2.19 Electrical Services
2.19.1 Electrical Supply
2.19.1.1 Rated Voltage & Frequency
Electrical equipment shall be selected to comply with the following rated voltages and frequencies.
415V/3ph/50Hz, 240V/1ph/50Hz 2.19.1.2 Loads
The electrical design shall include a schedule of connected and instantaneous loads, which shall be updated during the design process to form the basis of the power supply and distribution capacity. The figures given in Table 29 may be used for estimating purposes.
The power supply and distribution system should be designed with minimum 25% spare capacity to accommodate changes and future expansion.
The overall system power factor, inclusive of reactive power losses in transformers and distribution system equipment, shall not be less than 0.8 lagging at rated design load.
2.19.1.3 Voltage Drop
The voltage drop in cables between LV main switchboard outgoings and consumer terminals shall not be more than 5%, based on continuous maximum current loading and rated voltage.
Moreover, during the starting and stopping of heavy loads, such as chiller compressors, the transient voltage depression at the terminals of any motor shall not be more than 20% of the rated equipment voltage.
Table 29: Estimated Electrical Loads
Facility Maximum Demand
PDO Permanent Camp
Accommodation 4.5 kVA/unit
Laundry / Messing 1.0 kVA/person
Cinema (open air) 4.8 kVA
Clinic 18.0 kVA
Football Pitch 36.0 kVA
Fuel Station 21.0 kVA
Guard House 10.0 kVA
Mosque 14.5 kVA
Shop 10.0 kVA
Squash Court 9.0 kVA
Tennis Court 18.0 kVA
PDO Temporary Camp
Accommodation 3.7 kVA/unit
Laundry / Messing 0.7 kVA/person
Contractor Facility
Accommodation 3.7 kVA/unit
Laundry / Messing 0.4 kVA/person
Workshop (open sheds) 30.0 kVA/unit
Broad brush 30.0 VA/m2
2.19.1.4 Underground Cable De rating
While the sizing of above ground cables shall be in accordance with the IEE Regulations (refer section 1.4.3 for the IEE), a basic de-rating factor, depending on cable size and type, shall be used for underground cables. The figures given in Table 30 shall be used a catchall factors.
A further de-rating factor shall be applied relating to the grouping of cables.
Table 30: Overall De rating Factors for Underground LV Cables (Note: Not applicable to cable groups)
Cable De rating Factor
Up to 150 mm2 0.61
LV cables sizes 16 mm2 and above shall be copper conductor, cross-linked polyethylene insulated, steel wire armoured, polyvinyl chloride sheathed (XLPE/SWA/PVC).
LV cables sizes 2.5 mm2 to 10 mm2 may be PVC insulated, copper braid armoured, PVC sheathed, (PVC/SWB/PVC).
2.19.1.6 Earthing
Earthing systems shall be provided in accordance with SP-1099 Specification for Electrical Installation Practice section 2.3, ‘Earthing Systems’. The system of earthing shall be TN-S, that is, protection against indirect contact obtained by earthed equipotential bonding and automatic disconnection of supply.
Minimum ring cable size shall be 70 mm2, minimum radial cable size shall be 25 mm2. 2.19.2 Small Power
Appendix L includes the following small power requirements relating to Company facilities.
- Power outlets
- Shaver outlets
- Hand dryers
- Fire alarm systems - Airconditioners
- Ventilation fans
- Water heaters
- Drinking water coolers - Cookers
- Refrigerators - Insectocutors
SP-1099 Specification for Electrical Installation Practice, gives the Company Electrical Standards for the following.
- Applicable Standards, Specifications & Codes
- General Requirements
- Cable Installation
- Earthing Systems
- Hazardous Area
- Equipment Installation
The Company Electrical Standard Drawings lists are contained in SP-1105 Specification for Electrical Standard Drawings List.
2.19.2.1 Power Supply
Electrical designs shall include distribution board and feeder pillar single line diagrams showing:
- Board reference, area served and location.
- Incoming feeder cable size and reference.
- Circuit MCB/RCD protection sizes.
- Sub circuit ways, outgoing feeders, MCB/RCD/ELCB protection ratings, wire sizes and sub areas served.
- Sub circuit loads and total connected load per phase.
- Min 25% spare outgoing feeders (refer section 2.19.1).
Distribution boards shall incorporate residual current type earth leakage circuit breakers to provide discriminatory protection as follows.
- Distribution Board feeders: 100mA - Socket outlet ring sub circuit: 30mA
Distribution boards shall not be located within toilets or ablutions. Neither power outlet nor switch shall be located within 1 m of a water source, or under a water pipe.
A means of identifiable local isolation shall be provided for each connection to electrical equipment.
2.19.2.2 Power Consumption
All single-phase loads shall, as far as is practically possible, be evenly distributed over the phases.
2.19.2.3 Voltage Drop
Refer section 2.19.1.3 of this specification for voltage drop.
2.19.2.4 Cables
Armoured cables shall be as described for underground cables in section 2.19.1.4.
Cables in conduit or trunking shall be copper conductor, PVC insulated. Minimum size shall be 2.5 mm2.
2.19.2.5 Conduit & Trunking
PVC conduit shall be used only inside buildings in locations not liable to mechanical damage. Only GI conduit shall be used for external work. Minimum conduit size shall be 20 mm. Design drawings should indicate the number and use (line, neutral and protective earth) of cables in each conduit.
GI trunking should be used instead of multiple conduit runs. Trunking that is intended for the accommodation of different services shall be divided into separate compartments to provide complete cable separation.
Steel conduit and trunking shall be electrically and mechanically continuous throughout.
2.19.2.6 Earthing & Bonding
Earthing and bonding installations shall be shown on the electrical design drawings. All metallic electrical equipment enclosures shall be earthed as described in section 2.19.1.6.
Exposed metalwork of all conduits, trunking, ducts, sheaths and armouring of cables, and all fixed metalwork which is in reach of electrical apparatus, shall be bonded and earthed. Such other fixed metalwork required, to be bonded and earthed shall include exposed metal pipes, sinks and tanks.
The earth bonding connection to any water services entering a building shall be as near as possible to the point of entry, after the isolation valve.
Minimum cable size for bonding metal pipes, sinks and the like shall be 6 mm2. 2.19.3 Indoor Lighting
General requirements for the illumination of Company facilities are given in Appendix L.
Where requirements are not listed in Appendix L, illumination levels should follow the standards listed below: Indoor lighting design should comply with the recommendations of the following.
BS 8206: Code of Practice for Artificial Lighting.
BS ISO 8995: Lighting of Indoor Work Places CIBSE: Code of Interior Lighting.
2.19.3.1 Luminaries
As well as first cost, lamps should be selected for long life, giving reduced maintenance and replacement costs, and low energy consumption. Where special requirements for colour rendering exist, they should be met. Incandescent lamps should only be used for decorative purposes. Low pressure sodium discharge lamps should not be used since they represent a fire hazard in the event of breakage. Table 31 gives typical lamp selections for standard applications.
Table 31: Typical Indoor Lamp Selection
Application Lamp
General Fluorescent Types 2D,PL,SL,TL
Industrial Fluorescent Type TL, white
High bay HP discharge Type MBF
Fluorescent Ex e
Zone 1 & 2
HP discharge Ex d
Luminaries located in ablution and toilet areas shall be protected to IP54, in special cases, for example, where cleaning is by water hose, IP55 may be required. Light switches in ablution and toilet areas shall be pull cord operated.
Luminaries, surface mounted on ceilings of combustible material, shall be offset by 50 mm.
2.19.4 Emergency Lighting
Emergency lighting systems cover escape route lighting, exit sign indication and vital lighting.
The function of emergency lighting shall be to:
- Indicate the escape routes clearly and unambiguously.
- Provide illumination along such routes to allow safe movement towards and through the exits provided.
Ensure that the fire alarm call points and fire fighting equipment provided along escape routes can be readily located.
- Provide illumination to a facility which, when failing in operation, can cause an unsafe condition or can result in major damage.
Escape route and exit lighting shall be located at each exit door, emergency exit door, and where necessary to identify potential hazards, that is,
- At corridor intersections - At corridor changes of direction - At stair flights
General requirements for escape route and exit lighting are given in Appendix L.
An un-switched power supply shall be provided to keep the battery backup packs on charge, and to sense mains failure.
Emergency lighting system design, installation and implementation shall confirm to the requirements of BS 5266, Emergency Lighting.
2.19.4.1 Escape Route Lighting
Fixed escape route lighting shall actuate within 5 sec of normal lighting failure.
Illumination should be not less than 0.2 lux.
Light fittings should be non-maintained, self contained, slave luminaries, operated by a DC battery which shall be capable of 3 hour running time. Alternatively, battery backup conversion kits may be used on selected lamps to enable fluorescent luminaries to operate as emergency lighting.
2.19.4.2 Exit Lighting
Exit light fittings should be maintained, self-contained slave units, with 3 hour battery backup.
EXIT lettering, in Arabic and English, shall be green on a white background.
2.19.4.3 Vital Lighting
In cases where vital lighting is required for operational purposes, battery backup conversion kits should be used in a proportion of the standard light fittings.
Appropriate vital illumination levels should be calculated in each case, but in the absence of definitive data, the number of vital lamps as part of the total number of lamps may be determined using Table 32.
Table 32: Typical Vital Lighting Requirements
Area Vital Lamps
Administrative Area 5%
Computer Room 10%
Control Room 50%
Field Auxiliary Room 30%
Switch House 30%
Utility Area 20%
Clinic Ward 25%
2.19.5 Outdoor Lighting
Outdoor lighting installations shall comply with SP-1099 Specification for Electrical Installation Practice section 2.5.5 Lighting.
2.19.5.1 Lighting Fixtures
Outdoor lighting fixtures shall be located a minimum distance of 0.5 m from the face of roadway kerbs and a minimum 1.5 m from the face of car park kerbs.
Polycarbonate diffusers shall not be used unless they are certified as UV resistant.
Table 33 includes preferred lamp types for outdoor lighting applications.
2.19.5.2 Illumination Levels
Table 33 also gives minimum maintained illumination levels for outdoor lighting.
Table 33: Typical Outdoor Lighting Lamps & Illumination Levels
Application Lamp Type Illumination
Football Pitch SON 150 lux
Lay down Area MBF 50 lux
Operational Area MBF 10 lux
Roadway MBF 10 lux
Tennis Court SON 200 lux
Volleyball Court SON 200 lux
Walkway MBF.2D 10 lux
Workshop MBF 50 lux
2.20 Fire Detection & Alarm
The Company fire detection and alarm design parameters are set out in SP-1075 Specification for Fire, Explosion & Risk Management. General requirements are given in Appendix L. For the fire detection and alarm equipment and materials shall comply with the requirements as given in SP-1285-D Specification for Civil & Buildings Utility Services – ‘Fire Protection Works’. The above are considered as being the minimum standard, however each project shall be reviewed for particular requirements at the design stage.
2.20.1 Operational Criteria
Power supplies for fire detection and alarm systems shall include a standby battery and automatic charger, and shall be designed so as not to become inoperative in the event of failure of the power supply. In general, stand by power supply shall be designed in accordance with DEP 33.65.50.31-Gen. ‘Static DC Uninterruptible Power Supply (DC UPS) Units’.
The main supply feeding the local annunciator panel shall be connected to a dedicated circuit way on a distribution board which is part of the main switch panel. No other service shall be connected to this circuit way and, where MCBs are used, the one serving the fire protection system shall be coloured red and labelled, white/red/white, FIRE ALARM-DO NOT SWITCH OFF (consideration should be given to providing a key switch; the key being held by the fire officer). The main supply cable should follow the least hazardous route available.
The battery backup power supply shall provide at least 24-hour of system operation plus 15-minute of full alarm.
The battery charger shall be capable of restoring the battery to full capacity within 8 hours from fully discharged condition. Fault monitoring and alarm indication shall be provided for:
a. Main power failure by red light without opening the panel b. Battery power failure indication
c. Charger output failure indication
A closed circuit principle shall be used, and all wiring shall be continuously monitored such that any of the following conditions cause a FAULT indication at the local annunciator panel.
a. Short circuit fault, indicating the affected zone.
b. Open circuit fault, indicating the affected zone.
c. Earth fault.
d. Power supply fault.
The control circuitry shall be so arranged such that none of the above conditions cause the fire alarms to sound. Monitoring of the system shall be intrinsic in the control circuit design and shall be automatic in operation, and shall not require manual operation of switches or other apparatus.
Large buildings shall be suitably zoned in accordance with BS 5839 Fire detection and Alarm system for buildings.
The local annunciator panel shall be located at the building main entrance and shall be visible from outside the building. The panel shall indicate zone FAULT, and zone FIRE which shall be activated by manual call points and automatic detection systems. Activation of one zone alarm shall operate audible alarms on all zones. Activation of one zone alarm shall also shutdown airconditioning systems in all zones except for systems that do not cause the spread of smoke outside the area of the fire. FAULT and FIRE alarm shall be relayed to a central mimic panel, at a location specified by the Company.
2.20.2 Cables
Fire alarm and detection cables shall be segregated from other electrical services, including those of similar voltage and frequency.
Cables shall be protected by armour, conduit or trunking. Buried cables shall have steel wire armour and cables encased within building fabric may be in PVC conduit. Cables should be exposed only in industrial applications.
Cables should be single copper conductor, minimum size 2.5 mm2 for low voltage (240v) and minim size 1.13 mm2 for very low voltage (to 30v).
Mineral insulated cable should not normally be required for fire detection and alarm systems.
2.21 Lightning Protection
Lightning protection requirements, if any, should be based on the factors listed below and shall be agreed with the Company.
- Exposure risk - Use of structure - Type of construction
- Contents or consequential effects
- Height of structure and degree of isolation - Location topography
Lightning protection system designs should follow the requirements of BS 6651, Code of Practice for Protection of Structures Against Lightning.
2.22 Telecom Networks
The design of telephone distribution systems shall be agreed with and approved by the Company Telecommunications Projects Department (TCT). The building services design shall include, but not be limited to, allocation of reserved rights of way, external layouts, internal layouts and schematics. A key sheet may also be required.
The project scope of work, and the interface between the building services contractor and the telecoms contractor, shall also be agreed with TCT. Normally, this will exclude the pulling and the terminations of external telephone cable but will include the distribution points, telephone outlets, and terminations at the distribution points, conduit and wiring, and terminations at the outlets.
Company supplied materials, which are free issue to the building services contractor, shall be specified by TCT. Normally, they will include:
- Underground ducting
- Distribution boxes - Manhole accessories
Underground cables and handsets are installed by Telecom Specialist Contractors.
General requirements for telephones are given in Appendix L.
The Company Standards for cable laying, manhole construction, duct installation and for installation within buildings is given in PDO-ERD-71-01, Installation of Underground and Internal Telephone Cable Networks.
2.22.1 Data Communications Networks
The scope of building services design should normally be confined to the provision of distribution ways, conduit, trunking or trays, and outlet points together with spatial requirements for equipment.
The scope and design shall be agreed with approved by the Company Telecommunications Department (TCT).
2.22.2 Television & Video Networks
Normally, provision for TV shall be confined to built-in conduit and outlet points.
However, in cases where reception for individual buildings is not possible, a central antenna system may be provided. For camps in the Oman Interior, a VCP system, as well as a satellite dish, may also be included.
Concept design shall be part of the building services scope with detail design provided by a Specialist Vendor. Both concept and detail design shall be subject to Company approval.
General requirements for TV outlets are given in Appendix L.
2.22.3 Audio Systems
Concept and detail design scopes shall be as described in section 2.22.2.
2.22.4 Nurse Call Systems
Concept and detail design scopes shall be as described in section 2.22.2. General requirements for Nurse Call systems are given in Appendix L.
Appendices
Appendix A: Glossary of Definitions & Abbreviations Appendix B: Weights of General Building Materials Appendix C: Typical Live Loads & Finishes Appendix D: Wall Finishes
Appendix E: Floor Finishes Appendix F: Skirting Appendix G: Ceilings Appendix H: Door Types
Appendix I: Window Types (Glazing) Appendix J: Ironmongeries
Appendix K: Internal Environment Design Criteria Appendix L: Electrical Requirements
Appendix M: SP User Comment Form
Appendix A: Glossary of Definitions & Abbreviations
For the purposes of this document, the following definitions, terminology and abbreviations shall apply.
A.1 General Definitions & Terminology
Shall : The word 'shall' indicates a requirement Should : The word 'should' indicates a recommendation the Company : Petroleum Development Oman L.L.C., the
Contractor : The party with which the Company has entered into a Contract Manufacturer : A Party responsible for the manufacture of equipment and services to
perform the duties specified by the Consultant or the Company.
Vendor / Supplier:
: A party responsible for the supply of equipment, materials or product related services in accordance with the purchase order issued by PDO or it’s nominated purchasing office.
Local Agent : An authorised agent of a Manufacturer in the Sultanate Of Oman who can supply the product and services.
National Product
: A product defined as a National Product, in origin manufactured in the Sultanate Of Oman as per the General Conditions of Contract.
GCC Product : A product defined as a GCC Product, in origin manufactured in GCC country as per the General Conditions of Contract.
Works : The permanent Works to be executed and maintained in accordance with the contract together with all temporary works of every kind required in or about the execution or maintenance of the Works.
Workshop : A defined place, approved by the Company, where the Contractor executes fabrication works.
Worksite : The land and other places on, under, in or through which the Works are to be executed.
the User : The Company, and/or Consultant, designate using this document.
Temporary Structures
: Any member or structure which needs to withstand loads and forces of a temporary nature, such as scaffolding, erection bracing, steel props, commissioning facilities, etc. The word ‘temporary’ shall be understood as a short period, limited to maximum of 2 years.
Semi Permanent Structures
: Any member or structure which needs to withstand all meteorological conditions, loads and forces of a permanent nature, but designed for a short period. The word ‘semi-permanent’ shall be understood as a relatively short period, limited to maximum of 4 years.
Permanent
Structures : Any member or structure which needs to withstand all meteorological conditions, loads and forces of a permanent nature, but designed for a long period. The word ‘permanent’ shall be understood as a relatively long period, say 30 years or more.
A.2 Abbreviations
The following abbreviations are used in this document.
AASHTO : American Association of State Highway and Transport Officials ACI : American Concrete Institute
ACV : Aggregate Crushing Value.
ASME : American Society of Mechanical Engineers ASNT : American Society Non-Destructive Testing ASTM : American Society for Testing and Materials
ASME : American Society of Mechanical Engineers ASNT : American Society Non-Destructive Testing ASTM : American Society for Testing and Materials