Ever since it was first introduced by the National Institute for Occupational Safety and Health (NIOSH) in 2007, the Prevention through Design (PtD) initiative has been making great strides in preventing or reducing occupational injuries, illnesses and fatalities by considering how to prevent hazards in all designs that impact workers.
According to G. Scott Earnest, acting director for the Office of Construction Safety and Health at NIOSH, Prevention through Design engages partners in industry, labor, trade associations, professional organizations and academia to design occupational safety and health hazards to best protect workers.
“Quite simply, this approach works,” he said. “When you’re able to design out hazards early in the life cycle of a construction project, safety and health hazards can be eliminated. This is particularly important when applied to falls, struck-by, caught in between and electrocution—the ‘Focus Four’ hazards that account for a significant portion of fatal injuries each year in the construction industry.”
In the decade-plus since the program was introduced, Earnest and other industry experts confirm that the principles of Prevention through Design have been increasingly (and successfully) incorporated into electrical product design and contracting industry processes at many levels, from voluntary consensus standards and engineering to manufacturing and more.
PTD Concepts in Codes and Standards
Michael Johnston, executive director of standards and safety at the National Electrical Contractors Association, confirmed that PtD philosophies have been incrementally migrating into requirements in the National Electrical Code.
“The NEC has multiple installation requirements that directly support and facilitate the achievement of electrical safety in the workplace and safety by design,” Johnston said. “An excellent example of this is covered in Section 110.25 of the NEC, which addresses locking means requirements at switches and circuit breakers. This rule requires that if a disconnecting means is required to be lockable open elsewhere in this Code, it shall be capable of being locked in the open position. The provisions for locking shall remain in place with or without the lock installed. This requirement relates to field conditions and scenarios that require locking means when disconnects are located out of sight of the equipment they supply.”
According to Johnston, many types of equipment (disconnect switches, motor controllers, circuit breakers, etc.) provide an inherent means of locking out a switch or circuit breaker provided in the design of the equipment.
“Manufacturers of electrical equipment also produce accessories for equipment that can be installed where the locking means isn’t present, thus providing a solution to meet this requirement,” Johnston said. “There’s a direct relationship between NFPA 70E and the NEC in that NFPA 70E has requirements to create electrically safe working conditions (elimination of the hazard); the process involves proper application of lockout/tagout rules in Article 120 of NFPA 70E.”
In more recent editions of the NEC, Johnston said, new rules result in the reduction in severity of fire and explosions on properties and electrical shock/electrocution of people.
“Examples of the newer, increasing presence of safety by design concepts are found in NEC sections 240.67 and 240.87, which require methods of reducing arc energy in equipment at the 1,200-ampere threshold and higher; such equipment is much safer and more likely to return to use if an arcing event were to occur as opposed to becoming destroyed by an arcing burndown. Two other NEC provisions that align with safety by design concepts include the requirement for barriers in all service equipment, and the prohibition of the six service disconnect allowance in a single enclosure—both revisions reduce the likelihood of inadvertent contact with live busbars within service equipment,” he said.
Johnston noted that other methods of achieving a level of safety by design include prefabrication of electrical installations in controlled environments and temporary construction wiring systems for projects.
PTD in Engineering
When it comes to reducing arc energy in compliance with NFPA 70E, said Tom Domitrovich, vice president of technical sales at Eaton. Engineers can incorporate PtD principles to reduce the likelihood of an event occurring and its severity. Among methods used to reduce the likelihood of an event are the incorporation of local disconnects that electrical workers can turn off when justified energized work isn’t warranted, and “finger safe” provisions that help reduce the likelihood of an electrical worker accidentally coming into contact with areas leading to shock and arc flash.
“Placement of electrical distribution equipment in conditioned areas free from dirt, dust and corrosive materials is another great way to extend the longevity of equipment and reduce the need for the maintenance that can put workers in harm’s way,” Domitrovich said. “We can show building owners how critical proper working space is for reducing hazards and saving lives.”
Because the severity of an arc flash event is largely affected by the parameters of current and time, “the best way for engineers to address the severity of an event is to implement methods to reduce clearing time,” he said. “While it’s difficult to control how much current will flow during an event, it’s not difficult—with some planning and understanding of overcurrent protective devices [OCPD]—to reduce the time.”
He noted that reducing severity also translates into a reduced likelihood of having to replace damaged equipment.
“An event where everyone walks away safe and equipment doesn’t have to be replaced is a success. Combining the aforementioned steps to reduce the likelihood with steps to reduce time is the perfect recipe for safety,” he said.
Domitrovich said the first step in reducing clearing time for greater safety is to understand short-circuit currents within the power system.
“Minimum short-circuit currents are critical as lower fault currents can be placed in the area of the trip curve for a circuit breaker or fuse where longer clearing times are expected, increasing incident energy,” he said. “Maximum short-circuit currents are critical, but, in reality, if those higher currents are in the fast clearing times of the OCPD, the incident energy will be able to be addressed by the OCPD for the electrical worker. The bottom-line message is to not be afraid of higher fault currents because they increase the likelihood of faster clearing times during arcing faults.”
When it comes to arc flash reduction, engineers must also recognize that some areas of the power distribution system and certain conditions of design may be more prone to higher incident energy than others.
As such, Domitrovich said, “strategic design decisions can be made to address higher-risk areas where the likelihood of justified energized work is high and increase safety.”
PtD in Manufacturing/Sales
Prevention through Design principles have also been embraced at the manufacturing level. Schneider Electric integrates innovative technologies, IT solutions and data analytics through its EcoStruxure platform to enable smart decisions for safety, control, operations, maintenance and business, according to Alan Manche, Schneider Electric’s vice president of external affairs, North America operations,
“At our state-of-the-art smart factory in Lexington, Ky., augmented reality technology is utilized to overlay machine information on a real-time view of the machine via a mobile device, reducing the time and cost of operations and maintenance by providing process information in real time,” Manche said. “It minimizes errors during maintenance by guiding operators with step-by-step procedures and also provides hazardous equipment information without exposure to the hazard.”
Schneider Electric’s Lexington facility also uses human-machine interface devices every day to read information, acknowledge faults and operate equipment. It is additionally expanding the use of QR codes on electrical equipment and components to provide quick access to installation, operation and maintenance information by installers and operators.
According to Rodney West, senior staff engineer with Schneider Electric, “Today’s facility designers and equipment specifiers are putting more emphasis up front on features that reduce risk throughout the equipment life cycle.”
This isn’t just happening by chance.
“[It] is a result of real-world needs being met with education, technology and a coordinated effort to align the requirements found in the NEC, NFPA 70E and NFPA 70B,” West said, who serves on the technical committees for all three documents.
Thanks to industry advancements, West noted that some types of electrical equipment, such as power circuit breakers, can now provide immediate access to real-time diagnostic information such as voltage, current, event logs, trip history and more, all of which can help facility operators quickly and efficiently complete their initial troubleshooting and diagnostics.
Additionally, “these PtD features continue to deliver benefits years after installation as they enable electrical contractors to acquire diagnostic information without opening doors, removing covers or performing other tasks that may expose them to shock or arc flash hazards,” he said.
West added that some of these open compute project devices can now be remotely opened or closed using Bluetooth technology that allows the equipment to be paired with a phone, which can be especially useful after completion of maintenance inside the equipment.
The overall Impact
Experts agree that the Prevention through Design initiative has been effective in focusing the industry on preventative safety measures everywhere from design and development to the installation and usage stages.
“Safety shouldn’t be an afterthought, and Prevention through Design is the best way to increase safety because intentional steps are taken and designed in to address the hazards,” Domitrovich said.
“PtD is an important approach to addressing occupational safety and health hazards and, when implemented properly, can be extremely effective because it follows the hierarchy of controls,” Earnest said. “As such, the focus is properly placed on designing out hazards rather than using other approaches later in the process such as administrative controls or personal protective equipment, which are generally less effective.”
Looking ahead, “my hope is that use of PtD will expand within the construction industry and continue to reduce safety and health hazards,” he said.