Generator and ATS Maintenance Report Template

Example: Before winter, a property manager books maintenance for a small commercial building's standby generator. The technician's invoice says “ran generator, checked battery.” It does not identify which automatic transfer switches were tested, whether building loads transferred, or what remained untested because a tenant could not accept an interruption.

That leaves the next service company with a record of a visit and little evidence of what the system actually did. A useful generator and automatic transfer switch (ATS) maintenance report connects each asset, authorized task, observation, and result to the operating condition left at handoff.

Use the outline below alongside the equipment-specific maintenance and test procedures. It helps organize the record; the qualified person responsible for the system must establish the work and acceptance criteria.

Identify the generator, every ATS, and the governing requirements

Start the electrical work order with the site, visit date, technician, generator asset ID, manufacturer, model, serial number, fuel, rated output, and hour-meter reading. Identify the controller and each ATS separately, including its rating, transition arrangement, location, and served loads or distribution reference.

One generator can serve several transfer switches. Give each switch its own result. “Generator tested” does not show which transfer paths or loads were tested.

Carry forward the approved load schedule and system boundaries from the generator and transfer-switch quote. Record changes since installation, such as additional equipment or a revised load-management arrangement, for qualified review.

List the applicable manufacturer manuals and revisions, facility maintenance plan, project criteria, and adopted requirements. Where NFPA 110 applies, identify the applicable edition and system classification from the approved records. NFPA's 2025 edition overview covers the power source, transfer equipment, controls, and related equipment. Its publication does not establish the edition or obligations governing this particular site.

An optional standby installation and a regulated life-safety system need different scope decisions. Resolve an unknown classification before making a compliance claim.

Agree on the interruption and the permitted work

Record the authorized tasks, outage window, affected occupants or processes, site contact, notifications, and any required temporary power or impairment arrangements. Include the approved test procedure and the conditions that require stopping or deferring it.

Describe whether the visit includes external observations, isolated internal maintenance, operational testing, building-load transfer, load-bank testing, or some combination. Access to a generator enclosure is not authorization to interrupt tenant power.

Use a job hazard analysis for the actual work and energy sources. For covered general-industry electrical maintenance, OSHA 29 CFR 1910.333 generally requires exposed live parts to be deenergized before work, subject to its stated exceptions, with applicable lockout/tagging and verification. It specifically rejects control devices and interlocks as the sole means of deenergizing circuits. Reference the employer's applicable procedure and identify the utility, generator, battery/control supplies, and other energy sources it must address. A customer signature or controller setting does not replace that procedure.

If the approved interruption cannot occur, record exactly which test was deferred, why, who was informed, and the next action. Keep completed inspection findings separate from the untested function.

Keep inspection findings and maintenance traceable

Use the electrical inspection report for condition findings, with photographs tied to equipment IDs and locations. A compact record can cover these fields without printing generic pass limits:

PNNL's standby-generator O&M guidance supports logging maintenance, run hours, operating parameters, and trends, while placing manufacturer recommendations ahead of its example checklist. Cummins' maintenance guidance likewise calls for following the operator's manual and keeping maintenance and operating-hour records. Use the schedule for the exact equipment and service conditions.

For battery results, preserve the measurement type and units, battery details, relevant temperature, and comparison basis. Resting voltage, conductance, and a load-test result describe different measurements. A blank, a zero, and “not tested” must remain distinguishable.

For outdoor equipment, document observed water entry or deterioration and the qualified response. ASCO's water-damage guidance, August 2019, explains that water can affect transfer-switch operability, reliability, and service life. A note saying “cabinet dried” does not establish an acceptable operating condition.

State what each test demonstrated

In the general service report, name the test method and its boundaries. An engine exercise without transferred load, a facility-load transfer, and a load-bank test produce different evidence. A load bank connected at the generator does not, by itself, demonstrate that every ATS transferred its building loads.

PNNL's ATS O&M guidance, published July 2021, describes the switch's source sensing, generator-start command, source qualification, and load-transfer functions. Preserve evidence of the functions actually tested, together with the manufacturer's applicable procedure.

For an authorized transfer test, record the initiating event, initial operating state, ATS ID, connected loads, and observation points. Where timing is required, distinguish engine start, acceptable generator output, and power availability at the required load point. Name the timing method and any limits in clock resolution or event-log synchronization.

Cummins' February 2019 NFPA 110 Time to Readiness FAQ explains Type 10 performance in terms of power delivered to the load within 10 seconds. Engine cranking time alone does not demonstrate that result. Confirm the required start and end events against the governing edition and approved site procedure; do not apply Type 10 to every standby installation.

For a load test, retain the applied-load basis, actual measured load, duration, voltage, frequency, applicable phase measurements, operating readings, alarms, and native logs required by the procedure. Identify whether the load was building load, a load bank, or both. Record interruptions and deviations rather than treating planned duration as completed duration. Keep each measurement's units, instrument ID, measurement point, and time, with the instrument's applicable calibration or verification record.

Do not copy one universal coolant temperature, battery threshold, loading schedule, or transfer delay onto every report. Put the actual criterion and its source beside the result.

A test-record block to reuse

Attach a separate block for each asset and test to the service report. Adapt the fields to the approved procedure; this is a record outline, not instructions for performing the test.

TEST RECORD — report ___ / date and time ___
Generator ID ___ / ATS ID, if applicable ___
Test method, procedure and revision: ___
Initial state, sources and connected loads: ___
Start/end events, actual duration and timing method: ___
Measurements, units, instruments and log references: ___
Acceptance criteria and source sections: ___
Result: pass / fail / not tested / inconclusive — explanation ___
Defects, corrective work and retest references: ___
Final operating state, restrictions and notifications: ___
Technician ___ / follow-up owner and due date ___

Close defects and record the state left behind

Each defect needs an asset, evidence reference, consequence, action, responsible person, and target date or escalation. The electrical inspection reporting guide explains how to connect observations with service recommendations. Preserve the original result alongside any correction and retest.

Illustrative closeout: Generator G-1 ran during the approved visit. ATS-1 transferred and retransferred under the listed test conditions. ATS-2's transfer test was deferred because its interruption was not authorized. The report should state that ATS-2's transfer function remains unverified, identify the responsible contact, and record the arrangements for the deferred test.

Price additional planned work through an electrical estimate, or use an authorized change order where it changes the existing assignment. For urgent findings, follow the site's escalation and protective-action procedures; the after-hours electrical authorization guide helps define the separately authorized response.

At handoff, document source and switch positions, generator control mode, temporary settings, remaining alarms, restored guards and covers, and the actual operating disposition under the approved procedure. Record any restriction, isolation, or unresolved impairment. Do not clear an unresolved fault merely to produce a clean display or restore automatic operation contrary to the required disposition.

Use the completion sign-off to acknowledge delivery of the report, attachments, restrictions, and open actions. Keep receipt of the findings separate from the qualified technical conclusion. Set the next maintenance or deferred-test date from the applicable plan, with an identified owner.

Sources reviewed October 24, 2026. The linked O&M guides and manufacturer explanations support the reporting approach; the exact equipment instructions and applicable site requirements determine the work.