1.Codes, Standards and references

The electrical design,manufacture, installation practice and testing of the materials, plantequipment and systems shall conform to the applicable requirement of thefollowing regulations:

• International Electro-technical Commission (IEC)
• International Standardization Organization (ISO)
• Local codes (KSA).
• British standard Specifications (BS)
• National Electrical Codes (NEC)
• National Electrical Manufacturing Associations (NEMA)
• Association Of German Engineers Specifications (VDE)
• German Industry Standards (DIN)
• Illumination Engineering Society (IES)

2. SCOPE OF WORK

The electricaldesign and specifications for the project shall consist of the following:

• Distribution transformer.
• LV distribution boards
• Stand-by Generator and UPS
• Wiring method & cable route.
• Lighting and central control system
• Power & socket outlets.
• Earthing (grounding) system.
• Lightning protection ( Ifrequired )

2.2 Low currentsystems

The special system shall include the following light current systems:

 –FireAlarm System
 – Telecommunicationsystem Networks
 –ClosedCircuit Television (CCTV) Security system
–Master Antenna TV (MATV)
– Automation system

2.2.1Fire AlarmSystem
The fire alarm system shall be based on intelligent analogueaddressable type, Fire Alarm Control Panel (FACP), with voice evacuationsystem, shall be installed on security room to control and report all eventsand actions. Repeater panel shall be installed at the entrance of the buildingin order to report all Main Fire Alarm Control Panel’s events and actions.
Suitable types of detectors at proper distribution shall be used.
The voice evacuation system shall cover all public areas and corridors.
FACP shall be interfaced with other systems such as fire fightingsystem, HVAC, public address, security system, etc.

2.2.2 Telecommunication system Networks
The network shall beuniversal which means that the accessories of the telephone and data outlets(sockets, cables, put-in panels) shall be typical the same, in order to providethe facility of the inter-changeability. So at any time, the data outlet can be converted to telephone outleteasily and vice versa.
The data telephone cabling network system for the building shallsupport the requirements for fast data communications, according to theconfigurations, and the topology of the building, including theoutlet/connector.
The data and telephone connectivity shall be very fast using back bonefiber optical cabling system, with patch panels in the IT rooms, and CAT6 4pairs UTP horizontal network terminated with RJ45 outlets.
The telephone system shall be based on digital PABX private automaticbranch exchange equipment, with capacity and features suitable for the project.
All active components including switches, routers, and servers, alsoPABX shall be out of Scope of Work.

2.2.3ClosedCircuit Television Security (CCTV) system
The Closed Circuit Television system CCTV shall be used for securitysurveillance purpose using video camera.
The management and control of the system shall be fully digital system.Sensitivity of cameras shall fit for clean reproduction of picture with themaximum and minimum intensity conditions of each location.
Indoor camera shall be located at entrance andcorridors.Outdoor camera shall beequipped with full environmental protection enclosures for exits and parkingareas.
All monitoring, controlling and surveillance equipment shall be locatedat security room.

2.2.4MATV
Satellite receivingfacility shall be based on central dish antennas shared by few users.An internal TV network shall be used todistribute the IF signal to the TV wall outlets.
Digital set box receiversshall be used to receive the IF signal which comes from the wall socket.
Television (TV) distributionsystem shall distribute the TV channels received from the interfacingequipment.
The TV channels shall bein the form of RF signals originated from the central receiving station(related to the infra structure contract).
There are also theco-axial cable network and network equipment (signal booster, distributionaccessories, splitters, tap-offs, signal outlets, etc.).

2.2.5Automation system
Automation system shallbe used for monitoring, controlling andmanagement all electromechanical systems including but not limit for electricalpanels, low current systems, HVAC equipments and plumbing pumps/valves.

The management, monitoring and control of the system shall be fullydigital system located at management room.

3. designconcept

3-1 Ambient Design Conditions
The prevailing localclimatic conditions (Relevant to the design and selection of equipment andmaterials for the electrical system) are as follows:
Maximum Ambient Temperature50°C
Humidity Range 6%- 100 %
Blowing Sand and Dust

Power Transformer

Dry type transformersshall be located in separate room in ground floor. The selection to use the drytype transformers rather than using the oil cooled type, is based on taking theadvantage of the following benefits:

• Maintenance free
• Safe to use within the building
• Overload capacity reaches135% when provided with forced ventilation fans

Dry type transformers shall be equipped with tap changer + 2.5%, temperature sensor, thermal relay and forced ventilation fans
Transformerlow voltage output connected to low voltage switchgear via low voltage cablesmounted on cable trays.

3.3 Stand-by Generator

An automatic startstand-by emergency diesel generator shall be provided, located in ground floor(Generator Room).
The generator’s powershall be sufficient to cover the essential lighting loads (25%), some of smallessential power loads, UPS system, telecommunication systems, fire pumps, firealarm control panel, security systems, forced ventilation and exhaust fans,lifts and other life safety loads.

3.4 MainLow Voltage Switchgear 380 V

Electrical power shall bedistributed to the building from the main low voltage switchboards, fed fromthe power transformers.
These switchboards shallinclude main with drawable air circuit breakers, bus coupler and a group offixed type molded case circuit breakers (MCCB). They control and protectelectric supply feeders, up to the load centers or to the distribution panelboards, assigned for every floor.Thisswitchboard shall include the necessary control/operation/protection andmetering equipment.
Main low voltageswitchboard, shall facilitate the automatic and manual change-over between thetwo different transformers via the bus coupler.
Power factor correctionusing automatic regulated capacitor banks shall be provided to improve P.F.value to 0.95 of the main switchboards.
All C.B.S. shall haveservice short circuit breaking capacity, equal to the value of the prospectedshort circuit current.

3.5 Electrical DistributionSystems

Three types of power supplysystems shall be utilized:

• Normal system
• Emergency system (backed-up by the dieselgenerator )
•  

Normal DistributionSystem:Normalpower supply shall feed the entire project through a dedicated panel boards andcabling system.
Electrical loads fed fromNormal power, shall be subject to power supplycut out, during any power failure in the pro­ject normal supply.
EmergencyDistribution System:Emergencypower supply shall feed the electrical loads backed-up by the diesel generatorset(s), through a dedicated panel boards and cabling system.
Main power shall be sup­pliedfrom utility network, during normal condi­tions, and from stand by dieselgenerator set(s) in case of utility outages. Emergency supplied fittings shallbe a percentage of the normal ones, according to the following:

• -Lighting in staff areas and circulation 25%

-Toilets,corridors and executive offices 50%
-Lightingfor reception. 50%
-Lightingfor staircase, entrances and exits 100%
-Securitylighting & E- signature room 100%

DistributionPanel Boards

Panel boards shall bedistributed all over the building and shall be located in the Electrical rooms.Each panel board shall feed and protect type of loads according to their demandclassification. One electrical room, containing all the required panels andrisers, shall serve each floor. 
All panel boards shall be factory assembled and certified according toIEC standards.Enclosures shall be IP 30for indoor flush mounting, IP 43 for indoor surface mounting and IP 54 for outdoor, mechanical rooms and wet areasinstallation.
Distribution boards shall be equipped with molded case circuit breakers,for main CB.Branch circuits shall beprotected with miniature circuit breakers with minimum 10 kA short circuitinterrupting capacity unless otherwise indicated.
All panel boards shall beequipped with phase indicating lamps, door lock and circuit designation sheetcovered with flexi glass.
All panel boards shall beidentified and tagged with warning signs

Earthing (grounding)System

Earthing Electrodes:Earthing electrodes shall be copper cladsteel rod 20 mm diameter, furnished in 3 meterslength, free of any non conductive material coatings and shall be constructedof:

• Pure electrolytic copper minimum thickness of 0.25 mm
• Low carbon high strength core
• Driving stud suitable forpower-hammer driving.

Earthing Conductor:Earthingconductor shall be color coded and sized to comply with the applied codes.
The complete system shall have less than the following ohms earth resistance:

• 3 ohm for medium voltage
• 3 ohm for low voltage
• 10 ohm for lightningprotection
• 0.4 ohm for clean telecommunication earthing

 Cables and Raceways

380/220 V feeders shall be extended from the main low voltageswitchboard at the ground floor to all distribution panel boards located ateach floor and also to other loads serving the building.Feeders shall be sized in accordance with theDemand load, voltage drop, etc.., and allowance is made for future increase inload.
A maximum total voltage dropfrom the transformer/main switchboard to the farthest point of use shall notexceed 5%.
Low Voltage Cables:These cables are of 600/1000 volts,copper conductors, multi-core or single core, PVC insulated and sheathed,non-armored for indoor installations and armored for outdoor installations.Cables designated for Security and life safety loads shall be fire resistanceand flame retardant cables
Low Voltage Wires:Wires shall be 450/750 Volts, copperconductors, single core, PVC insulated, running in PVC conduits for concealedinstallations and in galvanized steel conduits for exposed installations,standard color coding shall be strictly applied. Wires designated for Securityand life safety loads shall be fire resistance and flame retardant wires.
Raceways:Raceways for cables shall be suitable forthe application. For indoor installations Power cables shall be laid onadequately sized cable trays of post hot dip galvanized steel, perforated typeand/or heavy duty galvanized steel ladders. All necessary fittings andaccessories are of the same cable tray/ladder’s manufacturer.Grades of carrying capacities are decided asapplicable to ensure no sagging or deformation.
Concrete open trencheswith chequered steel plate shall be utilized within the plant areas.External cables in site shall be laiddirectly in ground, or shall run in conduit duct banks according to needs.

Lighting System

The lighting installationshall provide an adequate standard of lighting throughout the project.The lighting shall be designed to provideadequate illumination to enable all tasks to be performed safely andefficiently in the various locations and to enable persons to pass from onearea to another in safety.The designshall be such as to minimize glare and to provide an even illumination. In workareas the lighting required is a “white” light with no color effects. Inaddition, the design shall take into account the possibility of an electricitysupply failure and the effects on the lighting system. Generally, the lightingin any one area shall be provided by more than one circuit.
Circuits:PVC, insulated copper wired 4 mm2are used for the secondary lighting circuits, unless otherwise indicated onDrawings.Number of points per circuitand length of wire runs shall be properly considered to minimize voltage drop,avoid crowded runs and ensure easier future maintenance.
These circuits shall beprotected by suitably rated miniature circuit breakers not less than 16 A.
Lighting Fixtures

• Indoor Light Fittings

Types of these fittings areselected based on usage of each area. Local and/or central light switches shall be properly located to ensurethe easiest way of control and best possible energy saving.
Types expected arefluorescent types at parking area, office space area, electrical and data roomsand similar.Fluorescent lamps shall bepower factor corrected to at least 0.9.

• Outdoor Light Fittings

Types expected are Metalhalide for the outdoor light fittings. All external lighting shall becontrolled by photo-electric controller.

PowerOutlets and Convenience Socket Outlets

Circuits:PVC, insulated copper wired 4 mm2protected by 20 a miniature circuit breaker unless otherwise indicated ondrawings.
Power Outlets:Suitable types of local fused switches or isolatorsare provided adjacent to electric loads related to mechanical or HVAC systemssuch as air-handling units (AHU), Fan Coil Units (FCU), pumps, freshair-handling units, etc., to allow easy maintenance of such equipment.
Convenience SocketOutlets:Different types ofsocket outlets are properly distributed to maintain adequate supply points fordifferent types of fixed and/or portable electric appliances. 3 pin, 16 A,earthed sockets are of general use. Another particular type of weatherproof, 3 pinearthed type shall be used in wet/damp areas.
Socket outlets, conduits and boxes are totally segregated from any othersystem.

 Electrical Wiring Devices

Wiring devices shall bein accordance with IEC and local standards and shall conform to the requirement

Reliability

Individual feederdistribution from the main distribution board shall be provided for thefollowing loads:

• Elevators
• HVAC MCCs
• Fire pumps.
• Water pumps
• Sub-distribution boards.
• Other loads.
• External lighting panels