GS / CALCULATOR

ATS sizing calculator

Choose a transfer switch ampere rating from load current and design factor.

Start calculating
Automatic transfer switch cabinet with dual incoming supplies and an interlocked mechanism
GS / INPUTS

Select an initial transfer switch current rating

Specify load current and the project design factor. The tool selects the next listed rating at or above design current.

Inputs

Result315 A
Design current
312.5 A

The suggested ampere rating considers current only. Verify voltage, poles, load class and short circuit withstand separately.

Calculation method

Design amps = load amps × design factor

Interpreting the result

Ampere rating alone does not complete ATS selection. Poles, short-circuit withstand, protection coordination and transfer mode must match project requirements.

The result is an initial estimate based on your inputs. Check equipment nameplates, manufacturer data, installation conditions and project requirements before final selection.

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