference shall be made to good practice (8-2(7)).
3.5 – Execution of work-
The work of electrical installations shall be carried out by a licensed electrical contractor and under the direct supervision of a person holding a certificate of competency and by persons holding a valid permit issued & recognized by any state govt.
3.6 – Safety procedures & practices shall be kept in view during execution of the work in accordance with good practices (8-2(8)).
3.7 – Safety provisions given in Part 4 ‘ Fire & Life Safety’ of the code shall be followed.
NBC guidelines are given in different sections which are given below. Each section has many sub sections whose detail is given in separately –
4. Planning of electrical installations
5. Distribution of supply & cabling
6. Wiring