Author(s): Jesse Roman. Published on May 2, 2016.

Decentralization Revolution

As electrical generation and transmission becomes less utility-centric, the NEC keeps pace with a host of new provisions focused on emerging technologies.


FOR OVER A CENTURY, electrical generation and distribution in the United States was mostly tidy and consolidated. Big utility-owned power plants on the outskirts of urban centers generated electricity and fed it into a network of transmission lines that distributed it far and wide.

In this century, that centralized model has begun to change. Improved technology and plummeting costs have driven a surge in privately owned wind and solar power generation as more businesses and individuals view energy self-sufficiency as economical and strategically smart. This hodgepodge of new electrical generation is an ever-growing and important piece of the nation’s energy pie, supplementing power from traditional utilities.

NFPA Conference Session
NFPA Conference & Expo, Las Vegas, June 13-16, 2016

NFPA 70-2017, National Electrical Code: Changes (Panel 1 of 3)
Monday, June 13, 9:30 AM to 10:30 AM

Michael Johnston, National Electrical Contractors Association (NECA); Keith Lofland, International Association of Electrical Inspectors (IAEI)

Energy Storage Systems—Installation and Operation Safety Requirements
Monday, June 13, 11:00 AM to 12:30 PM

Jack Lyons, National Electrical Manufacturers Association

NFPA 70-2017, National Electrical Code (NEC): New Articles for Energy Storage Systems, DC Microgrids, and Stand-Alone Systems
Tuesday, June 14, 8:00 AM to 9:00 AM

John Kovacik, UL

NFPA 70-2017, National Electrical Code: Changes (Panel 2 of 3)
Tuesday, June 14, 9:30 AM to 10:30 AM

Michael Johnston, NECA; Keith Lofland, IAEI

Microgrid System Deployment
Tuesday, June 14, 11:00 AM to 12:30 PM

Chad Kennedy, Schneider Electric

PV + Storage: The Path of Rapid Shutdown and ES Safety Gaps
Tuesday, June 14, 11:00 AM to 12:30 PM

Matt Paiss, International Association of Fire Fighters; Paul Rogers, Fire Department of New York

NFPA 70E-2018, Standard for Electrical Safety in the Workplace: Proposed Changes
Tuesday, June 14, 3:30 PM to 4:30 PM

David Dini, UL; Paul Dobrowsky, Innovative Technology Services

Electrical Installation of PV Systems per NFPA 70, National Electrical Code (NEC): A Comparison of the 2014 and 2017 editions
Tuesday, June 14, 3:30 PM to 5:00 PM

Mark Ode, UL

NFPA 70-2017, National Electrical Code: Changes (Panel 3 of 3)
Wednesday, June 15, 8:00 AM to 9:00 AM

Michael Johnston, NECA; Keith Lofland, IAEI

NFPA 70-2017, National Electrical Code (NEC), Articles 690 and 691: Solar Photovoltaic (PV) Systems
Wednesday, June 15, 9:30 AM to 11:00 AM

Bill Brooks, Brooks Engineering; James Rogers, Town of Oak Bluffs

“Ten years ago nobody would've imagined the amount of infrastructure we have built out in this space,” said Bill Burke, division manager, electrical engineering, at NFPA.

The changing landscape has caused electrical experts to reimagine the future of the electrical grid, and has been one of the main drivers for three of the most important proposed additions to the 2017 National Electrical Code® (NEC®). More and larger consumer-owned power generation has caused the NEC’s code-making panels to consider systems and circumstances they never had previously.

Since its inception in 1896, the NEC’s scope has been limited to electrical considerations on the customer side of the meter—that is, the code’s rules do not apply to utility-owned-and-operated generation and distribution equipment. Back when big utilities controlled virtually all generation and distribution, the line of demarcation was relatively simple: the NEC regulated the generation and transmission of electrical power, and NEC rules took over at the point where the electricity entered the customer’s property, typically a building.

“In the NEC we call that the service point, where the utility’s responsibility ends and where we begin,” says Jeff Sargent, a regional NEC code specialist at NFPA.

“But that line of demarcation is dynamic and it is moving. As energy decentralization has pushed the utility’s responsibility farther away from the owner’s electrical system, the NEC has had to address different and higher voltage systems.”

Three of the five new proposed articles in the 2017 NEC are a direct consequence of this trend: Article 691, “Large-Scale Photovoltaic”; Article 712, “Direct-Current Micro-grids”; and Article 706, “Energy Storage Systems.”

(Very) large-scale PV

Photovoltaic panels, or PV, are hardly new, first appearing in the NEC in 1984. Those systems generated little power and adoption was scarce.

The large-scale systems covered under the proposed Article 691 are another matter entirely, says Mark Earley, NFPA’s chief electrical engineer. By definition, large-scale PV arrays are systems that produce at least 5 megawatts (MW) of power, roughly enough to power 800 average U.S. homes. But the systems can be much larger than that, according to Earley. During the summer of 2014, Earley and a few members of the NEC technical committee travelled to the Sonoran Desert in California to visit a solar farm there called Desert Sunlight. When it’s completed, the array will have an estimated 6 million panels and produce 550 MW of power, enough to power 160,000 homes, according to the facility’s website.

“The scale was really rather surprising,” Earley says. “Driving down the center, it stretches for something like five miles in each direction, and all you can see to the horizon in both directions is this sea of PV.”

Aside from its magnitude, the Desert Sunlight facility is also unique in that it’s a private investment venture and is not owned by a utility. The energy generated at the facility is fed into the electric grid and sold to utilities. It is essentially a privately owned power plant and falls within the scope of the NEC. The problem, though, according to Sargent, is that the NEC’s “current PV requirements don’t adequately cover installations of this magnitude.”

That’s largely because solar arrays topping 5 MW did not even exist until 2007, and the truly massive arrays exceeding 100 MW have all been built since 2012, according to the Solar Energies Industry Association (SEIA). There are now nine solar arrays in the U.S. larger than 100 MW, all of them in California and Arizona, according to SEIA.

In addition to setting some basic requirements for installation, the NEC’s proposed large-scale PV article actually eases or removes some of the traditional PV requirements found in the code. Despite the size of these systems, there are aspects that make them safer than a typical home array, Earley says. Nearly all these big arrays, for instance, are located in isolated areas far from communities, making some NEC PV requirements moot.

“Most of these arrays are in fenced off areas so the only people with access are PV professionals,” Earley says. “There are a few requirements you don’t need because these panels are not mounted on a building, such as rapid shutdown. But because these facilities are usually in fenced-in areas, there are some requirements for grounding of fences, and things like that.”

Direct-current microgrid

Direct-current (DC) microgrids are another example of electrical infrastructure that has traditionally been utility owned, but is migrating to the consumer side. Essentially independent power distribution networks, microgrids are becoming popular around the world among certain kinds of large facilities and campuses as a means to increase energy efficiency, reduce costs, and maintain critical business continuity.

Independence from the grid is appealing as a hedge against fluctuating energy prices and power interruptions that threaten business. But for certain large companies, private DC energy generation and distribution can also save hundreds of thousands of dollars per year.

Ever since George Westinghouse prevailed over Thomas Edison in the electric current wars of the late 19th century, utilities have delivered electricity as alternating current (AC). However, computer equipment, electronics, LED lighting, communications equipment, and other critical systems run on DC power, meaning electricity from the grid must be converted to DC before those devices can use it. That conversion, however, results in the loss of some electricity, which, in the case of a big tech or telecommunications company operating huge data centers, can add up to significant sums.

NEC by the Numbers

The clear benefits have led to hundreds of DC microgrids to be deployed around the world, at data centers, airports, college campuses, and more. “This is like creating a little utility at the building,” Sargent says.

All that activity caused the NEC technical committee to take notice. The current NEC covers basic requirements for wiring, overcurrent protection, and grounding, but does “not cover all of the issues involved when multiple DC sources and DC loads are interconnected, justifying the need for a new NEC Article,” the DC Task Group of the NEC technical correlating committee wrote in its substantiation for the creation of the new chapter. The task group wrote that it sees this new article “as an important first step, and a place-holder for future requirements in this rapidly developing area.”

Energy storage systems

As detailed in the January/February 2016 NFPA Journal cover story, “Power to Spare”, energy storage systems (ESS) are swiftly transforming the energy landscape. Because of the enormous flexibility the systems provide, adoption is expected to expand rapidly across multiple sectors, and even into the residential consumer market. ESS enables the storage of renewable energy for use when the wind isn’t blowing and the sun isn’t shining. ESS also allows consumers to buy and store electricity from the grid when prices are low (such as at night) and use it when demand and prices rise. Hospitals, data centers, airports, and other facilities with critical operations can use battery power to ensure business continuity in an outage. For utilities, storing large amounts of energy in batteries means extra energy is available to carry the electricity load during infrequent spikes in demand, eliminating the need to build more power plants.

The NEC has had some requirements for batteries since the 1897 edition, but nothing as comprehensive as the proposed NEC Article 706, Earley says. The proposed article has “a lot of detail” for a new facet of the code, he says, and includes rules on equipment, installation of single and multiple ESS, disconnection and shutdown, safety labeling, and more. The article covers electrochemical storage batteries, flow batteries, capacitors, and kinetic energy devices such as flywheels and compressed air.

As comprehensive as this first attempt is, Sargent admits it’s just a start, and that ESS is a significant new category still in its infancy. “This is our first shot at it—as these systems become more mainstream, the safety rules will evolve much like photovoltaic,” Sargent says. “It’s hard to anticipate or create in a test lab what is going to happen in the real world, but the technology isn’t waiting for the codes and standards. The technology is going to move forward.”

Safety first

New and changing technology isn’t the only driver of change in the NEC. As in all editions, there was a healthy amount of input and revision. All told, the NEC’s code-making panels received more than 4,000 public inputs on the code, which is on the high side, Earley says. Among those changes that made it into the document are new requirements designed to improve safety for electrical workers and first responders. Here’s a brief rundown of a few of the proposed changes:

    External shutoff for first responders: This new requirement, which would go into effect in 2020, would require all new one- and two-family residential structures to have external switches to cut the power to a residence. Currently the NEC requires a means to disconnect electrical service, but does not specify where the switch should be. The fire service has long supported an external shutoff switch requirement to avoid having to enter a burning or flooded building to cut power if necessary. Typically, the fire service calls the utility company to disconnect service if needed, but in some rural areas that can take a half hour or more and in many situations time is of the essence.

“The new requirements will help us implement the safe work practices that 70E calls for—if we have a safe initial installation, it will help facilitate safe work practices,” Sargent says. “That’s how the two documents work together.”

One revision calls for more detailed labeling on equipment, such as the nominal voltage, incident energy, and the level of personal protection equipment needed. By giving maintenance workers specific information unique to that electrical system they will have a better sense of what precautions should be taken, Sargent says. “Right now, all we are requiring is a basic warning such as ‘Danger Arc Flash Hazard,’” he says.

Another revision designed to address worker safety would establish minimum front and side space clearances for installation of certain electrical equipment. The rule is meant to ensure that workers aren’t in danger when working in tight spaces packed with equipment, such as above a ceiling or in a crawl space.

“We want to avoid a situation where a worker has to get in that space and troubleshoot, or test the leads and meter, and can’t fully open enclosure doors, or has to work up against a grounded surface,” Sargent said.

In other changes, a new Article 425 addresses rules for industrial process heating equipment, such as electrode boilers, duct heaters, strip heaters, immersion heaters, and other approved fixed electrical equipment for commercial and industrial process heating. A new Article 710 gives specific rules for stand-alone energy systems that are not connected to the grid. Some of these stand-alone systems include PV systems, wind-powered systems, fuel cells, engine generators, and others. Finally, new rules were added regarding electrically powered pool lifts that provide accessibility to a pool or spa for people with disabilities.

The deadline for submitting notices of intent to make a motion on the NEC was April 29, as this issue of Journal was going to press. More information on the process for the 2017 edition of the NEC can be found at the NEC document information webpage.

JESSE ROMAN is associate editor for NFPA Journal. Top Illustration: Sarah Jones