Electrical System Commissioning - Don’t You (Forget About Me)
Updated: Jul 21, 2022
As you walk on by, Will you call my name? Or will you walk away…
Breakfast Club soundtrack references aside, electrical system commissioning commonly takes a backseat to mechanical system commissioning in many non-data center projects. If you’re a facility manager, operations manager, or owner with responsibility for the successful operation of your facility, as much as you want reliability from HVAC or process systems, you’ll want it even more from your facility’s electrical power system.
Building commissioning leads to long-term safe, healthy, and reliable facilities that operate efficiently. Beyond just Code and sustainability certification requirements, hands-on, technical, and effective commissioning generates significant value for the owner, and offers benefits to designers, contractors, occupants, managers, and operations and maintenance (O&M) staff. For electrical systems, commissioning leads to high Availability, low Mean Time Between Failures (MTBF), and low risk of a critical loss of power, that is, a loss of electrical power that poses a threat to the three critical Ps: product, property, and people.
Commissioning has traditionally been focused on HVAC systems. Commissioning originated in the early 1980s in response to a large increase in HVAC construction litigation from asbestos exposure to duct construction standards to conditioning equipment failures. Commissioning was the result of owners seeking other means to gain assurance that they were receiving systems compliant with the design intent and with the performance characteristics and quality specified.
HVAC systems get most of the quality assurance focus due to their complexity, multiple trade coordination requirements, effect on energy use and utility costs, maintenance requirements, and longevity concerns. In addition, an HVAC system that has not been balanced, tuned and under control quicky becomes a point of occupant contention. End users have different opinions on the qualities of air delivered to the spaces (too hot, too cold, too stuffy, too breezy, too dry etc.) Electrical on the other hand is much more prescriptive and out of sight/out of mind. Unlike space temperature control, I have not heard a user state that they feel their 120v service should be reset down to 118v for better comfort or up to 122v for better efficiency (although maybe you have).
While the end user for electrical is equipment and not people, electrical systems should have the same amount, if not more, focus as mechanical or plumbing. It is estimated that roughly 70% of early power system failures have been linked to design, installation, or startup deficiencies. The increasing complexity of electrical systems and the growing intolerance for unplanned downtime prompted the development of the ANSI/NETA standards to expand the building commissioning scope and further enhance system evaluation more thoroughly than acceptance testing alone.
What uptime do you expect from your electrical system? Most would say, or assume, 100%. However, even a facility with 99.8% electrical availability sounds great until you realize that 0.2% is 24 hours, one full day of downtime or three 8 hour working days of unavailability. For nearly every facility today, this lost time would be costly.
To protect against any unplanned downtime there are many electrical commissioning tasks that need to be completed to ensure the proper design, installation and long-term safety and reliability of electrical systems. Some of the tasks and questions that should be asked are outlined below:
As with all commissioned systems, the first step is to understand the owner’s expectations. The CxA must ensure answers to owner project requirement and basis of design questions are asked and responses are collected. Questions such as: Do we have legally required Life Safety loads on Generator power? What spaces and equipment are planned to be on emergency, standby or uninterruptable power? Are there any power quality requirements or concerns? How much spare capacity is required? Where is power required for equipment maintenance? Will spaces be sub metered? What electrical assets and points should be mapped to the Building Management System? What are the operation requirements of the lighting controls system?
The biggest impact a CxA can have is in the design phase. Catching issues early, verifying clear instructions to the contractors and providing recommendations pay untold dividends down the road. If the design phase is missed, the quality train has already left the station. The CxA must ensure Specification and Project Requirements directed to the Electrical Contractor are clear, concise and understood.
Is the Electrical Contractor responsible for providing a Power System Study (Short Circuit, Coordination Study, Arc Flash Study)? Is NETA testing required and is the testing scope clearly defined and understood? Is Generator Load Bank testing required and are acceptance testing requirements defined (above and beyond NFPA 110?)
The submittal review process provides important system of checks and balances during the construction phase of a project. The purpose is to ensure that equipment and systems intended to be installed conforms to the design intent depicted in the contract documents and meets the expectations of the owner. The CxA, along with the engineer of record and owner reviews the Division 26 submittals including Common Work Results, Power Conductors and Cables, Transformers, Panelboards, Lighting Controls, ATS and Generators for conformance to the construction documents. This is not only a provides a quality control checkpoint but also familiarity with the electrical systems for development of checklists and testing protocols.
SITE WALKS AND INSPECTIONS:
The purpose of the site walk inspection is to begin to identify the key areas which require checking, and to make sure all electrical systems adhere to appropriate standards and specifications. As always, an electrical inspection is normally needed to ensure the safety of others. However, it is important to make sure that your own safety is not put at risk in performing the inspection. Verify all wiring methods and cable assemblies, type and insulation. Check pull
boxes for the appropriate conductor fill. Verify planned grounding and bonding. The NETA testing agency owes the project team a deliverable specifying all NETA tests performed and identifying any findings/failures that should be addressed.
For installation references the electrical industry has installation construction standards, such as the National Electrical Installation Standards, developed by the National Electrical Contractors Association (NECA). These standards cover selected electrical equipment, wiring methods, and installation standards for safety, which are contained in the National Fire Prevention Association’s National Electrical Code (NEC), ANSI/NFPA 70. ANSI/NFPA 70 codifies the installation of electrical equipment and systems within buildings.
PRE-FUNCTIONAL CHECKLIST EXECUTION:
Pre-functional checklists are necessary to ensure that the equipment and systems are ready for operation and testing. It ensures that functional testing (in-depth system checkout) may proceed without unnecessary delays. Documentation required for Electrical PFC verification includes the final Power System Study (Short circuit, Coordination, Arc Flash study). The Short Circuit Study identifies equipment not properly rated for the available fault current in that part of the electrical system. The CxA needs the Coordination Study to ensure satisfactory electrical coordination is achieved throughout the system and circuit breaker trip settings are set to their final values. Finally, the CxA needs the Final Arc Flash study to verify incident energy levels are within the owner’s PPE requirements and the correct Arc Flash Labels are installed on Panel covers.
Included in the checklist is a walkdown of the single line and Final Panel Schedules. This is always done following the energization and typically the last item for the electrical contractor.
Other items that may be required per the spec prior to functional testing is primary injection testing for the circuit breakers, megger testing of the wiring insulation, ground bonding test, and contact resistance tests, HiPot testing etc.
It is a good idea to utilize job progress site walks as an opportunity to start filling out Electrical PFC’s. Most checklists require panel dead-fronts to be removed following panel wiring complete to verify interior of panels. Other prefunctional checklists outside of distribution include electrical equipment a generator inspection, ATS sequence and settings review (including time delays), lighting and lighting controls and UPS inspections.
FUNCTIONAL TESTING EXECUTION:
Most of the electrical distribution commissioning occurs during pre-functional checks (prior to permanent power). Various electrical systems require permanent power to prove conformance with project requirements including lighting, Electric metering, ATSs, Generators, UPSs, and Paralleling Switchgear
Lighting control devices and control systems must be tested, to ensure that control hardware and software are calibrated, adjusted, programmed, and in proper working condition in accordance with the construction documents and manufacturer’s installation instructions. These devices include occupancy sensors, time switches, programmable schedule controls, and photosensors.
Each ATS start/stop wiring circuity needs to be verified by isolating Normal Power to each ATS and ensuring the ATS start signal commands the generator on and the ATS transfers to Emergency Power. Programmable transfer time delays and ATS priorities are tested to the emergency power system Sequence of Operations.
The Generator Start-Up Technician will typically test through the required NFPA 110 monitoring points as per the Generator functional test. The Start-up technician should be aware of all the points they need to test and come prepared (Potentiometer, Multi-meter, PQM, Megger).
UPS testing requires the manufacturer start-up rep to support testing activities. Typically, there will be a need to transition the UPS from Inverter to Static Bypass, Maintenance Bypass, back to inverter power, and verify kirk key interlocking scheme, simulate faults and alarms.
To operate the building in accordance with the design intent, the building staff must be trained on the installed equipment and systems. The suppliers and contractors will normally conduct the training with the training being observed by the commissioning team. The electrical training plans and records are retained and updated for use in later training.
Electrical Commissioning activities that were not performed, such as IR scanning, due to insufficient load on the panels initial certificate of occupancy may be conducted during post occupancy.
At the completion of the project the final commissioning report is assembled and provided to the owner and others. This report includes all documentation produced and collected, including all electrical installation, startup, inspection, verification, functional and performance test forms and reports, and the final issue and resolution log.
Electrical commissioning is an extremely broad term that covers many different areas of electrical review, inspection, testing and verification. Electrical system commissioning ensures that all different aspects of the electrical system are in proper working order, it ensures safe work environment free of unnecessary risks, it ensures that an employer complies sufficiently with regulatory standards and has a safe work environments, and it ensures the reliability of the electrical system.
GMC Cx focuses just as much on electrical systems as we do on mechanical or plumbing. While the M and P systems enjoy the all the attention, the electrical system is the backbone of any building. Without it, nothing works. There is a high cost of unreliability. U.S. commercial and industrial businesses reported that 40% had experienced a power outage costing more than $50,000 during the last year, with 2% reporting losses over $2 million. In the more complex, more electric focused ‘New Electric World’, businesses face the risk of more unplanned downtime, highly inefficient electrical operations, and more frequent equipment failures. These can all lead to higher OPEX spending and, in some cases, major financial losses. For these reasons, more focus must now be placed on testing and commissioning to help ensure reliable electric power.