NFPA Journal

Energy Conscious
An overview of the proposed 2011 edition of the NEC, where a number of new provisions address renewable-energy technology including photovoltaic cells and wind turbines

NFPA Journal®, May/June 2010 

By Michael Johnston

There’s a lot of interest at the moment around the expansion of renewable energy sources, and it’s easy to see why. According to the U.S. Energy Information Administration (EIA), renewable-generated electricity, including sources such as wind and solar, will account for almost 16 percent of total U.S. electricity generation in 2030, up from about 9 percent in 2007. That growth, the EIA says, will be driven mainly by the extension of federal tax credits and the new loan guarantee program in the February 2009 American Recovery and Reinvestment Act. Meanwhile, EIA projects renewable energy’s share of total worldwide electricity generation will increase slightly between now and 2030, and will be the second largest source of energy for electricity production after coal.

To keep pace, a number of important proposed revisions, as well as new information, related to solar photovoltaic (PV) systems, fuel cell systems, and wind electrical systems have been incorporated into the 2011 edition of NFPA 70®, National Electrical Code®. In some cases, as with PV and fuel cells, the changes build on important provisions that have been part of the NEC for years. In other cases, the provisions are new; the 2011 edition of the NEC will be the first to address wind electrical power systems. In all cases, the changes to the new NEC reflect the evolving safety requirements of consumers, technicians, and emergency responders.

Here comes the sun
Article 690 of the NEC provides the rules for PV systems and has existed in the document since the 1987 edition. For the 2011 edition of the NEC, Article 690 has been revised to address evolving safety concerns related to PV system installations.

One significant revision deals with routing PV source and output conductors. A new Section 690.4(E) requires that these circuits be routed along a building’s structural members, such as beams, rafters, trusses, and columns, where the location of the structural members is easily determined by observation. Where the circuits are embedded or concealed in building finishes such as laminate and membrane roofing, they must be clearly marked that they contain PV wiring. The reason for the change is related to electrical safety concerns expressed by firefighters and emergency responders. PV systems will continue to produce power even though the service disconnect is opened. This new marking requirement will increase safety not only for service personnel, but for these emergency responders as well.

Another key revision is a new rule in 690.4(G) requiring that PV systems with multiple inverters remote from one another have a directory in accordance with 705.10 at each PV system dc disconnecting means. These directories would identify the locations of all ac and dc PV system disconnecting means in the building. This disconnecting means identification is an improvement in safety for those working on PV systems. Similarly, a new Section 690.11 will require listed dc arc-fault circuit interrupter protection for PV system source or output circuits that penetrate a building and operate at 80 volts or greater. This new technology will automatically disconnect a source circuit if an arcing fault is detected.

An important new change in Section 690.4(E) addresses qualifications of those installing equipment and wiring for photovoltaic systems. This revision now clearly indicates that all equipment and wiring related to solar photovoltaic technology be installed only by qualified persons.

Substantiation provided in the proposal and comment stages indicated that the increased efforts and incentives to install these systems have drawn many people into the PV business. The concerns are that contractors and installers engaged in this work have the necessary training and qualifications in the electrical field. PV systems produce electrical power and are often interconnected to the utility service on a building or to other structures served by that power. This is not a job for a handyman, and these systems are far more than plug-and-play. This revision is consistent with similar new requirements accepted in other areas of the NEC that address renewable electrical energy sources. The new national requirement parallels similar laws being passed at the state and local levels.  
   
Changes for fuel cell systems
Article 692, which covers fuel cell systems, was incorporated into the NEC in the 2002 edition. According to the NEC, a fuel cell system is a complete aggregate of equipment used to convert chemical fuel—such as natural gas—into usable electricity. A fuel cell system typically consists of a reformer, stack, power inverter, and auxiliary equipment.

There are two significant revisions to the NEC’s rules for fuel cell systems. A new Section 692.4(C) requires that fuel systems, and all associated interconnections and wiring, be installed only by qualified persons. As with PV, fuel cell technology requires far more than a handyman’s level of knowledge or training. Elsewhere, Sections 692.61, 692.64, and 692.65 address output circuit characteristics, unbalanced interconnections, and utility-interactive point of connections, respectively. These three sections have been revised to delete the contained requirements and refer to Sections 705.14 (Output Characteristics), 705.100 (Unbalanced Connections), and 705.12 (Point of Connection). The significance of this change is to remove the duplication of requirements and alert users to the specific applicable requirements in Article 705 for fuel cell systems that are interconnected to the utility grid. (Article 705, covering interconnected electrical power production sources, was introduced in the 1990 edition of the NEC and is directly related to grid-connected renewable energy sources.) The concern about interconnected fuel cell systems is related to use of proper transfer and paralleling equipment in a fashion that does not result in inappropriate connection to the grid and possibly back-feed on the utility system, two definite safety concerns for persons and property.

A new provision for wind 
A new article covering small wind electrical systems has been incorporated into the 2011 NEC. Article 694 provides new rules for wind electrical systems rated up to 100 KW.  Wind electrical systems include components such as generators, alternators, inverters, and controllers. Small wind electric systems can be interactive with other electrical power production sources or might be stand-alone systems. They can also have ac or dc output, with or without electrical energy storage such as batteries.

Article 694 includes nine parts—General; Circuit Requirements; Disconnecting Means; Permitted Methods; Grounding; Marking; Connections to Other Sources; Storage Batteries; and Systems Over 600 Volts—and the new rules are similar to those contained in other articles covering renewable energy systems such as PV and fuel cells. This new article includes specific rules related to circuits, disconnects, permitted wiring methods, and guy wire supports. Grounding requirements are provided for systems and non-current-carrying metal parts of equipment. Although the rules for generators, wiring methods, grounding and bonding, conductors, overcurrent protection, and other methods and equipment can be applied to all wind systems large or small, Article 694 provides specific rules on these topics.

During the comment stages of the NEC development process, the qualified-persons requirement was incorporated into this article. Section 694.7 requires all systems covered within the article be installed only by qualified persons. This includes all equipment and associated wiring. Wind systems are not new to the electrical field, but new installation requirements and product safety standards have been aggressively developed for such equipment and systems.

Electric vehicles and energy storage
As the country forges toward energy independence, focus is strengthened on various renewable energy sources that can interconnect with the utility power grid. Photovoltaic, fuel cells, and wind power generating systems fall into this category. The government is accelerating the development and evolution of the electrical power grid in this country. One NEC article that may be affected by the smart grid activity is Article 625 covering requirements for electric vehicles and charging systems. There are significant challenges on the horizon with the pressure to reduce power consumption and at the same time increase the use of electrical vehicles. A change in Article 625 introduces a new defined term, “Plug-In Hybrid Electric Vehicle.” This is a vehicle intended for on-road use with the ability to store and use off-vehicle electrical energy in the rechargeable energy storage system. Plug-in hybrid electric vehicles also have a second source of motive power.  The charging sequences and this additional load will have to be effectively coordinated so that the effort to reduce the stress on the utility grid is not neutralized. This is where renewable energy sources and specifically energy storage will play an important role.  The work to improve power use and develop a more intelligent method to manage the current electrical infrastructure will require educating the consumers, contractors, and all affected.

Looking ahead
Enhancements to current rules in the NEC, along with newly incorporated rules, result in safer electrical systems. As electrical system technologies expand, however, so too do electrical safety concerns. The NEC technical committees will continue to be challenged in each cycle, specifically in areas related to renewable energy sources.

Areas where the NEC will likely see significant changes in future editions are electric vehicle charging systems, battery storage systems, and fuel cells. The ability to store electrical energy is going to become more popular. Plug-in vehicles can be charged and discharged, meaning they could possibly be used as backup power systems for premises wiring—and this will no doubt result in the need for more NEC requirements. While the electrical industry embraces collective efforts to bring renewable energy systems online, safety for persons and property must never be compromised. That’s why understanding the changes in the NEC is essential not just for the people who work on these systems, but for the engineers, designers, safety professionals, and anyone else whose work is potentially affected by a facility’s electrical requirements.

Michael Johnston is executive director of standards and safety for the National Electrical Contractors Association and a member of the NFPA Electrical Section.

SIDEBAR
RELATED CONFERENCE SESSIONS 

Electrical Section Codes and Standards Forum
Jeffrey Sargent, NFPA
Monday, June 7, 8–11 a.m.

The Electrical Section Codes and Standards Forum gives you an opportunity to observe and participate in discussions on the certified amending motions to the 2011 NEC® Committee report. This report will be voted on by NFPA membership at the Technical Committee Reporting Session held at the end of the NFPA Conference. Using an open-forum approach, NEC code-making panel chairs will provide technical background supporting the position taken by their respective code-making panels on the proposals and comments that are the subject of the certified amending motions. At this session, the Electrical Section develops positions to be presented to the NFPA membership at the Association Technical Meeting.

Analysis: NEC Requirements for Critical Operations Power Systems in Industrial Facilities
Eddie Guidry and Wahab Mehmood, Fluor Enterprises, Inc.
Tuesday, June 8, 2:45–3:45 p.m.

The 2008 NEC cycle introduced Article 708, Critical Operations Power Systems (COPS). This article provides the requirements for electrical installations that require a high degree of integrity due to natural or other threats. Oil and gas refineries and some petrochemical facilities are included in this scope. This discussion will cover risk assessments, power distribution requirements, and documentation of the emergency operations plan. It will be of interest to all engineers, designers, inspectors, plant managers, and electricians who deal with industrial installations.

Don’t Call Them Windmills
Redwood Kardon, Code Check Institute
Tuesday, June 8, 2:45–3:45 p.m.

This session discusses the extreme hazards and lack of safety controls for the wind power industry. Typical wind farms being constructed today harbor some of the most extreme available fault currents that EEs and inspectors are likely to encounter. Most are being constructed without the benefit of building permits or third-party inspections or NRTL listings.

Research Planning in Support of the National Electrical Code
Kathleen Almand, Fire Protection Research Foundation; Donald Cook, Shelby County Development Services
Tuesday, June 8, 4:15–5:45 p.m.

In 2008 the Fire Protection Research Foundation formed the Advisory Committee on Electrical Safety Research. Committee members consist of leaders from the NEC panels who meet annually to discuss research needs stemming from code development activities. This session will review current research and research needs in support of current and future NEC code changes.

Spotlight Session:  Proposed Changes to NFPA 70E, Standard for Electrical Safety in the Workplace 
Paul Dobrowsky, Innovative Tech Services, and Palmer Hickman, National Joint Apprenticeship & Training Committee