:: Intellitech ::

For new facilities with multiple buildings, the electrical service shall typically be received from the local utility at a single location. Electrical service to buildings at the facility shall be extended on a customer-owned distribution system. The use of either a medium voltage, or a 440V distribution system shall be considered. The distribution system design choice shall be based on the facility’s layout, loads, etc. Power for emergency and standby systems shall be provided from a centrally located generator serving multiple buildings, or from separate generators installed in each building. Life-cycle costing analysis shall be performed to back up distribution system design choices.

The electrical distribution system shall meet the requirements of the state agency code and the National Electrical Code. Pay particular attention to the requirements of providing emergency power; - emergency power to end life safety devices shall be provided from the emergency power source as an unbroken distribution system separate from the normal distribution system. Note: multiple automatic transfer switches shall be utilized when serving emergency and standby loads from an emergency generator.

Most of the larger existing State facilities have normal power distributed by an existing State-owned underground distribution system. Power for emergency and standby systems is typically provided from generators installed within each building, or from a centrally located generator serving numerous buildings. Electrical service for new buildings in these existing facilities shall be extended from the existing State-owned distribution systems. The existing site distribution will dictate the design of a new building’s normal and emergency power distribution systems. It is the responsibility of the system designer to verify existing system capacity when adding new building loads to an existing State-owned distribution system.

When calculating the electrical service and feeder sizes for buildings, pay particular attention to the connected load, standard power factor, wiring standard and distance of complete layout plan.

The majority of system voltages presently used within buildings include 220/230V, 440/230 V, and 440 Delta. For large motor loads and large lighting loads, 440volt systems shall typically be used.

For building services where the code requires ground fault protection on the main service disconnect, ground fault protection shall also be provided on the next level feeder breakers, to aid the coordination.

Set points for the distribution system’s overcurrent and ground fault trip adjustments (electronic trip circuit breakers and protective relays) shall be addressed. The system designer shall provide the set points, or coordinate with the equipment manufacturer to provide them. If the equipment manufacturer is to provide the set points, the system designer shall provide information as required for the manufacturer to perform the coordination study. The system designer shall approve the set point recommendations and shall verify that the devices have been properly set.

The consultant shall work with the architect to ensure that adequate accessible indoor space is identified for distribution equipment that is to be installed indoors.

For new or remodeled buildings, make sure that an electrical meter that measures total building kWh and kW demand is provided.

Power and signal systems shall be provided between buildings as separate manhole and ductbank systems. Spare conduits for each system shall be provided. The consultant shall inquire about the long-range plans for the site, and shall size the ductbanks from the distribution point accordingly.

The program statement for new facility or building projects shall be reviewed, and may specify additional distribution system requirements, such as providing redundant generators or emergency feeders, sizing generators to back up the entire facility, providing equipment to parallel generators with the utility, or providing closed-transition switching.