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6.6 Electrical Load Analysis

In establishing electrical loads for federal buildings it is important to look beyond the immediate requirements stated in the project program. Future moves and changes have the effect of redistributing electrical loads. The minimum connected receptacle loads indicated in Table 6-1 combined with other building loads multiplied by appropriate demand factors, and with spare capacity added, shall be used for obtaining the overall electrical load of the building. If the load requirements stated in the program are higher, the program requirements must, of course, be satisfied.

Standards for Sizing Equipment and Systems
To ensure maximum flexibility for future systems changes, the electrical system must be sized as follows: panel boards for branch circuits must be sized with 50 percent spare ampacity, panel boards serving lighting only with 25 percent space switchboard ampacity, distribution panels with 35 percent spare ampacity and main switchgear with 25 percent spare ampacity. Spare overcurrent devices shall be provided as well as bus extension for installation of future protective devices.

Table 6-1 Minimum Connected Receptacle Load

  Minimum connected receptacle load
Type of occupiable area Load per square meter Load per square foot
Normal systems  
Office/Workstation 14 VA 1.3 VA
Non-workstation areas such as public and storage 10 VA 1 VA
Core and Public areas 5 VA 0.5 VA
Electronic systems  
Office/Workstation 13 VA 1.2 VA
Computer rooms 700 VA 65 VA
NOTE: Normal and electronic equipment systems are as shown on Figure 6-2

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