Skip to content
Open calculators

Main Switch and Supply Capacity Checker

Compare a calculated demand current with main-switch, supply and reserve-current limits.

Inputs

Project inputs and assumptions

Range: 0–100,000 A

Enter the demand current from a defensible load assessment.

Range: 0.1–100,000 A

Enter the selected main-switch rating from the equipment data.

Range: 0–100,000 A

Enter the confirmed usable supply capacity at the connection point.

Range: 0–100,000 A

Reserve capacity that must remain after the current project demand.

Result

Main-switch margin (A)
18.00
Supply shortfall (A)
0.00
Supply-capacity margin (A)
8.00
Usable supply after reserve (A)
90.00

Formula

Calculation logic

Formula definitions and substituted values.

Before relying on the result

  • Check whether a main switch rating exceeds calculated demand
  • Screen a supply upgrade or planned-load shortfall
  • Compare the result with the actual supply authority conditions, installation rules and equipment ratings before selecting a main switch or service.

Related calculators

Compare the result with the actual supply authority conditions, installation rules and equipment ratings before selecting a main switch or service.