Available fault current margin calculator

Preliminary estimate

Inputs

Calculation note

This compares entered values only. It does not calculate available fault current, validate AIC/SCCR, or approve series ratings.

Method

Utilization percent = available fault kA / equipment rating kA x 100

Margin kA = equipment rating kA - available fault kA

Required with margin = available fault kA x (1 + safety margin percent / 100)

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Formula variables

  • Available fault kA is entered from an external project source.
  • Equipment rating kA is the marked or specified rating being compared.
  • Safety margin percent is an optional user-entered allowance.
  • Required with margin is compared against the entered rating.

Assumptions

  • Available fault current is entered by the user from a study, utility value, or project estimate.
  • Equipment rating is entered from the actual equipment label or project requirement.
  • Safety margin is a user-entered review allowance.
  • This calculator does not calculate available fault current, verify AIC/SCCR, approve series ratings, or replace coordination study review.

Examples

Label comparison. 14 kA available against a 22 kA rating with 10 percent margin gives 63.6 percent utilization and 8 kA direct margin.

Study workflow. Use the actual fault-current study, utility contribution, equipment labels, and series-rating documentation before equipment decisions.