unit 4

P M COLLEGE OF ENGINEERING Approved by AICTE, Ministry of HRD, Govt. of India,

Affiliated to Deenbandhu Chhotu Ram University of Science & Technology KAMI ROAD, SONEPAT, Haryana

E-mail: [email protected]; Website: www.pmkami.com

Managed By: Puran Murti Educational Society

Updated on: 26th Aug’14

UNIT4 (ELECTRICAL ASPECTS OF BUILDING SERVICES)

22(A) GENERAL GUIDELINES Extensive guidelines on building design aspects have been covered in SP 7 from the point of view of ensuring economic services in an occupancy. These shall be referred to from the point of view of ensuring good design of building services and early coordination amongst all concerned. Orientation of Building The chief aim of orientation of buildings is to provide physically and psychologically comfortable living inside the buildings by creating conditions which suitably and successfully ward off the undesirable effects of severe weather to a considerable extent by judicious use of the recommendations and knowledge of climatic factors. From the point of view of lighting and ventilation, the following climatic factors influence the optimum orientation of the buildings:

a) Solar radiation and temperature, b) Clouds, c) Relative humidity, and d) Prevailing winds.

22(B) ASPECTS OF LIGHTING SERVICES Principles of Good Lighting Good lighting is necessary for all buildings and has three primary aims. The first is to promote the work and other activities carried on within the buildings; the second is to promote the safety of people using the building; and the third is to create, in conjunction with the structure and decoration, a pleasing environment conducive to interest and a sense of well-being. Realization of these aims involves:

a) Careful planning of the brightness and colour patterns within the working area and the sur roundings so tha t attention is drawn naturally to the important areas, detail is seen quickly and accurately and the room is free from any sense of gloom or monotony.

b) Using directional lighting, where appropriate, to assist preception of task detail and to






give good modelling.

c) Controlling direct and reflected glare from light sources to eliminate visual

discomfort, d) In artificial lighting installations, minimizing flicker from certain types of lamp and

paying attention to the colour rendering properties of the light. e) Correlating lighting throughout the building to prevent excessive differences between

adjacent areas and so as to reduce the risk of accidents, and f) Installing emergency lighting systems where necessary. Good lighting design shall take into account the following:

a) Planning the brightness pattern from the point of view of visual performance, safety

and amenity and surroundings; b) For m of texture in the task area and surroundings; c) Controlling glare, stroboscopic effect and flicker; d) Colour rendering; e) Lighting for movement; f) Provision for emergency; g) Maintenance factors in lighting installation;

and h) Maximum energy effectiveness of the lighting system used consistent with the specific

needs of visual tasks performed. Design Aspect

Illumination Levels

The level of illumination for a particular occupation depends on the following criteria:

a) Adequacy for preventing both strain in seeing and liability to accidents caused by poor

visibility, b) Adequacy for realizing maximum visual capacity, c) Adequacy for the performance of visual tasks at satisfactory high levels of efficiency,

and d) Adequacy for pleasantness or amenity.

22(C ) ASPECTS OF VENTILATION Ventilation of buildings is required to supply fresh air for respiration of occupants, to dilute






inside air to prevent vitiation by body odours and to remove any products of combustion or other contaminants in air and to provide such thermal environments as will assist the maintenance of heat balance of the body in order to prevent discomfort and injury to health of the occupants. The following govern design considerations:

a) Supply of fresh air for respiration, b) Removal of combustion products or other contaminants and to prevent vitiation by

body odours, c) Recommended schedule of values of air changes for various occupancies, and d) The limits of comfort and heat tolerance of the occupants.

Methods of Ventilation General ventilation involves providing a building with relatively large quantities of outside air in order to improve general environment of building. This may be achieved in one of the following ways:

a) Natural supply and natural exhaust of air, b) Natural supply and mechanical exhaust of air, c) Mechanical supply and natural exhaust of air, d) Mechanical supply and mechanical exhaust of air.






23 ASPECTS OF AIR-CONDITIONING AND HEATING SERVICES The object of air-conditioning facilities in buildings shall be to provide conditions under which people can live in comfort, work safely and efficiently. It shall aim at controlling and optimizing factors in the building like air purity, air movement, dry bulb temperature, relative humidity, noise and vibration, energy efficiency and fire safety. The design of the system and its associated controls should take into account the following:

a) The nature of the application, b) The type of construction of building, c) External and internal load patterns, d) Desired space conditions, e) Permissible control limits, f) Control methods for minimizing use of primary energy, g) Opportunities for heat recovery,

h) Economic factors (including probable future cost and availability of power), i) Outdoor air quality, j) Energy efficiency,

k) Filteration standard, l) Hours of use, m) Outdoor air quality, and n) Diversity factor.

The operation of the system in the following circumstances should be considered when assessing the complete design:

a) In summer; b) In monsoon; c) In winter; d) In intermediate seasons;

e) At night; f) At weekends and holidays; g) Under frost conditions, where applicable; h) If electricity supply failure occurs and when the supply is restored; and i) If extended low voltage conditions persist.

Consideration should be given to changes in building load and the system design so that maximum operational efficiency is maintained under part load conditions. Similarly, the total system should be separated into smaller increments having similar load requirements so that each area can be separately controlled to maintain optimum operating conditions.






24(A) ELECTRICAL ASPECTS OF LIFTS AND ESCALATOR SERVICES For the information of the electrical engineer, the lift/escalator manufacturer should advise the architect/engineer of the building of his structural and electrical requirements. This should be available early in the planning stage to ensure proper electrical provisions to be made for the service and suitable cables and switchgears. During preliminary planning of the building, the aspect of lifts and escalators installation shall be discussed with all concerned parties namely, client, architect, consulting engineer and/or lift manufacturer. The following aspects shall be taken into account to decide the electrical requirements for lifts:

a) Number of lifts, size, capacity and position; b) Number of floors served by the lift; c) Height between floor levels; d) Provisions for machine room and proper access to it; e) Provisions for ventilation and lighting; f) Electric supply required; g) Details of wiring and apparatus required; h) Quantity/quality of service; i) Occupant load factors; j) Car speed; k) Control system; l) Operation and maintenance;

m) Provision for lift and depth; n) Number of entrances; o) Provision of telephone or alarm bell inside the lift car; p) Provision of battery backup emergency light inside the lift car; and q) Providing battery backup automatic rescue device or uninterrupted power supply

(UPS).

24(B) ELECTRICAL ASPECTS OF FIRE ALARM AND FIGHTING SYSTEMS

This clause covers the electrical aspects of the installation of fire alarm/protection system in buildings.

This clause is applicable in general to all types of occupancies, while specific requirements if any or individual situations are covered in the respective sections of the Code.

For total requirements for fire protection of buildings, including non-electrical aspects such






as choice and disposition of fire-fighting equipment, depending on the nature of occupancy installation and maintenance aspects, etc., reference shall be made to SP 7 and the relevant Indian Standards.

Fire Detectors The following types of fire detectors are available for installation in buildings:

a) Heat detectors 1) ‘Point’ or ‘spot’ type detector 2) Line type detector.

b) Smoke detectors: 1) Optical detectors. 2) Ionization chamber detector, 3) Chemically sensitive detector. c) Flame detectors.

Wiring for Fire Alarm Systems The equipment and wiring of the fire alarm system shall be independent of any other equipment or wiring, and shall be spaced at least 5 cm away from each other and other wiring. The wiring of the fire alarm systems, shall be in metallic conduits. The wiring shall be kept away from lift shafts, stair cases and other flue-like opening. Alarm sounders shall be of the same kind in a particular installation. For large or intricate premises, it is necessary that the origin of a call be indicated. For this, the premises shall be divided into sections zones. All call points in a section shall be connected to the same indicator. The various drops or lamp indicators shall be grouped together on the main indicator board or control panel. When the premises are extensive, a number of main indicator boards may be used covering different sectors. These shall be supplemented by sector indicators for the various sectors at a central control point. At the control point the indicator board or the zone and section indicating boards and all common control apparatus and supervisory equipment shall be located. For every installation a control point shall be provided, where it can be under constant observation. The main control centre shall be located on the ground floor and should be segregated from the rest of the building by fire-break wall. No section shall have more than 200 fire detectors connected together. The origin of the calls may be indicated by the use of lamp indicators. Each indicator shall include:






a) Two lamps connected in parallel associated with each indication, so arranged that

failure of either of the lamps is readily apparent, or b) One lamp glowing during normal operation of the system for each section and the

alarm indicated by the extinguishing of the lamp for the section where the call originates. Alarms should not sound on the failur e of the indicator.

The arrangement of the circuits and the electrical connections shall be such that a call or fault in any circuit does not prevent the receipt of calls on any other circuit. The indicating device associated with the various call points and sections shall be grouped together on the main indicator board. If necessary remote indicating panel, with audible alarms in the night quarters of the caretaker of the building should be provided. The silencing switches/push buttons in their off position shall give an indication of this fact on the main control panel operation of silencing switches shall not prevent sounding of alarm fr om any other zone simultaneously, or cancel the other indications of the alarm or fault. For fire alarm systems, cables of the following types shall be used:

a) Mineral insulated aluminium sheathed cables; b) PVC insulated cables, c) Rubber insulated braided cables, d) PVC or rubber insulated armoured cables, and e) Hand metal sheathed cables.

The source of supply for the alarm system shall be a secondary battery continuously trickle/float charged from ac mains, with facilities for automatic recharging in 8 h sufficiently to supply the maximum alarm load at an adequate voltage for at least 2 h. The capacity of battery shall be such that it is capable of maintaining the maximum alarm load on the system at an adequate voltage for at least 1 h plus the standing load or losses for at least 48 h. Suitable overload protective devices shall be provided to prevent discharging of the batteries through the charging equipment. Fire Fighting Equipment Requirements for Electrical Drives for Pumps in Hydrant and Sprinkler Systems Full details of the electric supply shall be furnished together with details of generator plant to the appropriate authorities Sufficient power shall be made available for the purpose and the power source shall be entirely independent of all other equipment in the premises and shall not






be interrupted at any time by the main switch controlling supply to the premises. An indicator lamp shall continuously glow in a prominent position to indicate status of power in the substation and in the fire-pump room. Pumping sets shall be direct coupled type, and shall work satisfactorily at varying load. All motors and electrical equipment shall be continuously rated, drip-proof with air inlets and outlets protected with meshed wire panels where required motors shall have a suitable fixed warming resistance to maintain them in dry condition. The starting equipment of the set shall incorporate an ammeter and clearly marked to show full load current. They shall not incorporate no-volt trips. The electric circuit for fire fighting system shall be provided at its origin with a suitable switch for isolation, but overload and no-volt protection shall not be provided in the switch.






25(A) CLOCK SYSTEMS Design Considerations A schematic diagram is shown in Fig. The enclosure of the clocks shall have no openings giving access to live parts or functional insulated parts or functional insulation other than the openings necessary for the use and working of the clocks. Where such openings are necessary, sufficient protection against accidental contact with live parts shall be provided. To ensure necessary continuity of supply, direct connection of the system to the supply mains is not recommended. Batteries should always be provided. The capacity of the battery shall be at least sufficient to supply the installation for 48 h, not less than 10 Ah. Where the supply is ac, single battery on constant trickle charge is recommended, means being provided for charging at a higher rate when necessary. Where the supply is dc, two batteries should be provided with changeover switch.

FIG. A IMPULSE MASTER CLOCK SYSTEM






25(B) ELECTRICAL ASPECTS OF COMPUTER CONTROL OF ENVIRONMENTAL SYSTEMS Building Management System (BMS)

Thermal comfort, lighting, ventilation, air- conditioning, security, safety, fire detection and control system and electrical power are always required, and residential building represents this basic level of need.

The management of building services systems for a larger establishment is more difficult due to the variety, increased complexity, lack of individual responsibility and high capital and operating costs for the systems involved. The more complex control systems are termed building management systems (BMS). They are employed in commercial, public and industrial buildings and control the services of heating, ventilation, air-conditioning, steam, refrigeration, gas, water, general and emergency lighting, emergency electrical systems, power distribution, mechanical transportation, fire detection alarm and fighting systems, general and noxious fume ventilation, security and waste disposal.

The building management systems (BMS) means that all services can be monitored and reset from a central location without delay or movement by the engineer. BMS can also advise on preventative maintenance schedules, thereby improving overall plant reliability and operating efficiency. Consequently, plant operation is greatly simplified by allowing an engineer to reset any control level, monitor energy con- sumption, organize maintenance and make fault diagnosis from a central location. Remedial action is quicker and can often be carried out by a smaller engineering staff than would be required otherwise.

BMS Architecture

BMS architecture and performance requirements shall be based on a distributed system of intelligent, stand alone controllers, operating BMS incorporates control and monitoring of all systems such as environmental, fire and security but, in some cases, separate dedicated fire protection systems are favoured by the authorities and reference to local fire codes and regulations is essential. The integration of fire protection and security systems into BMS shall be subject to the approval of the local fire prevention authority. It is possible to keep the fire protection system panel separate while still providing communication links with the BMS for alarm and reporting purposes. Back-up power supplies such as the UPS systems, although required for any BMS, need more consideration for centralized intelligence systems. A parallel systems structure and duplication of equipment to provide redundancy facilities may also be necessary, depending on the level of reliability required or the importance of the functions.






25(C ) TELEPHONE SYSTEMS Telephone systems are classified as communications systems. Telephone communication through the public network is in most countries the responsibility of the Telecom administrations. These are systems, which must meet more stringent requirements for reliability of transmission. Electronic Private Automatic Branch Exchanges(EPABX) Electronic private branch exchanges are connected to the pub lic ex c hang es thr ough ex c hang e lines. Operationall y they form par t of the subscr iber equipment of the public telephone system. EPABX permit internal communication between the extensions of a system and external communication, for approved b ranch systems, over the ex change lines. Communication within the private branch system, normally, does not attract charges. Backbone Cabling Generally the inter-floor/inter-building backbone cabling is included in the scope of main building design. The backbone cabling should accommodate analog voice signal alone or analog and data signals simultaneously, as the case may be. It is the speed of data transmission and bandwidth, which matter most in the design of the communication backbone. Exchange of Information The exact requirement of the subscribers shall be assessed before drawing out the specification of the EPABX system. This means that information on number of subscribers in the building, distribution of the phones in the floors and other areas, nature of traffic etc are to be collected. The initial and final r equirements of the installations should be ascertained as accurately as possible by prior consultations. Plans shall show:

a) details of the installations proposed; b) the accommodation and location of the EPABX console, monitor, etc; and c) the ducts and cable routing required for wiring.

Design Requirements The basic ar chitecture and perf ormance requirements of the modern day communication system is microprocessor-based pulse code modulated (PCM)/ Time Division Multiplexing (TDM) technology.






The environmental conditions for the EPABX should preferably be controlled so that the room air temperature is maintained between 10 oC and 40 oC and r elat ive humidity betw een 50 percent and 95 percent. Integrated Services Digital Network (ISDN) is a common requirement now-a-days for commercial buildings since it is possible to handle simultaneous calls of different types namely voice, data and images transfer (Tele & Video conferencing) without any loss of data, at a minimum speed of 64 kBps, which can be increased further depending on requirement. EPABX system shall be capable of interfacing with other EPABX system through appropriate protocol. Hardware Requirement Electronic private automatic branch exchange In EPABX system the individual call stations are connected each by a twisted pair of wires to the automatic exchange (see Fig.4). This is also the ter mination f or the ex chang e lines and, wher e necessary. Power supply Depending on the size and type of installation, the telephone system requires for its operation a dc power supply of 24 V or 48 V, which is obtained from the power mains through a rectifier. The rectifiers, provided with closed-loop control and for small and medium sized systems, are accommodated in the exchange housing. For large systems rectifiers (controlled) are supplied in separate cabinets. Standby Batteries Standby batteries can be provided as an adjunct to the rectifier. These are necessary for important installations such as police stations, fire stations, etc, to cover possible main supply failures. Space Requirements The switching equipment for the telephone systems and small EPABX’s takes up little room. Apart from the telephones, only relatively small wall- mounted junction boxes or exchange units are required. The exchanges, furthermore, produce little or no noise, so that they can be accommodated in an office if desired. For large systems a separate room should be provided for the exchange equipment, and similarly for the answering panel. Space should be allowed in planning for additional cabinets or racks, exchange equipment platforms etc that may be necessitated by future enlargement of the systems. The size of the battery room depends






upon the type of power supply equipment used. Features There are various features available with the present day EPABX with introduction of concerned cards and features to be incor porated have to be decided depending on functional requirement. Some of the most common features included are Abbreviated Dialing, Recorded Announcement System, Last number redial, Executive override, multi-party confer ence, call forwarding, Direct Inward Dialing (DID), Automatic alarm make-up call, STD barring, group hunting, networking facility.

FIG. 4 EXAMPLE OF THE ARRANGEMENT OF A BASIC EPABX SYSTEM IN LARGE BUILDING






26 ELECTRICAL INSTALLATIONS IN DOMESTIC BUILDINGS

(A)CLASSIFICATION The electrical installations covered in this Section, are those in buildings intended for the following purposes: Domestic Dwellings/Residential Buildings These shall include buildings in which sleeping accommodation is provided for normal residential (domestic) purposes with cooking and dining facilities. Such buildings shall be further classified as follows:

a) One or two family dwellings — These shall inc lude any pr ivate d welling w hic h is occupied by members of a single family and has a total sleeping accommodation for not more than 20 persons.

b) Apartment houses (flats) — These shall include any building or structure in which living quarters are provided for three or more families, living independently of each other and with independent cooking facilities. For example apartment houses, mansions and chawls.

(B)GENERAL CHARACTERISTICS OF INSTALLATIONS General guidelines on the assessment of characteristics of installations in buildings are given in Part 1/Sec 8 of this Code. For the purposes of installations falling under the scope of this Section, the characteristics defined below specifically apply. 27(A) SUPPLY CHARACTERISTICS AND PARAMETERS

Exchange of Information

General aspects to be taken note of before designing the electrical installations are enumerated in Part 1/Section 7 of this Code. However, the following points shall be noted particularly in respect of domestic dwellings. Before starting wiring and installation of fittings and accessories, information should be exchanged between the owner of the building or architect or electrical contractor and the local supply authority in respect of tariffs applicable, types of apparatus that may be connected under each tariff, requirement of space for installing meters, switches, service lines, etc, and for total load requirement of lights, fans and power.






While planning an installation, consideration should be given to the anticipated increase in the use of electricity for lighting, general purpose socket- outlet, kitchen, heating, etc. It is essential that adequate provision should be made for all the services which may be required immediately and during the intended useful life of the building, for the householder may otherwise be tempted to carry out extension of the installation himself or to rely upon use of multiplug adaptors and long flexible cords, both of which are not recommended. A fundamentally safe installation may be rendered dangerous, if extended in this way. Electrical installation in a new building should normally begin immediately on the completion of the main structural building work. For conduit wiring system, the work should start before finishing work like plastering has begun. For surface wiring system, however, work should begin before final finishing work lik e w hite washing , painting, etc. Usuall y, no installation work should start until the building is reasonably weatherproof, but where electric wiring is to be concealed within the structures, the necessary conduits and ducts should be positioned after the shuttering is in place and before the concrete is poured, provision being made to protect conduits from damage. For this purpose, sufficient coordination shall be ensured amongst the concerned parties. Estimation of Load Requirements The extent and form of electrical installations in domestic dwellings is basically designed to cater to light and fan loads and for electrical appliances and gadgets. In estimating the current to be carried by any branch circuit unless the actual values are known, these shall be calculated based on the following recommended ratings: ‘Power’ sub-circuits shall be kept separate and distinct from ‘lighting-and fan’ sub-circuit. All wiring shall be done on the distribution system with main and branch distribution boards located at convenient physical and electrical load centres. All types of wiring, whether recessed or surface should be capable of easy inspection. The surface wiring when run along the walls should be as near the ceiling as possible. In all types of wirings due consideration shall be given for neatness and good appearance and safety.

Balancing of circuits in three-wire or polyphase installation shall be planned beforehand. In each case, it is recommended that all socket-outlets in a room are connected to one phase. The conductors shall be so enclosed in earthed metal or incombustible insulating material that it is not possible to have ready access to them. If the points between which a voltage exceeding250 V is present are 2 m or more apart, the covers or access doors shall be clearly marked to indicate the voltage present 27(B) SWITCHGEAR FOR CONTRO L AND PROTECTION Location






All main switches or miniature circuit-breakers shall be either of metal-clad enclosed pattern or of any insulated enclosed pattern which shall be fixed at close proximity to the point of entry of supply. Open type switch boards shall be placed only in dry situation and in well ventilated rooms. They shall not be placed in the vicinity of storage batteries and exposed to chemical fumes. Main switch boards shall be installed in rooms or cupboards having provision for locking so as to safeguard against operation by unauthorized persons. In a damp situation or where inflammable or explosive dust, vapour or gas is likely to be present, the switch boards shall be totally enclosed or made flame-proof as may be necessitated by the particular circumstances. Switch boards shall not be erected above gas stoves or sinks or within 2.5 m of any washing unit in the washing room. Switch boards, if unavoidably fixed in places likely to be exposed to weather, to drip, or to abnormal moist atmosphere, their outer casing shall be weatherproof and shall be provided with glands or bushings or adopted to receive screwed conduit according to the manner in which cables are run. PVC and double flanged bushes shall be fitted in the holes of the switches for entry and exit of wires. A switch board shall not be installed so that its bottom is within 1.25 m above the floor, unless the front of the switch board is completely enclosed by a door, or the switch board is located in a position to which only authorized persons have access. Where so required, the switch boards shall be recessed in the wall. The depth of recess provided at the back for connection and the space at the front between the switchgear mountings shall be adequate. Equipment’s w hich are on the front of a switchboard shall be so arranged that inadvertent personal contact with live parts is unlikely during the manipulation of switchgears, changing of fuses or similar operations. No mounting shall be mounted within 2.5 cm of any edge of the panel and no hole other than the holes by means of which the panel is fixed shall be drilled closer than 1.3 cm from any edge of the panel






28(A) SERVICE LINES

The relevant provisions of IS 8061 shall apply. (B) METERING It is recommended to have two distinct circuits, one for lights and fans and the other for high wattage (power) appliances particularly when the tariff is different for light and power. Energy meters shall be installed at such a place which is readily accessible to both the owner of the building and the authorized representatives of the supply authority. These should be installed at a height where it is convenient to note the meter reading, it should preferably not be installed at a height less than 1 m from the ground. The energymeters should either be provided with a protective covering, enclosing it completely, except the glass window through which the readings are noted or should be mounted inside a completely enclosed panel provided with a hinged or sliding doors with arrangement for locking it. The room/space where energy meters are installed shall be kept clear from any obstruction. Means for isolating the supply to the building shall be provided immediately after the energymeter. (C)EARTHING IN DOMESTIC INSTALLATIONS Plugs and Sockets All plugs and sockets shall be of three-pin type, one of the pins being connected to earth. Lighting Fittings If the bracket type lamp holders are of metallic construction, it is recommended that they should be ear thed . All pedestal lamp fittings of metallic construction shall be earthed. Fans and Regulators Bodies of all table fans, pedestal fans, exhaust fans, etc., shall be earthed by the use of three-pin plugs. The covers of the regulators, if of metallic construction shall be earthed by means of a separate earth wire. Domestic Electric Appliances Bodies of hot-plates, kettles, toasters, heaters, ovens and water boilers shall all be earthed by the use of three-pin plugs. However, if fixed wiring has been used, then a separate earth wire shall be used for earthing these appliances.






Bath Room The body of automatic electric water heaters shall be earthed by the use of a three-pin plug or by a separate earth wire, if fixed wiring has been done. All non- electrical metal work including the bath tub, metal pipes, sinks and tanks shall be bonded together and earthed. Radio Sets F rom the point of view of good reception it is recommended that radio sets should be earthed through an electrode different from that of the main earth system for other electrical appliances. However, if it is not possible to have separate earth electrode, radio sets may be earthed through the main earth system. Miscellaneous Apparatus Where appliances utilizing gas and electricity are in use, for example, gas-heated electricity-driven washing machines, the inlet end of the gas supply shall be either fitted with a strong insulating bush, substantial enough to stand a flash test of 3 500 V and so designed as to be difficult to detach, or, where it is desirable or necessary that metal work in proximity to electrical






26. ELECTRICAL INSTALLATIONS IN COMMERCIAL BUILDINGS

(C)CLASSIFICATION The electrical installations covered in this Section, are those in buildings intended for the following purposes:

a) Office Buildings/Business Buildings — These include buildings for the transaction of business, for the keeping of accounts and records and similar purposes, professional establishments, offices, banks, research establishments, data processing installations, etc.

b) Shopping/Commercial Centres/Mercantile Buildings — These include buildings used as shops, stores, market, for display and sale of merchandise, wholesale or retail, departmental stores, etc.

c) Educational Buildings — These include buildings used for schools, colleges and daycare purposes for more than 8 hours per w eek involving assembly of people for instruction and education (including incidental recreation), etc.

(D)GENERAL CHARACTERISTICS OF INSTALLATIONS General guidelines on the assessment of characteristics of installations in buildings are given in Part 1/Section 8 of this Code. For the purpose of installations falling under the scope of this Section the characteristics defined below generally apply.






27(C )SUPPLY CHARACTERISTICS AND PARAMETERS Exchange of Information Proper coordination shall be ensured between the architect, building contractor and the electrical engineer on the various aspects of installations design. From the point of view of the design of the va rious installations, the following shall be considered.

a) Maximum demand and diversity; b) Type of distribution system, mains and sub- mains; c) Nature of supply (current, frequency, nominal voltages

d) Prospective short-circuit current at the supply intake point; e) Division of the installation; f) Nature of the external influences g) Maintainability of the installations;

h) Nature and details of building services 1) Lighting, 2) Air-conditioning, and 3) Lifts

j) Other details as relevant such as, pumps for fire fighting, lighting, fire-alarm systems, telephones, call-bells, clock systems, etc;

k) Telephone circuits including extensions and intercom facilities; m) CCTV for information display and security; n) Computer installat ion facility where applicable; and p) Metering system for different loads.






28(D) Metering In multi-storied buildings, a number of offices, and commercial centres occupy various areas. Electrical load for each of them would have to be metered separately; the meter-room normally is situated in the ground floor (see IS 15707 for further guidance). (E ) System Protection The general rules for protection for safety laid down in Part 1/Section 7 of this Code shall apply. Reference is also drawn to SP 7 on guidelines for fire protection of buildings. The general rules given below shall apply. The type of buildings covered in this Section fell under Group B (educational buildings). Group E (business buildings) and Group F (mercantile buildings) from the point of view of fire safety classification (see SP 7). Typical fire fighting installation requirements are also covered therein. The electrical needs for the appropriate type of installation shall, therefore, be decided accordingly. Educational buildings (Group B) Educational buildings above 2-storeys having an area of more than 500 m2 per floor shall have besides fire- fighting equipment, manually operated electrical fire alarm and automatic fire alarm systems. Business buildings (Group E) Besides fire-fighting equipment, automatic fire alarm systems are recommended for offices, banks professional establishments, etc, where the buildings are more than 2 storey with floor area above 500 m2 per floor, and for laboratories with delicate instruments as well as computer installations. Mercantile buildings (Group F) Besides fire-fighting equipment, automatic sprinkles and automatic fire alarm systems are recommended for wholesale establishments, warehouses, transport booking agencies, etc, as well as for shopping areas inside buildings with area more than 500 m2 on each floor. For other premises and shopping lines with central corridors open to sky, automatic fire-alarm systems shall be installed. Underground shopping centres shall be provided with automatic sprinkles. (F)Building Services






Lighting The general rules laid down in Part 1/Section 11 of this Code shall apply. The choice of lamps, lighting fittings and general lighting design together with power requirement shall be planned based on the recommended values of illumination and limiting values of glare index given in Table 1. In commercial premises, a fairly high level of glare free lighting on working planes and subdued lighting in circulation areas are necessary. Aesthetics and interior decoration also play a part. Lighting design in showrooms includes high level of lighting in the vertical and horizontal planes, depending on the merchandise exhibited and their layout. Colour temperature characteristics of the light source shall also be taken into account in the case of showroom lighting. Air-conditioning The general rules laid down in Part 1/Section 14 of this Code shall apply. The design of the air- conditioning system, shall take into account the requirements stipulated in the following clauses. In case of large air-conditioning installations (500 tonne and above) it is advisable to have a separate isolated equipment room together with electrical controls. All equipment rooms shall have provision for mechanical ventilation. Lifts and Escalators The general rules laid down in Part 1/ Section 14, of this Code shall apply. However, the design of lifts shall take into account the following recommendations: (G)TESTING OF INSTALLATION The various tests on the installation shall be carried out as laid down in Part 1/Section 13 of this Code.

unit 4

Documents

good lighting design

directional lighting

emergency lighting systems

building design aspects

point of view

surroundings b

good modelling

economic services