New Code Requirement Mandates PV Shut Down Device
March 25, 2015
Rooftop photovoltaic (PV) installations are increasingly common in commercial facilities, as market pressures make the technology more affordable and easy to deploy. This, however, poses increased risk to first responders in the event of a fire. They may have to go up to the roof to vent the facility and then risk coming into contact with energized equipment.
A new requirement in the 2014 National Electric Code (NEC) directly addresses the need to power down PV systems in an emergency. Since the 1980s, codes have included language regarding the safety requirements for PV systems, but these have dealt with properly identifying PV conductors and providing arc-fault protection, according to an article in NFPA Journal.
The 2014 NEC requirement mandates a rapid-shut down device for the PV system, which would reduce "the voltage level to not more than 30 volts, and the overall power in the system to not greater than 240 volt-amperes, levels that mitigate shock and electrical burn hazards. This reduction in energy must occur in PV system conductors that are more than 10 feet (3 meters) from the array or to interior PV system conductors that are located more than 5 feet (1.5 meters) from where they enter a building," according to the article. In addition, the reduction must occur within 10 seconds of activation.
Adoption of the code varies by jurisdiction, so facility managers will want to check to see what applies in their area. For those who would want to proactively comply with the code in the interest of life safety at their facility, facility managers can also consider installing utility-interactive string inverters and micro inverters to achieve the intended result, if a complete certified, or listed, rapid shutdown package is not readily available in their area, according to the article.
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