Acceptance Testing for New Data Center Builds: A Developer's Checklist
A new data center can pass every visual inspection and still fail the moment real power flows through it. Loose connections, improper torque, and incorrect wiring can hide behind a finished build, surfacing only under live conditions when developers feel pressure to hit go-live. Acceptance testing for a new data center build is a critical opportunity to catch these defects before they cause delays in your project.
This checklist covers the five electrical systems every developer should verify before energization, including switchgear, protective relays, grounding systems, transfer switches, and UPS. The final section explains why NETA-accredited testing matters.
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Switchgear
Switchgear is your data center's master electrical traffic controller. The equipment routes power from the utility source while protecting the distribution system. It also isolates faults before they cascade downstream.
ANSI/NETA ATS-2025 helps guide switchgear testing, including checks such as:
Test insulation resistance on all bus sections and cables.
Measure contact resistance and confirm it meets the manufacturer's tolerances.
Test contact timing and confirm it meets ANSI/NETA ATS acceptance limits.
Verify protective device settings against the approved coordination study.
Confirm labels, nameplates, and one-line diagram references are accurate.
Document all findings with as-found and as-left values.
Catching a defect here costs less than finding it under live load, where access requires switching orders and arc-flash personal protective equipment (PPE).
Protective Relays
Protective relays are your facility's trip wire. They detect fault conditions and isolate affected circuits before a problem spreads through the distribution system. A relay that looks correctly specified on paper can still fail in the field, since a single missed wire can defeat an otherwise well-designed protection system. ANSI/NETA ATS-2025 relay testing requires full functional verification under field conditions, not just a settings review.
Check the following before going live:
Verify relay settings against the approved protection coordination study.
Test trip paths end-to-end, from relay trip to breaker open, and confirm correct sequence and timing.
Test breaker failure logic and confirm it's operational.
Verify lockout relay (86) operation and reset.
Confirm current transformer (CT) and potential transformer (PT) polarity and ratio.
Document all test results with as-found and as-left conditions.
Grounding Systems
Grounding systems protect people and equipment by giving fault current a controlled path and limiting dangerous voltage differences. Grounding is often underestimated because it remains invisible during normal operations and only reveals problems when something else goes wrong. ANSI/NETA ATS-2025 requires grounding verification while the system is still de-energized and accessible.
A grounding system testing program should confirm the following before energization:
Test the earth electrode resistance and confirm that the results meet ANSI/NETA ATS requirements, manufacturer guidance, and project specifications.
Verify the continuity of the equipment grounding conductor at all connection points.
Inspect bonding connections at switchgear, transformers, UPS, and power distribution units (PDUs).
Confirm the ground grid's continuity across the entire facility.
Verify grounding at separately derived systems, such as generators and UPS bypass sources.
Document all results in the certified test report.
A grounding defect found after energization is tough to fix, since it may require partially shutting down a live facility, sometimes with the entire operation offline until the issue is located and corrected.
Automatic Transfer Switches (ATS)
The automatic transfer switch detects a utility power loss and initiates a transfer to the generator backup. A failed ATS means the load never transfers, leaving the UPS to carry the facility until its battery runs out.
The switch itself operates in milliseconds, but the full restoration sequence depends on generator startup, stabilization, transfer settings, and project specifications, so new data center electrical testing must confirm both.
Check that your ATS is operating correctly with these steps:
Test the automatic transfer operation under load, confirming the switch performs when needed.
Measure transfer time and confirm it meets project specifications.
Verify the generator start sequence, covering the start signal, crank, and stabilization.
Test the return-to-normal sequence and confirm re-transfer to the utility.
Test manual bypass operation.
Document all sequence timing and load data in the certified test report.
A failing ATS gives no warning during normal operations, since it's never called on until a real outage happens. This is why simulated load testing matters. According to Uptime Institute data, transfer switch failure causes 36% of power-related outages, second only to UPS failure.
Uninterruptible Power Supply (UPS)
The UPS bridges the gap between utility power loss and generator pickup, protecting active workloads and mission-critical infrastructure. UPS failure causes 42% of power-related outages, more than any other system. NETA acceptance testing requirements under ANSI/NETA ATS-2025 call for battery verification, load testing, and bypass confirmation.
Test the UPS using these steps:
Test battery capacity at the cell and string level against rated runtime.
Check load bank output under rated load, not standby or partial load.
Test the static bypass switch operation and confirm the transfer time.
Test maintenance bypass operation.
Record input and output voltage, current, and frequency measurements under load.
Verify alarm and monitoring systems, confirming fault conditions and remote monitoring integrations.
UPS systems remain the leading source of power-related failures despite most facilities carrying redundant capacity. Each of these five systems requires individual verification. A NETA-accredited firm performs the testing under ANSI/NETA ATS-2025.
Why NETA-Accredited Acceptance Testing Is the Industry Standard
NETA, the InterNational Electrical Testing Association, accredits firms at the organizational level in addition to certifying individual technicians. That means the firm itself must prove independence from the equipment manufacturer, the supplier, and the installation contractor. ANSI/NETA ATS-2025 specifies which field tests are required before energization and the thresholds each must meet.
This independence is structural, since a manufacturer- or contractor-affiliated testing team carries a conflict of interest that NETA-accredited firms are built to eliminate. NETA-accredited testing gives your team a verified baseline for future checks and developers a defensible record for due diligence.
Data Center Acceptance Testing Checklist
Use this checklist to confirm every system is ready before your facility goes live.
Switchgear: Confirm insulation and contact resistance meet manufacturer tolerances. Verify that settings match the coordination study, then document one-line diagram references and all findings.
Protective relays: Check trip paths function correctly from relay to breaker, lockout relay operation resets as designed, and CT and PT polarity check out.
Grounding systems: Confirm earth electrode resistance meets ANSI/NETA ATS requirements and your project specifications. Verify bonding continuity at every connection point, and include separately derived systems in the review.
Automatic transfer switches (ATS): Test that the switch transfers under load within specifications, the full restoration sequence stays on schedule, and return-to-normal sequencing works as designed.
UPS: Check battery capacity meets rated runtime at the cell and string level, load bank testing holds at rated output, and bypass and monitoring integrations perform as expected.
Commission Your Data Center Acceptance Testing with Confidence
Executing this checklist requires a testing partner with true independence from both the equipment and installation sides of the project.
Power Solutions Group is a NETA-accredited firm, so its technicians work for you, not the equipment manufacturer or the installation contractor. That independence is backed by technical, firsthand experience since 2006 and commissioning and startup services built for mission-critical facilities. Data center developers across the country, including those breaking ground in Virginia and Atlanta, can demonstrate that their systems met documented acceptance criteria before going live. Contact Power Solutions Group to schedule your data center acceptance testing and move toward go-live with confidence.
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