400A+ Transfer Switches

400A and larger transfer switches Above 400A the transfer switch is commercial equipment: service-entrance rated, often three-phase, and sized against available fault current. This collection carries 129 switches at 400A and above. Selection rules Service rating and fault current. The switch must carry the service and be rated for the available fault current at that…

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About 400A+ Transfer Switches

400A and larger transfer switches

Above 400A the transfer switch is commercial equipment: service-entrance rated, often three-phase, and sized against available fault current. This collection carries 129 switches at 400A and above.

Selection rules

  • Service rating and fault current. The switch must carry the service and be rated for the available fault current at that point - the engineer of record specifies this.
  • Open vs closed transition. Closed transition requires the generator and utility to be synchronised; it needs the right controller and is not a catalogue swap.
  • Three-phase considerations. Confirm voltage, phase and neutral arrangement; the generator and switch must match the service.
  • Enclosure and location. NEMA 1 indoors, 3R outdoors, 4X for washdown; confirm clearances and ventilation.

Installation and documentation

NEC Article 702 and local amendments apply. Expect the inspector to want the listing, the fault-current rating and the grounding/neutral arrangement documented. Send the service size, voltage/phase, generator model and single-line if you have one to the quote desk.