Although the three-year Code-making cycle for the 2008 edition of the National Electrical Code (NEC) recently closed, the dust has not yet settled on the decision to reaffirm the inclusion of selective coordination for emergency and legally required standby systems.
While not in opposition to selective coordination itself, opponents of the controversial provisions in the NEC continue to seek relief from selective coordination as a national mandate. Although some municipalities, such as New York and Chicago, have required selective coordination under a different name for years, some states, such as Washington, plan to open these provisions up for discussion — and possible amendments — before adopting the 2008 NEC. Massachusetts, for example, already voted in an amendment to the provisions, which will be effective Jan. 1, 2008.
Selective coordination regarding phase devices first appeared in the NEC in 1993 under the jurisdiction of Sec. 620.51, governing total selective coordination for elevator systems. It was then relocated to 620.62 in 1996. Aside from this requirement for elevator circuits, professional engineers have been largely guided by NFPA 110, “Standard for Emergency and Standby Power Systems,” and IEEE Standard 242, “Recommended Practice for Protection and Coordination of Industrial and Commercial Power Systems,” which recognize selective coordination as a design consideration — not a requirement — that may maximize power reliability for both normal and emergency power systems. Licensed professional engineers were given the latitude to determine the course for maximum power system reliability dependent on the given facility's size and occupancy needs as well as installation costs. Then, in 2005, total selective coordination was adopted for NEC Secs. 700.27 (emergency systems) and 701.18 (legally required standby systems), as well as in 517.26 (essential electrical systems of health-care facilities) through the association of the life-safety branch as defined in 517.2 with Art. 700.
Since the 2005 inclusion, the debate over the efficacy of total selective coordination for emergency and standby systems remains unresolved, with the biggest flare-ups taking place during the proposal and comment phases of the most recent Code cycle. The main arguments against the Code requirements for selective coordination in emergency and standby systems are increased installation costs and the difficulty of implementation and enforcement. While there is no argument that selective coordination does improve reliability (and when used on emergency and standby systems may increase safety), detractors say there are no real-world incidents that support the need for it to become a national requirement.
“The proposal is like reducing the speed on interstates to 15 mph,” says Frederic Hartwell, Code consultant and electrician, Hartwell Electrical Services, Inc., Amherst, Mass. “I'm not going to argue that it won't save a few lives if you reduce the speed limit to 15 mph on the interstate, but there would be consequences — and they're unacceptable.”
The ship in a bottle
There are several differing opinions as to how selective coordination for emergency and legally required standby systems found its way into the NEC in 2005. According to Code-Making Panel (CMP) 13, the committee responsible for Articles 700, 701, and 702, Proposal 13-135, which required “All overcurrent devices in emergency systems shall be selectively coordinated… ,” was accepted into the NEC with the goal of increasing reliability and safety. However, some opponents accuse the proposal of being solely in the interests of fuse manufacturers attempting to shift the market share.
“Standards writing is supposed to be objective and altruistic, but manufacturers' battles do occur,” admits James S. Nasby, the National Electrical Manufacturers Association (NEMA), Rosslyn, Va., representative to CMP 13 for the 2005 and 2008 editions and engineering director for Master Control Systems, Inc., Lake Bluff, Ill. “NFPA standards-writing methods tend to keep this to a dull roar, but it certainly still does happen.”
Another theory voiced by opponents of the selective coordination provisions is that the inclusion was an oversight. Jim Degnan, P.E., principal, Sparling, Seattle, suspects a lack of communication contributed to inclusion of the requirement for selective coordination in health-care facilities (517.26). “With development of the 2005 NEC, CMP 15 was not aware that CMP 13 was adding selective coordination for emergency power systems,” he says. “In fact, the reason CMP 15 added 517.26 was to clarify that article 517 requirements for essential electrical systems takes precedence over Article 700.”
Despite the best efforts of vocal opponents, total selective coordination will remain in the 2008 NEC, with only two amendments to the 2005 wording, allowing for exceptions between transformer primary and secondary overcurrent protective devices — where only one overcurrent protective device (or set of overcurrent protective devices) exists on the transformer secondary and between overcurrent protective devices of the same size (ampere rating) in series.
Instead of an appeal to NFPA Standards Council, Hartwell, who is also secretary of the committee that recommends amendments for the Massachusetts Electrical Code (MEC), decided to approach the matter at the state level. “I threw up my hands for 2008,” he says. “As long as there are a couple of engineers running around saying you can do it, then people aren't going to take this out of the Code.”
At the state level, Massachusetts, which is known for being an early adopter of new editions of the NEC, accepts between 60 to 70 amendments to the NEC. “As far as I'm concerned, this is an error — although not literally an error,” says Hartwell. “But the relevant parties have voted for it, so it's not something the standards-making process of the NFPA can do anything about.”
Breaker versus fuse
In theory, selective coordination has very little opposition. It's only in the practical application and enforcement of the articles in the Code that the situation draws fire. “There is an argument that this does enhance the reliability of electrical systems, and from a theoretical engineering standpoint I concur with that,” Degnan says. “However, the likelihood of the public achieving safety benefits from it is so small that it's not justified.”
Extensive experience with coordination studies allows Jim Phillips, P.E., president, Technical Training Group (T2G), Canton, Ohio, to see both sides of the argument. “On one side I'd like to say, ‘Yeah, let's make it all perfect. Let's have it coordinate,’” he says. “But on the other side, it's a very difficult and impractical thing to try to do with breakers.”
The debate surrounding selective coordination has often been described as an issue of breaker versus fuse, with the breaker usually on the losing side. “People say you can use molded-case circuit breakers and achieve perfect coordination, but not really,” Phillips says. “If you're going to perfectly coordinate breakers, you usually have to use more expensive and more complicated solid-state/electronic trip breakers. That drives the costs up.”
Estimates of increased cost for using circuit breakers range from 30% for electrical distribution equipment, 10% for electrical construction costs, and 3% to 5% for the overall cost of a project. “It's going to vary hugely with the project, and it will vary with what the solution is too,” Degnan says. “If you use fuses throughout your system, those percentages would be significantly less — maybe to the point of approaching only a marginal increase. The trouble is, very few people want to use fuses.”
By default, says Hartwell, when adding selective coordination, you must use fuses. “Conventional circuit breakers cannot be used on emergency systems with an available fault current that's within the instantaneous pickup values of the devices that are protecting that system,” he says. “So it's a requirement to use fuses as a practical matter. You can always selectively coordinate with fuses.”
According to some engineers, fuses in selective coordination are not without problems. If a fuse blows, it may take some time to get the system back in service, especially if a replacement fuse isn't immediately available. In addition, there can be difficulty finding a qualified person to open the switchgear and test for which fuse to replace, as well as the potential exposure to energized systems. “Depending on the equipment's design, there's a pretty good chance that the line side of the fused switch will still be energized, leading to an exposure to energized parts,”says Phillips.
Degnan argues that this danger is inherent in selective coordination itself. “Selective coordination requires both circuit breakers and fuses to wait before opening to give whatever protective device that's downstream a better chance of interrupting the circuit first,” he says. “By waiting, the device introduces more energy into the system, and this has the potential to create more harm, particularly if there is an electrician doing maintenance on the system.”
Proponents of mandating selective coordination say there are ways around these dangers. “You can limit fault currents, and you can still selectively coordinate,” Nasby says. “One advantage that fuses have is that most tend to be current limiting. But there are current-limiting breakers available as well. It's less expensive to do it with fuses, but it can be done with breakers, and currently is being done with breakers. Some places prefer not to use fuses, but it's not impossible to do with breakers.”
Beyond technical and cost concerns surrounding how selective coordination of emergency and standby systems can be achieved, many opponents of the mandate in the NEC are asking not how — but should — selective coordination be a requirement on every new system. “The Code now requires us to design for this contingency, and it's expensive to do so,” Degnan says. “Without some practical knowledge of this having affected the safety of the public, it doesn't seem prudent to be doing that design and to be spending that money.”
Opponents to the inclusion of selective coordination in the NEC claim there are no reported incidents in which the lack of selective coordination has caused a problem, even if selective coordination itself will increase reliability and safety. They say they are being dismissed as disregarding safety issues altogether. “It's almost like saying that I have a foolproof way to reduce the fatality rate and who are you to put economics over the safety of human lives?” Hartwell says. “This is the unwillingness to be intellectually honest about calculated risk. It's very difficult to get people to face this.”
In response, Nasby asks detractors to list the essential emergency systems they'd want to risk going offline. He says it's difficult to calculate risk when it's your family on the top floor of a high-rise hotel. “Typically, no building owner will install anymore emergency services than are required, and what is required for that building is important,” Nasby says. “You don't want to lose lights in the stairwell or the emergency elevators, and you don't want a fault on one of these services to take out anything else. There can be exceptions, but typically faults are localized. The premise of distribution systems is that a fault on one circuit doesn't propagate upstream — and that's what this is asking for.”
The debate surrounding selective coordination has been compared to similar arguments regarding arc fault circuit interrupters (AFCIs). The added costs and effort to selectively coordinate emergency and standby systems may have the same effect on the institutional market as installing AFCIs may have on the residential market. “There are some people asking if both of these items adopted in the last two Code cycles actually work and perform as they're supposed to or are necessary,” says Bill Eckroth, plan review supervisor, Department of Labor and Industries, State of Washington. “There has to be a litmus test to prove that this is necessary, and not only to show that it promotes life safety but also to show that there is a problem. Some folks feel the litmus test was never met regarding these issues. I don't think anybody would be opposed to it if it was shown that this is really going to save lives.”
According to Nasby, with very rare exceptions, existing installations are always grandfathered in when a Code change is made. “It's not meant to be retroactive,” Nasby says. “Grandfathering is pretty much automatic.”
However, citing a lack of direction in the Code regarding the selective coordination of existing electrical systems, the engineers of the Electric League of the Pacific Northwest, Bellevue, Wash., obtained a rule change to exempt electrical systems installed prior to June 20, 2006, from selective coordination. Because Washington State had already adopted the 2005 NEC it modified the rules so that only systems installed after the June 20, 2006, date must fully comply with the selectivity requirements of Articles 700.27 and 701.18. “It was not clear what to do with existing installations when they're modified,” says Eckroth. “We didn't want to enforce the requirements for selective coordination because load was being added to an existing system.”
There are two aspects to Washington State's rule. “If you're only adding loads to existing panelboards, coordination is not required,” Eckroth says. “However, if you're developing a system — adding a couple of levels to an existing emergency distribution system — then only the part that you are adding would have to be coordinated. You wouldn't have to coordinate the rest of the system.”
All new systems built in Washington State must comply with the requirements mandated by 2005 NEC. “We require a statement in writing and stamped from the electrical engineer,” Eckroth says. “That's how it's enforced in plan review. The system, when installed, will be selectively coordinated, and that's it.”
As far as the 2008 NEC goes, the state's plan for adoption won't be before the end of December 2008. “We'll be reviewing changes to the NEC and make a determination about what the current modifications to the Code are and their impact,” Eckroth says. “We're probably not going to be changing our rules regarding selective coordination unless they've addressed existing systems in the 2008, which I believe they haven't.”
Exceptions to the rule
Modifications are less likely to be made once a regulation is adopted. “It's very difficult to adopt a Code change and then go back and say, ‘Well, we didn't mean for this part to be included,’” says Alan Toole, independent manufacturers representative for PowerPlus, Seattle. “It's easier to make exclusions ahead of time and adopt from there.”
However, some lessons about certain Code requirements may be learned only after the regulations have been accepted. “Once we ended up enforcing the Code, we heard, ‘Oh my God. Do you realize what the impact of this is going to be?’” says Eckroth. “I think that's one of the reasons we're going to take a really hard look at the changes in the 2008 Code. We want to make sure everybody discusses the issues ahead of time. We're going to carefully examine the issues and then move forward.”
Contrary to what some proponents of selective coordination in the NEC are saying, opponents to its inclusion aren't trying to find a way around selectively coordinated systems altogether. “We didn't throw it out,” Hartwell says. “We added an exception that says a licensed professional engineer can do a coordination study and basically do the best he or she can.”
According to Phillips, Massachusetts may not be the only state making this exception. “What I've heard in one or two states is that their local authorities are saying for now they're going to leave it up to the design professionals to figure it out,” he says. “I think it means they're as confused as everybody else so they're throwing their hands up in the air until they get it straightened out. They're saying, ‘We don't know what to tell you, so do what you can.’”
Sidebar: Selective Coordination Equipment Standards
One major concern in the debate over the selective coordination mandate in 2008 NEC is the lack of official safety standards for the equipment. “For almost all equipment in the electric industry, there are safety standards,” says Jim Degnan, P.E., principal, Sparling, Seattle. “The equipment is designed to meet requirements established by independent safety organizations, such as Underwriters Laboratories (UL). If it's so constructed, we can say that it's safe, or that it's going to perform as expected. UL has no criteria for what constitutes selective coordination.”
In the absence of a UL rating, says Degnan, each manufacturer can state what it construes to be selective coordination, and there are no standards between manufacturers as to what constitutes selective coordination. “Basically, the engineers have to take the manufacturer's word for it that something is selectively coordinated. This means that once an owner has invested in overcurrent protection by a single manufacturer, then that owner would be obligated to buy additional equipment by that manufacturer for it to continue to be selectively coordinated. Before, they could've bought equipment from any manufacturer, and the engineer could've applied some appropriate judgment to determine the degree of selective coordination that was likely to occur based on different manufacturers' equipment.”
Proponents of the selective coordination requirement in the 2008 NEC say it's only a matter of time before this concern is abolished. Proposal 13-135 has been called a “manufacturers' battle,” and that's how many think this matter of a lack of equipment standards will be solved. “This battle will be resolved when manufacturers start offering more products,” says James S. Nasby, CMP 13 principal for the 2005 and 2008 editions and engineering director, Master Control Systems, Inc., Lake Bluff, Ill. “Then, other manufacturers will be all over it.”
Sidebar: Voluntary Adoption
Through its field representatives, Rosslyn, Va.-based National Electrical Manufacturers Association (NEMA) tracks the adoption of the NEC by states and major local jurisdictions. The timing for adoption varies by state and municipality, and some jurisdictions adopt the NEC only after making amendments to the document. Therefore, electrical codes differ throughout the country and even within individual states.
Municipal jurisdictions may amend the latest edition of the NEC adopted by the states in which they are located. For example, Washington State operates under the 2005 NEC, but Seattle approved the 2005 Seattle Electrical Code on Sept. 19, 2005. However, the local jurisdiction may only require stricter requirements than the state mandates. “Local jurisdictions can take a harder line from what the state has adopted,” says Bill Eckroth, plan review supervisor, Department of Labor and Industries, State of Washington. “If we've adopted selective coordination but have modified it under rule, then that would be the minimum that would have to be met.”