| Capital Projects Home Page |
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| Division 16 Electrical |
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| 16-3 | Electrical Distribution |
| A. | Campus Electrical Distribution |
| See Special Requirements for barricades at trenches and for utility shutdowns and scheduling. See Division 2 for additional electrical requirements including route approval, service locations, demolition, excavation scheduling, and backfill requirements. |
| 1. | The campus underground primary system is 12000 volt Delta. Unless otherwise noted, all new campus electrical systems shall be 12000 volt. |
| 2. | New building projects should include the installation of two feeders, the splicing into the campus distribution system, and a feeder selector switch. If the local distribution system does not have the needed capacity, the project shall also include the installation of the feeders to the substation and the feeder switches in the substation. If a building is being replaced with a new building, feeders and substation switches may be reused if they are adequate. The project shall also include the installation of a new duct bank if spare conduits are not available in existing duct banks. |
| 3. | High Voltage Duct Banks: Duct banks containing 4160 volts or higher may include conduits for other services such as communication, computer, fire alarm, and street lighting units ‹ unless they terminate in separate handholes and they DO NOT run through the high-voltage manholes. |
| 4. | High Voltage Equipment Rooms: High voltage electrical rooms shall be dedicated to high voltage equipment and their accessories ONLY. Separate rooms shall be provided to include utilities such as telephone, energy monitoring and communication equipment. |
| 5. | Mechanical equipment and piping shall not be installed inside or run through high voltage electrical rooms. |
| B. | Building Electrical Distribution |
| The campus building electrical distribution system standard is 120/208 or 277/480 volts, 3-phase, four-wire, for lighting and power, unless otherwise directed by Planning, Design and Construction (CP). |
| C. | Main Switchboard |
| 1. | Main switchboards shall be copper bus units for metal clad switchgear, drawout type airbreakers or molded case circuit breakers. |
| 2. | Where ground fault protection is required by NEC or these guidelines, main distribution feeder circuit breakers shall be equipped with ground fault protection. See additional requirements in this division. The engineer shall establish pick-up settings for a coordinated building system. Protection shall also be included for phase to phase arcing faults. |
| 3. | All applicable requirements in this division also apply to switchboards. |
| D. | Metering Equipment |
| 1. | Volt-amp reactive meters shall be installed for transformers of 1000 KVA and larger. |
| 2. | Install complete building metering equipment. The equipment shall meter the entire three-phase electrical service used by the building. |
| a. | Electric meters shall have watt (power) transducer to measure true electrical power. The watt transducer shall be of electronic type with high accuracy. |
| b. | The watt transducer shall utilize stable and high linearity multiplier. |
| c. | The pulse multiplier shall work based on PHW principle. |
| d. | The watt transducer shall have two separate pulse outputs, calculated to output one pulse per KWH. Each pulse output shall be either dry contact or opto-isolated type. |
| e. | A counter/totalizer with 8-digit LCD reading and internal 10-year battery shall be installed in the same panel with watt transducer. |
| f. | Installation: |
| i. | The input (high voltage) connections shall be in accordance with the manufacturer's instructions. |
| ii. | The counter/totalizer shall be installed behind a panel window so it can be read clearly without opening the panel door. |
| iii. | The output connection shall be as follows: |
| A. | One of the pulse outputs shall be connected to the counter/totalizer. |
| B. | The DC voltage/current power output signal and the other pulse output shall be reserved for the building Energy Management System. |
| E. | Motor Disconnect Switches |
| Specify heavy duty HD disconnect switches. Thermal overload type switches may act as disconnect where used to protect small single phase motors. |
| F. | Transformers |
| 1. | Where possible, transformers and primary protective gear shall be specified in the prime building contract for single responsibility for power supply. |
| 2. | Specify transformers as dry type, single phase or three phase, three winding, 60 cycle, primary and secondary voltages as required, with four 2.5% taps above and two 2.5% taps below rated voltage. Copper windings are required. No open aluminum windings are allowed. Use cast coil type transformers in outdoor locations. Transformers shall operate under full load with noise level not to exceed American National Standards Institute (ANSI) and National Electrical Manufacturers Association (NEMA) standards. Transformers shall have 220°C insulation, 150°C or 115°C rise. Enclose primary terminals. Extend secondary terminals through the case by means of silvered copper bus bars, include lugs and bolts for cable termination. Check these details with Capital Projects (CP). Design and build transformers in accordance with National Electrical Manufacturers Association (NEMA), ASA and AIEE standards with minimum of 4.0% impedance. |
| 3. | Transformer configuration may be either standard package substations with main breaker equipment and low voltage tie breaker for emergency situation or three single phase wye connected transformers. |
| 4. | Final selection will be based on building use, available space, interrupting capacity, energy losses, maintenance and first cost. Conduct life cycle analysis to select optimal transformers. Discuss these items with Capital Projects (CP) for approval of final selection before preliminary drawings are started. |
| 5. | Locate transformer for quick and easy replacement. |
| 6. | The main high voltage switch before a building transformer should be a 3-way, oil filled, load break, dual handle, fused switch; a Trayer Type or equivalent switch which allows for paralleling two circuits. |
| 7. | Specify primary disconnect switch consisting of metal clad switchgear with vacuum circuit breakers of adequate interrupting duty. |
| 8. | Place all main electrical equipment serving a project or building such as primary switch, transformers and main switchboard in a separate room or vault, which will be accessible only to qualified electrical personnel. Do not locate other equipment in this room. Follow code strictly in the design and provide adequate and legal working space and clearances. Pay attention to accessibility at the rear of the switchboard. If the equipment is not placed in a separate room, it shall be enclosed by a legal screen or chain link fence, properly grounded. Discuss with Capital Projects (CP). |
| 9. | Seismic Bracing and Mounting: Provide calculations stamped and signed by a registered civil or structural engineer which certify that the equipment construction and the manufacturer's recommended method of mounting will comply with Title 24 seismic requirements. Documentation shall show anchors, bolt sizes, quantities and embedment. |
| G. | Distribution Panels |
| Bus shall be copper, no aluminum allowed. Power panelboards shall be dead front, totally enclosed, convertible type, with circuit breakers. See this division for additional requirements. All spaces shall be furnished with breaker mounting hardware. Provide a grounding bus in all distribution panelboards. Grounding bus shall be easily distinguishable from neutral bus. |
| H. | Lighting And Receptacle Panel Boards |
| 1. | Specify general purpose 20 AMP minimum bolt-on circuit breakers for 120/208 and 277/480 volt panelboards, Westinghouse, General Electric, or equal. Minimum interrupting capability shall be 10,000 amperes for 120/208 volts and 14,000 amperes for 277/480 volts. Confer with Campus Electrical Engineer for available fault current levels. |
| 2. | Provide main circuit breakers in panelboards unless directed not to do so by Capital Projects (CP). When more than one panelboard is fed by the same feeder, provide a main circuit breaker in each panelboard. |
| 3. | Locate all busses in the rear of the panelboard cabinet. Mount circuit breakers on suitable supporting members at the front of the cabinet and connected with suitable straps or lugs to the bussing in the rear of the cabinet. Individual circuit breakers shall be removable from the cabinet without disturbing the bussing in any way. Specify door-in-door arrangement. Adjustable trim clamps are not acceptable. Surface mounted panelboards may have the front mounted on a piano hinge on the right side, with double locked doors. |
| 4. | Specify all locks on panelboards in a single building so that all the outer locks of the door-in-door assembly are keyed alike and all the inner locks of the door-in-door assembly are keyed alike, but different from the outer locks. |
| 5. | Detail the layout and dimensions of special-sized panelboards on the drawings. |
| 6. | Specify engraved bakelite nameplates on front of panelboard cover door. Nameplates shall be fastened to the panelboard cover with machine screws. |
| 7. | Show three 1-inch spare conduits from panelboards to accessible space above furred ceilings, to allow for use of spare circuits or spaces provided in the panelboards. Spare conduits shall be capped off in accessible space above furred ceilings. |
| 8. | Percentage of spares and spaces in panel for future growth shall be 20%. Provide hardware and bus taps for installation of future breakers in spaces provided in panelboard. |
| 9. | Specify bolted copper bussing. No aluminum allowed. |
| 10. | Contractor shall balance phases during normal building operation. |
| I. | Ground Fault Protection |
| 1. | Specify ground fault protection at the distribution panel for each breaker for circuits serving wet or hazardous areas including outdoor branches, bathrooms and laboratories with sinks. Discuss with Capital Projects (CP) for other potential hazardous areas. |
| 2. | Provide ground fault protection at the main breaker of the main switchboard for building transformers of 1000 KVA and larger. |
| J. | Motor Control |
| 1. | Gutter-mounted motor control centers consisting of starters and fused switches are not acceptable. Provide circuit protection in the form of circuit breakers mounted in suitable panels. Provide safety disconnect switches per code at all remote motor locations. Motor starting controls may be centralized in a single panel if a sufficient number is involved. Comply with requirements of the Energy Management Control System for wiring, fusing, and related work. |
| 2. | Indicating and pilot lights shall not be neon or LED type. |
| 3. | For motor control centers serving loads at voltages above 120 volts, use 120 volt control circuit furnished by a control transformer within the motor control center and connected to the bus. Motor control centers shall be General Electric, Allen-Bradley, Westinghouse, or equal. |
| 4. | In buildings with large equipment power demands, limit building restart load after power interruptions. Use three wire protection on all large motors such as supply and exhaust fans and other equipment susceptible to damage from automatic restarts. Discuss which motors should have this type protection with Planning, Design and Construction (CP). |
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