Frederick Community College Facilities Master Plan Chapter 6 Recommendations, Campus Development 6-C-4 May, 2023 Table 3: Existing and Future Heating Demand Summary Central Plant Cooling Demand (Tons) Campus Cooling Demand (Tons) Existing 8,880 9,875 Future (2023-2033) 13,035 15,640 Net Increase 4,155 5,765 Electrical Infrastructure While existing Switchboard MDP has adequate spare capacity to serve additional load, the current incoming service arrangement with the six disconnects limits the ability to install additional fusible switches or circuit breakers. The National Electrical Code (NEC) dictates a maximum of six service disconnecting devices may be connected to the incoming service. Since Switchboard MDP does not have a main disconnecting device, the six devices which currently exist will not allow the installation of additional disconnecting devices to be connected to the incoming service. Coupled with the 29-year age of the switchboard, it is recommended the main switchboard be replaced. The new switchboard will be rated for a minimum of 3,000 amp at 480/277 volts and will be provided with a single main circuit breaker. This will allow an unlimited quantity of feeder circuit breakers to be incorporated into the switchboard when it is initially installed and should they be needed in the future. It is recommended the new switchboard be installed in an alternate location which will allow the existing switchboard to remain in service. The new switchboard will be provided with a 100% rated, 1200 amp, 3 pole feeder breaker to back feed the existing switchboard. Once the new switchboard is energized, the existing incoming service will be de-energized, and the new switchboard will be used to back feed the existing switchboard through this 1200-amp circuit breaker. This will minimize downtime for the central plant which provides heating and chilled water to most of the campus. As new chillers are installed, they will be connected to the new switchboard which will allow the old feeder serving the associated chiller to be removed. The goal is to remove all mechanical equipment connections from the existing switchboard and have them served by the new switchboard. Once all connections have been removed from the switchboard, it can be removed in its entirety. Concurrent with the installation of the new switchboard, two distribution panels will be provided and will be served by the new switchboard. Each distribution panel will provide service to half of the boilers and heating water pumps. Half of the chilled water, cooling towers and condenser water pumps will also be served by each panel. This distribution scenario will allow 50 percent of the heating and cooling systems to operate should a panel need to be turned off to add additional circuit breakers. As new mechanical equipment is being provided, it will be connected to the new distribution panels. Existing feeders will be removed back to the existing motor control centers and panels serving the equipment. Once all equipment is removed from the existing control centers and panels, then they can be removed inclusive of their associated feeders.
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