Not long ago, when a manufacturer decided to upgrade an assembly line, the power supply to a steel-bending machine needed an essential feature. Surge protection was required to prevent electrical damage to the machine’s safety interlock circuits, which play a vital role in shutting the machine off to protect the user.
That’s just one of a growing number of scenarios calling for the application of surge protective devices (SPDs), which act as pressure relief valves and send brief spikes of excess voltage to a ground wire to help prevent damage to electronics.
“As robotics, automation and more sophisticated technologies have infiltrated the manufacturing scene, more problems related to surge and power quality have begun to play out,” said Karla Zavala, product marketing manager for Midwest electrical products at ABB, Cary, N.C., which manufacturers several SPD lines.
“Many manufacturing operations are located in older buildings, which presents its own set of problems,” Zavala said. “We’ve identified a complete retrofit market for surge protection in manufacturing alone.”
Zavala insists the need for it is growing.
“Electronic technology is everywhere in our appliances—stoves and refrigerators, which are expensive to replace. It’s in our microwaves, our smoke detectors, lighting controls, security systems,” she said. “Our increasing reliance on digital technology is driving the need for surge protection, because electronic devices are so susceptible to damage.”
SPDs in the NEC
“It’s important for electricians and electrical contractors to realize that surge protection has gone from being an option to becoming a requirement in many instances,” said Michael Johnston, NECA’s executive director of codes and standards. “Twenty years ago, you didn’t see the amount of surge protection that’s become necessary not just for resilience and consistency of electrical service, but also public safety. There are a number of specific code requirements related to surge protection that just didn’t exist before. The electrical code is peppered with references. It continues to evolve.”
Fortunately for the operator of the pipe-bending machine, National Electrical Code (NEC) 670.6 states that industrial machinery with safety lock circuits shall have surge protection.
Many among us are alive and well, thanks to other NEC requirements and electricians who adhered to them when performing installations. In recent years, NEC 620.51(E), which requires surge protection for emergency loads, added requirements for circuits supplying elevators, escalators, moving sidewalks, platform lifts and chairlifts.
In several state and local jurisdictions, buildings now operate with less chance of fires burning out of control, thanks to NEC 695.15, which requires SPDs to be installed in or on the fire pump controllers for sprinkler systems. In a 2014 Fire Protection Research Foundation survey surges were found to have damaged 12% of fire pumps.
For critical operation data systems requiring continuous operation to maintain public safety, emergency management or national security, NEC 645.18 requires surge protection. These systems can involve everything from air defense and air-quality monitoring to analysis of local water treatment.
NEC 708.20 requires SPDs at all voltage distribution levels for the protection of critical operation power systems, including HVAC, fire alarms, security systems, communications and signaling for critical operations areas.
To ensure reliable emergency power distribution for loads involving life safety, NEC 700.8 requires installation of a listed SPD in or on the switchboards and panelboards of emergency systems.
All these NEC requirements pertain to safety and emergency systems. But many more articles requiring surge protection exist, and more are likely to come, Johnston said.
Understanding surges and SPDs
The most powerful and unpredictable form of surge is lightning, which can blow transformers and knock out power to thousands of customers. Along with utility load switching, it can inflict the greatest damage to electrical systems and the equipment they supply.
But this only accounts for a small percentage of the power fluctuations that disrupt function, delete files, cause equipment to fail and result in costly downtime.
In industrial settings, the bulk of transient voltage spikes, or surges, originate from internal sources such as internal load switching, variable frequency drives, lighting, air handlers and compressors, Zavala said. Motors and compressors switching on create surges in voltage that even out as equipment comes up to speed.
Richard Bingham, a retired electrical engineer and widely published expert on power quality, appreciates the value of surge protection.
“In selecting surge protection, you always need to consider the cost of the protection versus the cost of the damage,” he said. “It becomes apparent that it’s essential to protect expensive equipment.”
SPDs come in four types and apply to four levels of service based on the NEC definition for surge protective device:
- The first level (Type 1) is at the service entrance, not over 1,000V.
- The second level (Type 2) is on the load side of the service disconnect overcurrent device, switchgear or panelboard, under 1,000V.
- The third level (Type 3) is typically at point of use, such as with an MRI machine.
- The fourth level (Type 4) consists of component SPDs, which are typically a recognized component of an overall equipment assembly. See
NEC100 for the exact definition of SPD types.
Zavala recommends a “cascading approach to surge protection” at the first three levels. As a representative of ABB, she approaches engineers about including surge protection in building specs.
Johnston and Bingham said points of protection can differ, however, depending on building configurations and usage needs.
“Everyone’s needs are different,” Johnston said. “It’s best to conduct an assessment. What may be enough for one user might not be enough for another.”
ABB; Schneider Electric, Andover, Mass.; Grainger, Lake Forest, Ill.; Eaton, Moon Township, Pa.; and Siemens, Norcross, Ga., seek to educate electrical contractors and their customers on the value of surge protection.
Likewise, Johnston has taken to making presentations about “over-voltage protection.” A recent presentation included references to the many settings requiring surge protection, precautions for installing them and the evolution of SPD technology. He also provided an extensive list of NEC articles for required surge protection in electrical installations and equipment, including articles 230, 501, 502, 820, 708, 620, 700, 490, 695, 670, 645, 646, 399, 810, 406 and 694. His list is a work in progress. Vulnerabilities to damage from surges and power fluctuations continue to grow as businesses and homes employ green technologies and LED lighting and turn over more controls to automation, Zavala said.
Many SPD manufacturers use the term “power conditioning.” SPDs condition the voltage by removing surges, Bingham said.
“However, they cannot provide energy to compensate for the reduced voltage of a sag or dip, nor do they filter out harmonics,” he said.
These related power conditioning devices—uninterruptible power sources and harmonics filters—do, however, contain SPDs for their own protection and for the equipment they supply.
Perhaps more important, power conditioning implies that fully addressing the gamut of power fluctuations is a process requiring monitoring and maintenance, not a permanent fix. Therefore, timely replacement of worn-out SPDs is crucial.
“It’s a lot like having an insurance plan,” Zavala said. “You want to keep your policy up-to-date to protect your assets. Surge protectors are designed to take so many hits and then they’re done. They have to be replaced.”
The replacement process can require shutting down entire systems. ABB overcomes this with SPDs that can be installed on equipment exteriors.
“In high-use settings, this can help prevent a significant loss of business,” she said. “In the case of a water treatment plant, it can help prevent a public health emergency.”
To enable building engineers and users to know where SPDs are in their useful life and schedule replacement, manufacturers offer color-coded indicators. Some of ABB’s SPDs feature remote monitoring with time stamping and surge assessments that can be accessed online.
Regardless of which SPD brand an electrical contractor works with, Zavala emphasized the importance of only installing SPDs tested and approved by Underwriters Laboratories that meet IEEE standards.
For many years, surge protection was needed the most in commercial settings, but protecting electronic devices in homes was given top priority in finalizing the 2020 Code .
As a result, NEC 230.67 requires all new dwellings and retrofits for existing homes to install surge protectors at level 1 or 2.
Zavala suggests more protection and power conditioning may be needed, given the bidirectional flow of energy related to home solar power generation and residents relying on electronics to remotely control HVAC, lighting, security and appliance use.
“What we’ve seen with moving over to the smart power grid systems [is that] they do generate more fluctuations with constant switching from one load to another,” she said.
With more workers maintaining home offices, more electronics need protection.
Weather events and power interruptions prompting the use of standby generators also can create inrushes of damaging surges to homes, Johnston said. The situation is likely to occur more frequently as newer electric vehicles are outfitted to provide standby power for homes through use of utility-interactive electric vehicle supply equipment.
“Electricians and electrical contractors, not the car manufacturers, will be responsible for any related needs for surge protection,” he said. “Industry trends currently show there’s no near end to the growing and identified surge protection needs.”