Electrical Commissioning Checklist: Tests, Standards and Acceptance Values

A commissioning checklist is only useful if every item names the test, the governing standard and the value that constitutes a pass.

A list of test names is a reminder. A list with acceptance criteria and role assignments is a document an owner can enforce, and the difference shows up when a reading comes back marginal and nobody can say whether it passes.

The governing reference in North America is ANSI/NETA ATS, the Standard for Acceptance Testing Specifications for Electrical Power Equipment and Systems. The current edition, ANSI/NETA ATS-2025, was approved by the American National Standards Institute on 20 February 2025.

Electrical commissioning verifies all electrical systems and components, ensuring they operate safely and reliably under real-world conditions. At Prismecs we understand this step is especially vital for Power Generation, Renewable Energy, Oil and Gas, and Data Centers, where operational uptime and system integrity are non-negotiable.

This checklist sets out each stage, the standard that governs it, and the acceptance value where one is published.

Why You Need an Electrical Commissioning Checklist

An electrical commissioning checklist converts a set of intentions into a verifiable record, which is what distinguishes a commissioned system from an installed one.

It serves as a structured tool to evaluate all aspects of the electrical system. No details are missed, and no assumptions are made.

This checklist helps:

• Ensure safety compliance
• Detect installation errors
• Verify system performance
• Prevent equipment failures
• Maintain project timelines

Most importantly, it gives the confidence to proceed with energization, knowing that systems are tested and validated.

What makes a checklist enforceable

Three things, none of which a topic list has. An acceptance criterion for each test, so a result can be judged. A named standard, so the criterion has a source. And a role assignment, so it is clear who performs the test and who witnesses it.

ANSI/NETA ATS itself requires a determination of who shall perform preliminary low-voltage insulation-resistance, continuity and motor rotation tests, and notification of when equipment becomes available for acceptance testing. Those are project coordination obligations, not technical ones, and they are where most commissioning programmes lose time.

Key Elements of the Electrical Commissioning Checklist

Below is the recommended breakdown for a complete electrical commissioning procedure, covering the switchboard and main switch, final circuits and distribution boards.

The structure follows ANSI/NETA ATS, which organizes each equipment section identically: Visual and Mechanical Inspection, then Electrical Tests, then Test Values. That sequence is not arbitrary. A visual defect found before energization costs an inspection; the same defect found during a test costs equipment.

Which edition applies

ANSI/NETA ATS has been revised repeatedly, with editions published in 1991, 1995, 1999, 2003, 2007, 2009, 2013, 2017, 2021 and 2025.

The 2025 edition was approved as an American National Standard on 20 February 2025.

Name the edition in the specification. A programme written against a superseded edition drifts out of compliance without anything changing on site, and the acceptance values move between revisions.

Where this sits in the commissioning sequence

Electrical acceptance testing is pre-functional and functional work, feeding an integrated systems test that proves the whole plant together.

Outside North America

IEC 60364-6 governs verification of low-voltage installations, covering initial verification, the required testing sequence and periodic verification. The tests are broadly equivalent and the acceptance values and documentation requirements differ, so confirm which regime governs before writing the specification.

Documentation Review and Pre-Checks

Documentation review is the first checkpoint, and it is the one that determines whether the rest of the programme can proceed.

Before physical inspections, verify that all relevant documents are accurate and available.

Checklist to verify:

• Approved electrical drawings and schematics
• Manufacturer’s manuals and test certificates
• Safety compliance documentation
• As-built documentation and design modifications
• Operation and maintenance manuals

Documentation acts as the backbone of the commissioning process. Without it, field inspections cannot move confidently.

The inspection and test plan

An inspection and test plan, or ITP, lists every inspection and test, with the acceptance criterion, the governing standard, and who attends each one.

A hold point stops work until the nominated party attends and releases it. A witness point notifies them and allows work to continue if they do not attend. The distinction is contractual and it determines what the owner can enforce.

Mark the ITP before testing starts. Marking everything as a hold point is unworkable; marking nothing means attending at convenience rather than at the point of risk.

If documentation is missing

Do not proceed to energization. A manufacturer’s test certificate establishes the equipment’s as-shipped condition, and without it a marginal field result cannot be attributed to installation, transport or manufacture.

Record the gap formally rather than working around it, because the absence becomes the owner’s problem at handover.

Visual and Mechanical Inspection

Visual and mechanical inspection precedes every electrical test in the NETA sequence, because defects found here are cheap and defects found later are not.

Inspect all equipment and installations for quality and compliance. Look for physical damage, correct labelling and proper mounting.

Key areas to assess:

• Switchboard and main switch integrity
• Distribution board connections and clearances
• Circuit breaker alignment and identification
• Cabling, routing and insulation checks
• Grounding and bonding system verification

These checks ensure that installations are structurally sound and prepared for energization.

Labelling is a safety function

Circuit identification, panel directories and equipment labelling are not documentation tidiness. They determine whether a technician isolating a circuit during a fault isolates the right one.

Verify labelling against the as-built drawings rather than against the design drawings, because that is where the difference appears.

Safe working during commissioning

NFPA 70E governs electrical safety in the workplace, including the energized electrical work permit, the arc flash risk assessment and the lockout and tagout procedure.

Commissioning involves work on equipment transitioning between de-energized and energized states, which is precisely the condition NFPA 70E exists for. Confirm the safety programme, the permit process and the competency of the personnel before the first test.

Working Space and Facilities

Working space around electrical equipment is a code requirement with specified dimensions, not a matter of convenience.

NFPA 70, the National Electrical Code, Article 110.26 specifies minimum working space for equipment likely to require examination, adjustment, servicing or maintenance while energised. The required depth varies by nominal voltage to ground and by the condition of the facing surfaces, with greater depth required where exposed live parts or grounded surfaces are on the opposite side.

Article 110.26 also specifies minimum width, headroom, illumination, and the number and arrangement of entrances to working space for larger equipment.

Checklist to verify:

• Minimum clearance in front of panels and breakers
• Emergency exits and access routes
• Lighting and environmental conditions around electrical rooms
• Labels and signage visibility
• Proper working space prevents accidents and enables safe intervention during maintenance or emergencies.

If clearance is insufficient

It is a code non-compliance, not a snag. The remedies are relocating equipment, relocating what obstructs it, or in rare cases a formal variance from the authority having jurisdiction.

Identify it during design review rather than at commissioning, because by then the equipment is installed and the adjacent construction is complete.

Permitting

The authority having jurisdiction inspects against the code as adopted locally, and electrical sign-off is frequently a precondition for occupancy or energization. Confirm what the AHJ requires to witness before scheduling, because a test performed without the required witness may need repeating.

Testing of Circuit Breakers and Switchgear

Circuit breaker and switchgear testing is where acceptance values matter most, and ANSI/NETA ATS publishes them.

Tests include:

• Insulation resistance testing
• Trip function testing
• Mechanical operation checks
• Thermal imaging to detect hotspots
• Current injection tests

Ensure the circuit breaker ratings match the load characteristics and protection requirements of the system.

Insulation resistance acceptance values

Insulation resistance is measured by applying a DC test voltage and measuring the resulting current, expressed in megohms. NETA Table 100.1 gives minimum values for apparatus other than rotating machinery, with the test voltage rising with equipment rating.

Minimum insulation resistance of control wiring shall not be less than two megohms.

Rotating machinery uses a separate table, NETA Table 100.11, with values based on IEEE Std 43-2013 and read at one minute, corrected to 40°C.

Temperature correction is not optional

Insulation resistance varies substantially with temperature, so a reading taken at ambient and compared to a 40°C table without correction is not a valid comparison.

Corrected resistance equals measured resistance multiplied by the applicable temperature factor from NETA Table 100.14.2. A reading of 2 megohms on oil-immersed insulation at 20°C, with a factor of 0.40, corrects to 0.8 megohms at 40°C, which is a materially different result.

Record the test temperature alongside every reading. Without it the result cannot be corrected and cannot be compared to anything later.

Polarization index

Polarization index is the ten-minute insulation resistance reading divided by the one-minute reading, taken during the same continuous test. It indicates whether insulation is clean and dry or contaminated and moist.

ANSI/NETA ATS requires a polarization index not less than 1.0 for transformers and similar apparatus, and greater than 2.0 for motors and generators.

Under IEEE 43-2013 interpretation, a PI between 1.0 and 2.0 is questionable, 2.0 to 4.0 is good, and above 4.0 is excellent. The dielectric absorption ratio, taken at 60 seconds over 30 seconds, is the faster equivalent, with below 1.25 questionable and above 1.6 excellent.

Sequencing: the rule that protects equipment

Dielectric withstand voltage tests shall not proceed until insulation resistance levels are raised above minimum values.

Applying a high-potential test to insulation that has already failed its resistance test can destroy the equipment. If no evidence of distress or insulation failure is observed by the end of the voltage application, the specimen is considered to have passed.

If insulation resistance is low

Investigate before retesting at higher voltage. The usual causes are moisture ingress, surface contamination on terminations, and connected equipment that was not isolated for the test.

Dry the equipment, clean the terminations, confirm the isolation, and retest. Do not proceed to dielectric withstand until the resistance passes.

Primary and secondary injection

Secondary injection tests the protective relay by injecting a signal at the relay inputs, proving the relay’s settings and logic. Primary injection drives current through the complete circuit including the current transformer and the breaker, proving the whole protection chain end to end.

Secondary injection is faster and cheaper. Primary injection is the only method that proves the CT ratio, polarity and wiring are correct, which is where protection schemes most commonly fail.

Specify which is required per device rather than accepting whichever the contractor prefers.

Switchboard and Main Switch Testing

The switchboard and main switch are the system’s control centre, and their reliability affects the entire downstream network.

The commissioning checklist includes:

• Torque checks on all terminal connections
• Functional testing of metering and monitoring equipment
• Voltage phase rotation verification
• Load balancing and current distribution
• Emergency shut-off test functionality

Check that the main switch operates smoothly and disconnects all downstream loads as expected.

The bolted connection acceptance criterion

• Torque to the manufacturer’s published specification, and then verify electrically. ANSI/NETA ATS gives the criterion that makes the verification meaningful.
• Compare bolted connection resistance values to values of similar connections, and investigate any value deviating from similar connections by more than 50 percent of the lowest value.
• That single threshold turns a torque check into a pass or fail. A high-resistance joint that passed a torque wrench will fail this comparison, and it is the joint that later shows as a hotspot on thermal imaging.
• For rotating machinery, investigate phase-to-phase stator resistance values deviating by more than five percent.

If a connection fails

Do not simply re-torque. A connection showing elevated resistance after correct torque indicates a surface condition, a damaged conductor or an incompatible material pairing between aluminium and copper.

Break the joint, inspect, clean or replace, and retest. Re-torquing a contaminated joint resets the symptom without fixing the cause.

Final Circuits Testing

Final circuits connect the distribution system to end devices such as lighting, motors and sockets, and each must be tested before energization.

Checklist to verify:

• Polarity and continuity tests
• Voltage measurements at final outlets
• Load test with simulated equipment
• Short-circuit and earth fault loop impedance
• Functionality of residual current devices and circuit protection
• Each final circuit must be verified to ensure safety and proper load distribution.

Earth fault loop impedance

Earth fault loop impedance is the total impedance of the path a fault current follows from the point of fault back to the source. It determines how much current flows during an earth fault, and therefore how fast the protective device disconnects.

The acceptance value is derived from the protective device’s required disconnection time, not chosen independently. A measured impedance above the maximum for that device means the device will not disconnect fast enough, regardless of its rating.

State the maximum permitted impedance per circuit on the checklist, calculated from the device and the required disconnection time. Without it the measured value cannot be judged.

Residual current device testing

A residual current device, or RCD, disconnects when it detects an imbalance between line and neutral current, indicating current leaking to earth. Testing verifies the trip time at rated residual current and at a multiple of it, against the maximum times for the device type.

Test the device in place using the installation’s own wiring. A device that passes on the bench and fails in situ is indicating a wiring fault, which is exactly what the test exists to find.

Distribution Board Testing

Distribution boards control and distribute power within the facility, and each requires verification of balance, labelling and operational readiness.

Testing includes:

• Tightness of all terminals
• Phase-to-phase and phase-to-ground voltage
• Circuit labelling and directory verification
• Busbar and neutral integrity
• Tripping characteristics of breakers
• Full testing under simulated conditions uncovers hidden faults or imbalances.

Verifying tripping characteristics

A breaker’s time current characteristic defines how quickly it operates at a given multiple of rated current. Verification confirms the device performs within the manufacturer’s published curve.

The acceptance band is the manufacturer’s curve, so the curve must be available before the test. Testing without it produces a number with nothing to compare it to.

If a breaker fails its trip test

Replace rather than adjust, unless the device is designed for field adjustment and the deviation is within its adjustment range. A thermal-magnetic breaker outside its curve has a mechanical or thermal defect that adjustment does not address.

Record the serial number and the result. A pattern of failures within one batch is a supply problem rather than an installation problem.

Functional Performance Testing

Functional performance testing proves the system behaves correctly as a system, which component testing cannot establish.

Functional testing includes:

• Power-up procedures
• Load transfer scenarios
• Emergency stop and reset sequences
• Alarm system checks
• Integration with SCADA or control systems

This stage validates how the system performs in real conditions, and it is where commissioning moves from verifying parts to verifying behavior.

Load testing

Testing at design load requires load banks where the real load is not yet available. Resistive load banks draw real power at unity power factor; reactive load banks add the inductive component the real load will present.

A system tested on resistive load alone has not been tested at the power factor it will actually see, which matters for generators, UPS systems and transformers.

Alarm and sequence verification

Test every alarm by creating the condition that should raise it, not by forcing the signal. An alarm that annunciates when forced but not when the condition occurs has failed, and only the first method finds that.

Verify the sequence of operation against the written control philosophy, and record any discrepancy as a deficiency rather than correcting the document to match the behavior.

Coordination with Other Systems

In integrated facilities, electrical systems interface with HVAC, fire alarm, automation and standby power systems, and the interfaces are where commissioning most often finds problems.

Checklist to verify:

• Control signal integrity
• Power supply redundancy
• UPS and generator failover testing
• Communication between systems
• Interlocks and system responses

Proper coordination ensures seamless operation across all building or plant systems.

The standard that governs standby power

NFPA 110, the Standard for Emergency and Standby Power Systems, classifies systems by Type, Class and Level. Type defines the maximum permitted time between loss of normal power and the emergency power system accepting load.

The acceptance test measures against that classified time. A system that transfers slower than its Type permits fails regardless of whether it eventually transfers.

Confirm the Type classification in the design documents before testing, because the acceptance criterion comes from it.

If transfer fails

Establish whether the failure is in the sensing, the transfer mechanism or the generator start sequence, because all three present the same symptom.

Transfer testing is also where the negative tests belong: confirming that automatic transfer does not occur when the system is in bypass, which is a condition that must not trigger it.

Final Handover and Reporting

The commissioning report is the deliverable, and it becomes part of the facility’s permanent record.

What is included:

• Final commissioning checklist summary
• Punch list of any deficiencies
• Test results and calibration reports
• Sign-off sheets from engineers and supervisors
• Recommendations for operation and maintenance

This report supports regulatory compliance and forms the baseline for all future maintenance testing.

Why the baseline matters more than the pass

Acceptance test results become the reference for maintenance testing under ANSI/NETA MTS. A later reading is judged against the commissioning value as much as against the standard, because the trend reveals deterioration that a single value cannot.

Record actual values, not pass or fail. A report stating “satisfactory” has destroyed the baseline it was supposed to create.

Deficiencies and the punch list

Categorise deficiencies by whether they prevent energization, affect performance, or are cosmetic. The categorization is the negotiation, and it determines what releases payment.

Insurance and warranty

Insurers assess commissioning evidence when underwriting new electrical installations, and a documented acceptance test record is the strongest evidence available.

Equipment warranties frequently depend on correct commissioning and on energization within specified conditions. The test record protects the warranty position as well as the operation.

Ownership of records

Establish that the owner holds the test records, calibration certificates and sign-off sheets, in native format, with no restriction on providing them to a different operator or a purchaser.

Benefits of Using Prismecs’ Electrical Commissioning Checklist

A structured electrical commissioning checklist brings clarity and control to complex projects, and the benefit is measured in what it prevents.

• Reduced risk of costly failures
• Faster project completion with fewer delays
• Full code compliance and certification
• Improved safety for people and equipment
• Long-term operational reliability

What differs by sector

• Power generation commissioning centres on generator protection, synchronization and the relay scheme, with primary injection proving the complete protection chain.
• Data centre commissioning centres on redundancy and transfer, with the integrated systems test proving that the facility rides through a utility loss at design load.
• Renewable energy commissioning centres on inverter and grid interface compliance, where the connection requirements come from the grid code as well as from the electrical standards.
• Oil and gas commissioning adds hazardous area classification, where equipment certification and installation methods are verified alongside electrical performance.
• The checklist structure is constant. What changes is which tests carry hold points and which acceptance values are tightest.

At the Bottom Line

An electrical commissioning checklist is the mechanism that turns an installation into a verified system, and its value depends entirely on the criteria attached to it.

Every test on this checklist has an acceptance value. Insulation resistance against NETA Table 100.1, corrected for temperature. Polarization index against 1.0 for transformers and 2.0 for machines. Bolted connections against the 50 percent deviation threshold. Working clearance against NEC Article 110.26. Transfer time against the NFPA 110 Type classification.

A checklist without those values records that a test was performed. A checklist with them records whether it passed.

Ensuring Safety and Reliability

Thorough testing and verification establish that the electrical supply is safe to energise and reliable in service.

The safety case rests on three things: correct protection settings proven by injection testing, verified earthing and bonding, and working space that allows safe intervention. Each has a standard and a measurable criterion.

Verified protection coordination also reduces the consequence of a fault. A correctly coordinated system clears a fault at the nearest upstream device rather than tripping a larger section, which limits both the outage and the arc flash energy.

Reducing Risks and Downtime

Commissioning reduces downtime by finding defects at the point where they are cheapest to correct.

A high-resistance connection found during acceptance testing costs a joint remake. The same connection found in service costs an unplanned outage, probable equipment damage and the investigation that follows.

The recorded test values also shorten future diagnosis. A fault investigated against a known commissioning baseline is resolved faster than one investigated against nothing.

Trust Prismecs for Seamless Electrical Commissioning

Prismecs delivers electrical commissioning for industrial energy facilities, covering pre-commissioning checks, acceptance testing, functional testing and handover documentation.

Delivered project scope includes eight TM2500 dual-fuel units totaling 260 MW at Birr, Switzerland, online in six months with a new 220 kV interconnection and engineered noise controls on a compact site; four TM2500 units totaling 110 MW at Duqm, Oman, kept grid-ready with resident O&M crews, CMMS and parts support; an LM2500XPRESS plant at Miaoli, Taiwan delivered in ten months; and an LM6000 fleet decommissioned in Norway, transported and recommissioned at a new site.

The Norway relocation is the relevant reference for this subject. Decommissioning an operating fleet, transporting it and recommissioning it at a new site requires the full acceptance testing sequence performed on equipment with service history rather than on new equipment with factory certificates.

Comprehensive Electrical Commissioning Services

Prismecs performs pre-commissioning, relay calibration, transformer energization, functional testing, transfer switch commissioning and final system validation.

Relay calibration is the verification and setting of protective relays against the coordination study, proving by secondary and where specified primary injection that each device operates at the intended current and time. It is the activity that determines whether a protection scheme works, and it is where a commissioning contractor is distinguished from an installer.

Transformer energization is the controlled first energization of a transformer following insulation resistance, turns ratio, winding resistance and polarity verification. Inrush current on first energisation can reach many times rated current, which is why the sequence and the protection settings are confirmed beforehand.

Transfer switch commissioning proves the automatic transfer and retransfer sequences against the NFPA 110 Type classification, including the negative tests that confirm transfer does not occur in conditions where it must not.

Tailored Solutions with Transparent Reporting

Commissioning scope is defined by the equipment, the governing standards and the role the commissioning party holds, and all three should be written down before mobilization.

Capability spans I&C services for installation, commissioning, controls and SCADA support, EPC services for project delivery, owner’s engineering for independent witnessing and acceptance, O&M services for the operating phase, and technology and consulting for assessment. Delivered work is on the projects page.

One boundary worth stating. The party performing a test and the party witnessing and accepting it should not be the same. Prismecs takes the commissioning delivery role or the owner’s witnessing role on a given project, not both.

Apply this checklist’s criteria to any proposal, including ours. Ask which ANSI/NETA ATS edition the scope is written against. Ask which tests are hold points and which are witness points. Ask whether actual values or pass or fail statements will be recorded. Ask who holds the test records at handover.

To discuss electrical commissioning scope, acceptance testing or witness arrangements, send your equipment list and voltage levels, the governing standard and edition, your target energization date and whether you require independent witnessing to sales@prismecs.com or call +1 (888) 774-7632.

Frequently Asked Questions

What standard governs electrical acceptance testing?

ANSI/NETA ATS, the Standard for Acceptance Testing Specifications for Electrical Power Equipment and Systems, with the current edition ANSI/NETA ATS-2025 approved by the American National Standards Institute on 20 February 2025. It specifies field tests and inspections to assess suitability for initial energization and final acceptance, structured as Visual and Mechanical Inspection, Electrical Tests, then Test Values for each equipment type.

What insulation resistance value is acceptable?

NETA Table 100.1 gives minimums for apparatus other than rotating machinery: 25 megohms for 250 V equipment tested at 500 V DC, 100 megohms for 600 V equipment tested at 1,000 V DC, 1,000 megohms for 5,000 V equipment tested at 2,500 V DC, and 5,000 megohms for 15,000 V equipment. Control wiring must not be less than two megohms. Rotating machinery uses Table 100.11, based on IEEE Std 43-2013.

Why must insulation resistance readings be temperature corrected?

Because insulation resistance varies substantially with temperature, so a reading taken at ambient and compared to a 40°C table is not a valid comparison. Corrected resistance equals measured resistance multiplied by the factor from NETA Table 100.14.2. A 2 megohm reading on oil-immersed insulation at 20°C, with a factor of 0.40, corrects to 0.8 megohms at 40°C. Record the test temperature with every reading.

What is the polarization index and what value passes?

The ten-minute insulation resistance reading is divided by the one-minute reading from the same continuous test, indicating whether insulation is clean and dry or contaminated and moist. ANSI/NETA ATS requires not less than 1.0 for transformers and similar apparatus, and greater than 2.0 for motors and generators. Under IEEE 43-2013, 1.0 to 2.0 is questionable, 2.0 to 4.0 good, above 4.0 excellent.

When can a dielectric withstand test be performed?

Only after insulation resistance has been raised above minimum values. ANSI/NETA ATS states that dielectric withstand voltage tests shall not proceed until insulation-resistance levels are above minimum, because applying a high-potential test to insulation that has already failed can destroy the equipment. If no evidence of distress or insulation failure is observed by the end of voltage application, the specimen has passed.

How do you verify a bolted connection electrically?

By comparing connection resistance values to similar connections, and investigating any value deviating by more than 50 percent of the lowest value. That threshold turns a torque check into a pass or fail, because a high-resistance joint that passed a torque wrench will fail this comparison. For rotating machinery, investigate phase-to-phase stator resistance values deviating by more than five percent.

What is the difference between primary and secondary injection?

Secondary injection applies a test signal at the relay inputs, proving the relay’s settings and logic. Primary injection drives current through the complete circuit including the current transformer and the breaker, proving the whole protection chain end to end. Primary injection is the only method that proves CT ratio, polarity and wiring are correct, which is where protection schemes most commonly fail.

What working clearance does the code require?

NFPA 70, the National Electrical Code, Article 110.26 specifies minimum working space for equipment likely to require examination, adjustment, servicing or maintenance while energised. Required depth varies by nominal voltage to ground and by the condition of facing surfaces, with greater depth where exposed live parts or grounded surfaces face the working position. The article also specifies width, headroom, illumination and entrance requirements.

What governs standby power transfer testing?

NFPA 110, the Standard for Emergency and Standby Power Systems, which classifies systems by Type, Class and Level. Type defines the maximum permitted time between loss of normal power and the emergency system accepting load, and the acceptance test measures against that classified time. Confirm the Type classification in the design documents before testing, because the acceptance criterion derives from it.

What is earth fault loop impedance and how is it judged?

The total impedance of the path a fault current follows from the point of fault back to the source, determining how much current flows during an earth fault and therefore how fast the protective device disconnects. The acceptance value derives from the device’s required disconnection time rather than being chosen independently. State the maximum permitted impedance per circuit on the checklist, calculated from the device.

What is the difference between a hold point and a witness point?

A hold point stops work until the nominated party attends and releases it, so work cannot proceed without that release. A witness point notifies the nominated party and allows work to continue if they do not attend. The distinction is contractual and determines what the owner can enforce. Mark the inspection and test plan before testing begins rather than negotiating during it.

Should the commissioning report record pass or fail, or actual values?

Actual values. Acceptance test results become the reference baseline for maintenance testing under ANSI/NETA MTS, where a later reading is judged against the commissioning value as much as against the standard, because the trend reveals deterioration a single value cannot. A report stating “satisfactory” has destroyed the baseline it was supposed to create.

Which ANSI/NETA ATS edition should be specified?

Name the edition explicitly. ANSI/NETA ATS has been revised in 1991, 1995, 1999, 2003, 2007, 2009, 2013, 2017, 2021 and 2025, and acceptance values move between revisions. A commissioning programme written against a superseded edition drifts out of compliance without anything changing on site, which makes edition tracking a specification requirement rather than an administrative detail.

What applies outside North America?

IEC 60364-6 governs verification of low-voltage electrical installations, covering initial verification, the required testing sequence and periodic verification. The tests are broadly equivalent to the NETA sequence, while the acceptance values, documentation requirements and certification arrangements differ. Confirm which regime governs before writing the specification, because the two are not interchangeable.

Tags: Electrical Commissioning NETA ATS Acceptance Testing Insulation Resistance Commissioning Checklist