Electrical Codes and Standards Applicable to PV Installations
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The codes and standards affecting PV equipment and system installations are almost as varied as the equipment itself. The Canadian Standards Association (CSA), California Energy Commission (CEC), Institute of Electrical and Electronics Engineers (IEEE), International Code Council (ICC), International Electrotechnical Commission (IEC), National Fire Protection Association (NFPA), Underwriters Laboratories (UL) and countless other agencies all have their own opinion as to how PV system components should be manufactured and how PV systems should be installed. As a result, there is no unanimity regarding what equipment is considered safe for use and what constitutes proper installation.
While the manufacturer’s installation instructions generally take precedence over other requirements, many local or state jurisdictions have additional requirements beyond those found in the National Electrical Code. Furthermore, when a PV system is utility owned and operated, the installation is technically outside the scope of the NEC. But what exactly is a utility? This is a very important distinction because the NEC generally requires the use of equipment listed to UL standards. However, if a PV installation is not subject to the NEC, the use of equipment designed to meet other standards, such as those established by the IEC, may be permitted.
Since the standards to which PV equipment must conform vary by context, as do the applicable codes, it is incumbent on designers and installers to understand the regulatory context within which they are working. This regulatory context influences what equipment and installation practices are likely to be acceptable to the AHJ and the interconnected utility. Because there is no universal set of requirements, system designers and installers must be proactive about communicating with AHJs and utilities to streamline project permitting, inspection and commissioning.
Codes vs. Standards
According to the Merriam-Webster dictionary, a code can be either “a systematic statement of a body of law,” in particular one that is “given statutory force,” or “a system of principals or rules.” By comparison, the dictionary defines a standard as “something established by authority, custom, or general consent as a model or example.” While you may think of codes as mandatory, this is not always the case.
The NFPA has developed more than 300 codes and standards intended to “minimize the possibility and effects of fire and other risks.” As explained on the NFPA website (nfpa.org): “A code is a model, a set of rules that knowledgeable people recommend for others to follow. It is not a law, but can be adopted into law.” In other words, codes like the NEC become mandatory only after a governing body adopts them, making them enforceable by a legal jurisdiction in a particular area.
Most of the documents published by the NFPA are standards rather than codes. According to the NFPA: “A standard tends to be a more detailed elaboration, the nuts and bolts of meeting a code. One way of looking at the difference between codes and standards is that a code tells you what to do, and a standard tells you how to do it.” This basic distinction holds true for equipment standards, like UL 1703 or UL 1741, which essentially tell manufacturers how to construct flatplate PV modules or inverters, charge controllers, and combiner boxes, as well as how to test the equipment to ensure product safety.
Electrical Codes and Standards
The electrical codes and standards most likely to apply to PV installations are the National Electrical Code, the National Electrical Safety Code (NESC) and product standards. Most system designers and installers are quite familiar with the NEC and generally recognize applicable UL product safety standards. However, they may be less familiar with the NESC and equipment standards from organizations other than UL.
NFPA 70: NEC. The National Fire Protection Agency is the nonprofit fire prevention organization responsible for developing the NEC and other consensus codes and standards. Founded in 1896, the NFPA traces its origins to an 1895 movement in Boston that established standard pipe sizes for sprinkler systems—a standard that is now catalogued as NFPA 13.
The first edition of what is now known as the NEC or NFPA 70 was published in 1897 under the cumbersome title Rules and Requirements of the Underwriters’ Association of the Middle Department for the Installation of Wiring and Apparatus for Light, Heat and Power.