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Author(s): Jeff Sargent. Published on November 1, 2016.

How well does the NEC cover the pot industry?


In “Growing Pains,” the cover story in the September/October issue of NFPA Journal, associate editor Jesse Roman wrote about the safety issues, electrical among them, associated with the legal growing and processing of cannabis.

To get a better understanding of the electrical challenges faced by this industry—one that could be on the brink of significant growth as more states consider legalizing medicinal and recreational pot use—I recently visited Auburn, Maine, including Lifespring Microclimates, an Auburn-based firm specializing in the design of highly efficient grow facilities. Recent legislation allowing legal medical dispensaries has spurred a construction boom of these facilities throughout the state, and Auburn has experienced a surge of activity related to the medical marijuana industry. That may be just a hint of things to come, since Maine voters will consider a referendum question in November seeking to legalize recreational use.

The overriding question that I hoped to answer with my visit was whether there is anything associated with the electrical installations in these facilities that is not adequately covered by NFPA 70®, National Electrical Code® (NEC®). While the good news is that there does not appear to be anything unique to the grow facilities that is not covered by the current requirements of the NEC, there are aspects that bear watching.

A few key takeways:

It’s all about power. Most industrial cultivation of cannabis happens in indoor grow facilities where the conditions can be managed and monitored for maximum yield. That means a lot of grow lights, and a huge consumption of power—an important metric for growers is “grams per watt.” Power for the artificial lighting and the air-conditioning needed to maintain the proper growing environment is one of the largest costs associated with growing cannabis.

In some locations, though, the power demands of those facilities are burdening an electrical infrastructure that was not designed to accommodate such heavy loads, particularly where residential and light commercial buildings are repurposed as grow facilities without any upgrade to the electrical supply or distribution system. Additionally, utility infrastructure can also be undersized, as this level of usage was not anticipated, particularly in rural areas. According to Dan Thayer, P.E., owner of Lifespring Microclimates, the electrical load of the air-conditioning systems in modern grow facilities is similar to that of a data center.

Surprisingly, many growers are using old-school lighting technology, as there has been a reluctance to move from the proven technology of high-pressure sodium (HPS) lighting to a more energy-efficient method such as LEDs. Although LEDs have made huge inroads into the residential and commercial lighting markets, the availability of LED technology that would provide a light spectrum quality and operational durability similar to HPS has been limited, and some of the initial LED luminaires proved to be unreliable. The upside to LED technology is longer lamp life, less operational heat (which reduces air-conditioning costs), and the lack of concern over the violent eruption that occurs when HPS lamps are broken.

Electricity and extraction processes may create hazards. Another concern includes the potential explosive environment that is created in some solvent-based extraction processes, where flammable liquids such as acetone are used to separate THC from cannabis buds for use in edibles and other marijuana products. It certainly appears that some electrical area classification is prudent, but unfortunately this is not always done, nor are there any cannabis industry standards that provide area classification information. Safer extraction processes that employ carbon dioxide can double the costs of installation over solvent-based processes.

Product certification should be considered. Lighting control panels are being installed in many of these facilities, and product certification of these industrial control panels is not the norm. Now that electrical infrastructure is becoming more robust across the industry, adequate short-circuit current ratings for these control panels becomes more of a concern.

These are just some of the electrical issues that need to be considered as the cannabis industry matures. Rapid growth has sometimes meant that problems or unsafe conditions are only discovered as a result of a major malfunction or fire, but the fact is that these issues are not insurmountable, and safety and productivity are not mutually exclusive. Like other industries, the cannabis business will profit from facilities that are professionally designed, installed, inspected, and operated.

JEFFREY SARGENT is a regional electrical code specialist for NFPA.