Commissioning is the structured testing that verifies installed systems work as designed. Closeout transfers the facility from contractor to owner with documentation, training, and warranty in place. The bridge from \"design\" to \"operating.\"
Project Phases — Where Closeout + Commissioning Live
RFIs, submittals, change orders, site visits, punch lists
Commissioning (Cx)
3-6 months (overlaps with end of construction)
Witness factory acceptance tests + on-site testing + final acceptance
Closeout
1-3 months
As-builts, O&M manuals, warranties, training, final invoice
Operations / Warranty
1-year warranty period
Warranty walk-through at 11 months
Commissioning — The Full Picture
Commissioning (Cx) is the structured process of verifying that installed systems work as designed. For Atlas DC1, electrical commissioning runs from FAT (Factory Acceptance Test) of major equipment through 5-Level testing to final integrated systems test (IST).
Cx Level
Name
What's tested
When
Level 1
FAT (Factory Acceptance Test)
Each major equipment piece tested at manufacturer's factory before shipment
Before delivery
Level 2
Site Receipt + Storage
Equipment received undamaged; stored properly
At delivery
Level 3
Component-Level Static Test
Insulation tests, mechanical operation, calibration of individual devices (no power)
Pre-energization
Level 4
Subsystem Functional Test
Each subsystem energized + tested independently (UPS, gen, ATS individually)
System energization
Level 5
Integrated Systems Test (IST)
Full facility tested under simulated failure scenarios — utility loss, gen failure, UPS failure, fault scenarios
Pre-occupancy / pre-handover
NETA Acceptance Testing
InterNational Electrical Testing Association (NETA) publishes the standard test procedures for electrical equipment. Used at Cx Level 3 (component static testing) by independent electrical testing firms.
NETA standard
Scope
NETA ATS (Acceptance Testing Specifications)
Tests on NEW equipment before energization
NETA MTS (Maintenance Testing Specifications)
Tests on EXISTING equipment for periodic maintenance
NETA STD (Standard for Electrical Power Equipment Maintenance)
Maintenance frequency + procedures
NETA ETT (Electrical Testing Technician)
Certification standards for the testing personnel
What's Tested at Each Cx Level — Atlas DC1 Examples
Level 3 — Component Tests (NETA ATS)
Equipment
NETA tests required
Cables (medium voltage)
Insulation resistance + DC withstand (hipot at 80% factory test) + partial discharge if cable > 1000 ft
Cables (low voltage)
Insulation resistance only
Transformers (TX-A, TX-B)
Insulation resistance + winding ratio (TTR) + DC winding resistance + power factor (Doble) test + oil testing (dielectric breakdown, DGA)
Switchgear (12.47 kV MV SWGR)
Operation test (open/close), insulation resistance, contact resistance, primary current injection of CTs, secondary trip testing of relays
Circuit breakers
Insulation resistance, contact resistance, time-current calibration (primary current injection)
UPS units
Vendor commissioning (battery acceptance, transfer testing, harmonic verification)
Generators
Insulation resistance, governor calibration, voltage regulator setup, 4-hr load bank test, parallel testing if applicable
ATSs
Manual + automatic transfer cycles, time delay verification, load testing
Grounding system
Ground resistance test (3-point fall-of-potential), continuity verification of grounding electrode system
Protective relays
Setting verification + secondary current injection at each pickup level
Surge arrestors
Insulation resistance, leakage current
Level 5 — Integrated System Test (Atlas DC1)
Full facility tested under simulated failure scenarios. Owner/operator + Cx authority + design engineer all witness.
Test scenario
What's verified
Pass criteria
Utility loss → genset start (Side A)
ATS-A senses loss, signals GEN-A start, gen reaches voltage + frequency, ATS transfers
Total time < 12 sec; UPS rides through; IT load uninterrupted
Utility loss → both sides simultaneously
Both ATSs transfer to gens within target time
Both gens sync with their respective UPS within 15 sec
Genset failure on Side A while running
UPS-A1 detects gen output loss, transitions to battery
Begin Level 5 IST: simulated utility loss → ATS transfers → gen runs → IT load (load bank) ride-through verified
Owner + Cx + Engineer + Vendor
17:00
Run all IST scenarios from Cx test plan
Same
20:00
IST complete. Full day's results documented.
—
21:00
Daily debrief; punch any issues; plan tomorrow's IT load bank ramp testing
—
"First customer rack" gets installed weeks later after Cx is fully signed off. There's no rush — this day is about verifying the facility CAN power critical IT load. Actual IT load comes when the customer is ready.
If You See THIS, Think THAT
If you see…
Think / use…
"Cx" or "commissioning"
Structured testing process — Levels 1-5
"FAT" (Factory Acceptance Test)
Cx Level 1 — at manufacturer's factory before shipment
"NETA ATS"
Independent electrical testing at Cx Level 3
"IST" (Integrated Systems Test)
Cx Level 5 — full facility tested under failure scenarios
"Punch list"
List of construction deficiencies to be corrected before final acceptance
"As-built drawings" / "Record drawings"
Final drawings showing what was actually installed (vs design IFC)
"Substantial completion"
Date when facility is fit for intended use; warranty period starts
"Final completion"
All punch list resolved; final invoice releasable
"O&M manual"
Operating + maintenance manual for installed equipment
"Lien release"
Subcontractor waives right to file lien against owner property; required for final payment
"Warranty walkthrough"
Inspection at 11 months — final chance to get warranty work done
"EPO test"
Emergency Power Off — drops all ITE + HVAC per NEC 645.10. Must be tested at Cx Level 5.
"Hot cutover"
Energizing while old system is still live — used in retrofit projects, riskier than greenfield