Installation is not the same as commissioning. A generator that has been set, connected, and fueled is not a generator that has been verified to perform when it is needed. Commissioning is the process of confirming that every system, from fuel delivery to transfer switching to control logic, works correctly under real operating conditions before the unit is declared ready for service.
This checklist covers what needs to be verified at each stage.
Pre-Startup Visual and Mechanical Checks
Before the generator is started for the first time at a new installation, a physical walkthrough of the unit and its connections should confirm the following.
- All shipping brackets and transport restraints have been removed
- Engine oil is filled to the correct level with the manufacturer-specified grade
- Coolant level is correct and the mixture ratio is appropriate for the installation climate
- Fuel supply is connected, valves are open, and the fuel tank or day tank is filled to operating level
- Battery bank is fully charged and connections are clean and tight
- All electrical connections between generator and transfer switch have been made per the wiring diagram
- Exhaust system is properly supported, routed, and terminated with no contact with combustible materials
- Air intake and ventilation openings are unobstructed
- Generator is properly grounded per NEC requirements for the installation type
Any item on this list that cannot be confirmed should be resolved before the first start attempt. Starting a generator with an oil, coolant, or fuel deficiency can cause immediate and expensive engine damage.
Initial Start and No-Load Verification
The first start is a controlled observation, not a transfer event. The unit should be brought up on manual start with no load connected, and the following parameters confirmed before any load is applied.
Engine parameters to verify at no-load startup:
- Oil pressure rises to normal operating range within the first few seconds of start
- Coolant temperature climbs to normal operating range and stabilizes
- No abnormal exhaust color — white smoke on cold start is normal briefly; persistent blue or black smoke is not
- No unusual mechanical noise, vibration, or fluid leaks
- Fuel consumption appears normal with no signs of fuel system leaks at connections
Electrical output at no load:
- Output voltage is at rated level across all phases
- Frequency is stable at 60 Hz
- Voltage is balanced across phases within acceptable tolerance
Allow the unit to run at no load until coolant temperature stabilizes before applying any electrical load. Rushing to load a cold engine accelerates wear and can mask developing problems that would appear clearly once the unit reaches operating temperature.
Transfer Switch Verification
The automatic transfer switch must be tested as a system, not just confirmed as wired. A transfer switch that is correctly installed but incorrectly programmed can fail to transfer, transfer at the wrong time, or retransfer before utility power has actually stabilized.
Transfer switch commissioning checks include:
- Confirm utility voltage sensing is reading correctly on all phases
- Test engine start signal by simulating a utility outage and confirm generator starts within the configured time delay
- Confirm transfer occurs after the generator reaches stable voltage and frequency
- Verify the connected load transfers cleanly with no abnormal voltage dip or equipment fault
- Simulate utility restoration and confirm retransfer delay operates as configured
- Confirm engine cooldown cycle runs before generator shuts down after retransfer
- Test manual transfer function and confirm it operates independently of automatic controls
Time delay settings should be documented at commissioning so they can be verified against configuration during future testing. NFPA 110 specifies maximum transfer time requirements for emergency and standby power systems in regulated applications. If the installation is subject to NFPA 110, confirm that the measured transfer time falls within the required threshold before signing off on the commissioning record.
Load Bank Test at Commissioning
The load bank test at commissioning serves a different purpose than the factory load test. A factory test confirms the generator performed correctly before it left the facility. A commissioning load bank test confirms the generator performs correctly in its installed configuration, on its actual fuel supply, with its actual cooling environment, connected to the real transfer switch and distribution system.
A complete commissioning load bank test should step through 25%, 50%, 75%, and 100% of rated output, holding each stage for a minimum of 15 minutes and the full-load stage for at least 30 minutes. Parameters to record at each stage include output voltage across all phases, output frequency, engine oil pressure, coolant temperature, and any alarm or fault conditions that appear during the test.
Voltage should remain within 5% of rated output at all load stages. Frequency should hold close to 60 Hz throughout. Any voltage sag, frequency drift, or parameter exceedance at rated load that was not present during factory testing points to a fuel supply restriction, cooling system issue, or electrical fault that needs to be resolved before the unit is placed in service. For a detailed look at what load bank test results should show and how to read them, the generator load bank testing overview covers the methodology and interpretation.
Control Panel and Remote Monitoring Verification
Modern industrial generators include control panels that monitor and log operating parameters, manage alarm conditions, and in many cases support remote monitoring through a network connection or building management system integration. Commissioning should confirm all of these functions are operating correctly before the unit goes live.
Control panel verification checklist:
- All fault and alarm conditions are correctly labeled and mapped to the right parameter
- Low oil pressure shutdown activates at the correct threshold
- High coolant temperature shutdown activates at the correct threshold
- Overcrank protection activates if the engine fails to start within the configured attempt period
- Remote monitoring connection is confirmed if the installation includes network monitoring
- Event log is cleared of any factory test data so the commissioning record starts clean
- All alarm notifications route to the correct personnel if remote alerting is configured
Any alarm or shutdown that cannot be triggered and verified during commissioning should be documented and scheduled for follow-up testing. A shutdown protection that has never been tested is a protection that cannot be relied on.
Documentation to Complete Before Declaring the Unit in Service
Commissioning generates a record that will be referenced throughout the service life of the generator. At minimum, the completed commissioning documentation should include the initial startup date and technician identification, no-load electrical output readings, load bank test results at each stage, transfer switch test results including measured transfer time, all control panel settings and time delay configurations, and a record of any deficiencies found and how they were resolved.
This documentation supports future NFPA 110 compliance testing, warranty claims, and maintenance planning. A generator without a commissioning record is a generator without a baseline, which makes every future service call harder to diagnose accurately.
What Turnkey Industries Provides Before Commissioning Begins
Commissioning a used industrial generator is easier when the unit arrives with documentation already in hand. Every generator sold through Turnkey Industries is load bank tested and inspected through a 22-point process before it leaves the facility, and buyers receive the resulting test data as part of the purchase. That documentation gives the commissioning technician a confirmed baseline for output voltage, frequency, and engine performance, so the commissioning load bank test is verifying installation performance, not discovering unit condition for the first time.
Buyers comparing available units by output level can filter current inventory at Shop by kW. The used industrial generators inventory includes inspection-backed units with pre-sale test documentation across a range of manufacturers and output classes. For questions about what documentation is available on a specific unit before purchase, contact the Turnkey Industries team directly.
