McLARNEY RESOURCE LIBRARY

 

GENERAL ELECTRICAL SERVICE INFORMATION

 

Note:  This information is for general reference only and is not a substitute for actual design calculations.

                                                 Ampacity at     Wattage at                Ampacity at        Wattage at

Electrical Service Size            120-208 volts  120-208 volts           480-277 volts     480-277 volts

          400 amps                                        400              144000                            400                 332000

          600 amps                                        600              216000                            600                 498000

          800 amps                                        800              288000                            800                 664000

        1000 amps                                      1000              360000                          1000                 830000

        1200 amps                                      1200              432000                          1200                 996000

        1600 amps                                      1600              576000                          1600               1328000

        2000 amps                                      2000              720000                          2000               1660000

        2500 amps                                      2500              900000                          2500               2075000

        3000 amps                                      3000            1080000                          3000               2490000

        4000 amps                                      4000            1440000                          4000               3320000

Please note:  The above calculations are for 3 phase services only.

To calculate the building’s watts per square foot, simply divide the Service Wattage by the building’s square footage.

Example:  For a 50,000 sq. ft. Building with a 1200amp/480-277 volt service.

 

1200amp / 480-277 volt = 996,000 / 50,000 = 19.80 watts per square foot.