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Automatic transfer switch (ATS) maintenance checklists

Automatic transfer switch (ATS) maintenance checklists for the quarterly and annual rounds: 2 free lists, 28 items and 23 photo requirements, each item naming what to look for and the photo evidence it needs. Work is commonly verified against NEC (NFPA 70) and NFPA 110; the edition in force is the AHJ's call on each project.

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The automatic transfer switch (ATS) rounds

Automatic transfer switch (ATS) QuarterlyAutomatic transfer switch (ATS) quarterly maintenance checklistController status, settings, enclosure and a no-load transfer test confirmed on the quarterly round14 items11 photosAutomatic transfer switch (ATS) AnnualAutomatic transfer switch (ATS) annual maintenance checklistOn-load transfer test, connection heat check and contact inspection on the annual service14 items12 photos

Where each walk sits in the schedule

  1. 01quarterly

    Automatic transfer switch (ATS) quarterly maintenance checklist

    Every quarter, tied to the generator exercise since the transfer switch is what proves the generator actually picks up the load.

    Run by: The electrical or facilities tech on the quarterly round, coordinated with whoever runs the generator so the building isn't dropped.

  2. 02annual

    Automatic transfer switch (ATS) annual maintenance checklist

    Once a year, scheduled when the served loads can ride through a real transfer and back, and when the switch can be opened de-energized afterward.

    Run by: The electrical service tech on the annual, with a plan for the momentary outage the on-load test creates.

What most often fails on an automatic transfer switch (ATS)

  • Generator exercised in no-load mode while the transfer switch itself never actually transfers, so a stuck mechanism goes unfound until an outage.
  • Controller sitting in a fault or maintenance-lockout state for weeks because nobody reads the display.
  • Engine-start and transfer time delays bumped during a service call and never returned to the commissioned values.
  • On-load transfer skipped because it means a real interruption, so the switch is only ever proven with no load behind it.
  • Loose or hot lug on the line or load side found only after it has burned the insulation, because connections are never scanned under load.
  • Contacts never inspected, so pitting and burning build up until a transfer arcs or fails to make.

Verified against

Families only, never clause numbers. Adoption varies by jurisdiction; confirm the edition your authority having jurisdiction enforces before you run a walk against it.

Common questions

5 answers

Which automatic transfer switch (ATS) maintenance rounds do these checklists cover?
Automatic transfer switch (ATS) quarterly maintenance checklist (quarterly): Every quarter, tied to the generator exercise since the transfer switch is what proves the generator actually picks up the load. Automatic transfer switch (ATS) annual maintenance checklist (annual): Once a year, scheduled when the served loads can ride through a real transfer and back, and when the switch can be opened de-energized afterward.
Who runs the automatic transfer switch (ATS) maintenance round?
The electrical or facilities tech on the quarterly round, coordinated with whoever runs the generator so the building isn't dropped. The electrical service tech on the annual, with a plan for the momentary outage the on-load test creates.
What most often fails on an automatic transfer switch (ATS)?
Generator exercised in no-load mode while the transfer switch itself never actually transfers, so a stuck mechanism goes unfound until an outage. Controller sitting in a fault or maintenance-lockout state for weeks because nobody reads the display. Engine-start and transfer time delays bumped during a service call and never returned to the commissioned values. On-load transfer skipped because it means a real interruption, so the switch is only ever proven with no load behind it.
Which standards is automatic transfer switch (ATS) work verified against?
NEC (NFPA 70), published by the National Fire Protection Association; NFPA 110, published by the National Fire Protection Association. Adoption varies by jurisdiction. Confirm the edition your authority having jurisdiction enforces before you run a walk against it.
Can I run these checklists in RTI?
Yes. Start a free RTI workspace and load any of the 2 lists (28 items in total). The Photo Gate holds the submit button until every mandatory item is answered and its photos are attached, and approved inspections roll into a branded turnover package with a tamper evident audit trail.

Run these lists with the Photo Gate.

Tag one area, scan it, and the submit stays locked until the photos exist.

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