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Transfer Switch Sizing Calculator

Sizes an automatic or manual transfer switch in amperes from the connected standby load, using the standard continuous-load 125% factor, then rounds up to the next standard commercially available switch rating.

AAJappsEngineering Calculation Report

Transfer Switch Sizing Calculator

NEC 700/701/702 continuous-load practice (125% continuous, 100% non-continuous), UL 1008 standard ampere ratings

Generated

For preliminary engineering use only — always verify results against project-specific standards and a qualified engineer's review before use in a real design.

System & load

kW
V
%

Transfer switch sizing

Total load current334.1 A
Continuous portion334.1 A
Non-continuous portion0.0 A
Minimum switch rating417.6 A
Recommended standard rating600 A