Understanding the regulatory process for power installations
With many major capital projects in the public or private domain, regulatory issues must be addressed as early as possible in the design review and bid specification processes, and independent power installations are no exception (see Figure 1). The crux of the regulatory process is in determining compliance of the equipment, and in compliance of the overall installation to the appropriate codes and standards. The enforcement of the codes and standards described in this article is intended to mitigate the risks associated with fire, electric shock, energy, grid protection, life safety, mechanical hazards, explosion, and employee health and safety. Of course, this list is not all-inclusive. The generator construction and performance as well as the installation itself will come under scrutiny as part of the regulatory process.
Stakeholders and documentation
A key area often overlooked when kicking off a power installation project is the importance of identifying stakeholders (see Figure 2). It is essential these interested parties be determined early on, because the stakeholder matrix will be what defines-at least in part-the regulatory process and requirements. This matrix will vary somewhat with the facility or occupancy to which the power plant is connected, but it is reasonable to assume that the stakeholders will consist of the designers and specifying professionals, installers, owners, insurers, equipment manufacturers, major component vendors, and authorities having jurisdiction (AHJs).
The primary documents governing installation related to independent power generation are the National Electrical Code (NEC) and NFPA 37: Standard for the Installation and Use of Stationary Combustion Engines and Gas Turbines. The generating plant as a manufactured piece of equipment is covered by UL 2200: Standard for Safety for Stationary Engine Generator Assemblies. A number of other installation codes will also come into play, including NFPA 110: Standard for Emergency and Standby Power Systems, NFPA 99: Health Care Facilities Code, and NFPA 30: Flammable and Combustible Liquids Code. Additionally, it is possible that the National Electrical Safety Code (NESC, IEEE C2) will be invoked. This document provides guidance and requirements for the practical safeguarding of persons during the installation, operation, or maintenance of electrical generating plants and associated equipment. The NESC also covers electrical supply conductors and equipment, including structural considerations of electric generating plants. Although intended primarily for utilities, electric generating plants under the exclusive control of qualified persons authorized by a controlling or regulating entity such as an industrial complex or utility interactive system may also be subject to the rules of the NESC.
Field evaluation, independent testing
The regulatory process for a power installation will optimally require independent third-party involvement. This third party, generally a nationally recognized testing laboratory (NRTL), will conduct a compliance evaluation of the generator and auxiliary equipment before and during construction of the physical equipment. The presence of an NRTL mark is evidence the compliance evaluation has been conducted and the equipment has been determined to be in compliance with the appropriate standards (see Figure 3). It is important to note that the installation is still subject to inspection by AHJs and other stakeholders.
Alternatively, power generating equipment not subject to an independent assessment may still be eligible for field evaluation. If successful, this will result in the application of a field label indicating a minimum level of electrical safety compliance with the appropriate standards. On-site testing will be required for a field label and may be conducted in conjunction with any commissioning tests required by the owner or other stakeholders. A review of construction will also take place as part of a field evaluation. The introduction of a generating plant into a power installation without any independent evaluation may result in extensive modifications as well as real-time testing prior to approval. These activities would likely introduce delays in the commissioning of the power plant. Typical issues that may require corrective action include:
- Unlisted or undocumented major components
- Lack of proper internal bonding or grounding
- Improper output circuit protection
- Unimpeded access to uninsulated live parts
- Unsuitability for the environment
- Inability to effectively ground equipment
- Missing guards on moving parts and high-temperature parts.
Implicit with either a listing or a field evaluation is the responsibility of the manufacturer to have control over the design and manufacturing process, as well as component and vendor selection. The compliance evaluation will require the NRTL to conduct a complete design review of the generator and auxiliary equipment. This review entails a clause-by-clause comparison of the requirements in the appropriate standards with the observed construction of the equipment, as well as review of installation instructions. Critical components are identified and they will be required to be listed or recognized, or undergo special investigations to ensure their suitability for the application. Any disparities or noncompliances are communicated to the manufacturer and corrective actions must be taken. Importantly, the certification organization is only allowed to report the findings and not the actual corrective actions. Therefore, it is not uncommon for a consultant to be brought in at this stage to assist with corrective actions and project completion. The product standards also define the required testing needed for the manufacturer to claim compliance. A listed product is subject to routine production-line testing, which would reduce or eliminate any verification testing that would be required for a field evaluation.
The guidelines for electrical and mechanical construction of electrical generating equipment operating at 600 V or less are provided by UL 2200. Additional IEEE and UL standards may be applied to installations generating at voltages in excess of 600 V. However, many of the basic requirements will be conceptually and practically very similar. These requirements are summarized below as guidance for manufacturers, designers, installers, and users.
- Enclosures: protection from electric shock
- Environmental: protection of components from anticipated ambient conditions, such as water in the form of rain, snow, or ice; falling or windborne dust; or oil mist
- Access to major components
- >Controls: accessibility, functionality, and identification
- Corrosion resistance
- Robustness: resistance to vibration and impact.
- Protection of wiring
- Internal wiring and proper cable management practices
- Electrical spacings
- Insulation selection and coordination
- Bonding of internal parts
- Field wiring provisions.
- Disconnecting devices
- Protective devices (fuses, circuit breakers, and limit controls)
- Industrial control equipment.
- Fuel systems and components (covered in more detail by NFPA 37)
- Fuel confinement
- Pressure considerations
- Component and materials compatibility with fuels
- Fuel control
Generally, the prime mover for electrical generating equipment will be powered by some type of fossil fuel, such as diesel, natural gas, or liquefied petroleum gas. The Standard for the Installation and Use of Stationary Combustion Engines and Gas Turbines is referenced in UL 2200 and is used to augment the coverage provided in the mechanical requirements section of UL 2200. The guidance in NFPA 37 includes construction as well as installation requirements. Notably, the design of the equipment must be able to accommodate the proper installation in accordance with the appropriate codes such as NFPA 37 and the NEC. The following sections highlight important elements of NFPA 37, and refer to installation as well as actual generator construction.
General requirements for engines
- Air supply and ventilation
- Foundations and structural considerations
- Outdoor location
- Engine wiring
- Engines located in hazardous locations
- Rooms in which engines are located.
Gaseous fuel supplies
More prescriptive requirements for gas trains are provided. These gas trains may be provided by the power plant manufacturer, the installer, or a combination. The gas train refers to the combination of gas conveyance, control, and isolation devices through which the gaseous fuel passes. Installation codes include:
- NFPA 54: National Fuel Gas Code
- NFPA 58: Liquefied Petroleum Gas Code
- ANSI/ASME B31.3: Process Piping, as applicable.
Liquid fuel supplies
- The use of liquid fuels implies provisions for fuel storage that is either integral or in proximity to the prime mover. General guidance for fuel tanks may be found in NFPA 30 and various UL or API standards.
- Prescriptive requirements for fuel conveyance and flow control, including piping, valves, and fittings, are covered in NFPA 37. Again, these components may be furnished by the power plant manufacturer or the installer.
- Fuel heating, vent piping, and filling are also covered by NFPA 37.
- Specific requirements are cited for reciprocating engine and combustion gas turbine lubricating oil reservoirs and pumping systems.
- Details for explosion venting, oil heating, and alarms and controls are also given in NFPA 37.
- The design of the exhaust system shall incorporate materials that are capable of withstanding the temperatures, exhaust gas content, and vibration associated with the operation of the prime mover.
- The manufacturer of the prime mover is to provide proper termination means for the installation of the remainder of the exhaust system.
Controls and instrumentation
- Prescriptive requirements for protective devices for reciprocating engines include engine overspeed, high coolant or cylinder temperature, and lubricating oil pressure and temperature. Additional requirements may apply.
- NFPA 37 defines a large number of protective and control functions and permissives for combustion gas turbines.
UL 2200 requires that starting equipment shall be designed and constructed in accordance with NFPA 110. Critical considerations include:
- An electric starter or a stored energy source may be used to start the prime mover. Stored energy systems may include, but are not limited to, hydraulic, pneumatic, or rotational.
- The prime movers shall have provisions for charging, or maintaining a charge on any starting batteries or control batteries.
- Stored energy starting systems are to be able to complete two complete cranking cycles.
What to watch for
The highest likelihood for regulatory concerns and enforcement involves Articles 700, 701, 702, 705, and 708 of the NEC. These articles cover emergency systems, legally required standby systems, optional standby systems, interconnected electric power production sources, and critical operations power systems (COPS), respectively. The AHJ is required to conduct or to witness tests of the complete system at completion of the installation for emergency and legally required standby systems. Periodic testing schedules and maintenance schedules for critical components are also to be established and approved by the AHJ. Minimum on-site fuel requirements for the prime movers also apply to these systems, as well as COPS. External fuel and power supplies are not considered to be reliable or predictable for these systems.
All equipment for grid interface systems covered by NEC Article 705 is to be approved, including converters and transfer switches. COPS introduce the concept of risk assessment, which will entail engagement of all of the critical component suppliers including the generator manufacturers.
Role of the consulting, specifying engineer
Overall, planning for the regulatory process is an important part of power plant design and equipment specification. Consulting and specifying engineers should be aware of the various codes and standards covering both the equipment and the installation. Such preparation enables CSEs to provide proper ordering specifications for the equipment manufacturers, and design the site to accommodate the equipment and the functionalities required by the end user. If the equipment is not listed, the manufacturer and the third party to be involved in the field evaluation should be engaged by the CSE prior to the completion of the project.
The interest of all stakeholders is best served by addressing the regulatory concerns at the onset of a major project and not as a second thought. Taking such a proactive and informed approach should lead to a smoother and a timelier commissioning of the on-site generating plant, and better overall success.
Tom Buchal is a senior consultant at Intertek. He has more than 30 years of certification experience in the industrial, HVAC, and energy-related fields. He has also authored several industry publications, and is a regular speaker at industry and standards development events.