Challenge: The NFPA NEC 2017 Sec. 210.8 requires electrically operated commercial kitchen equipment with “single-phase receptacles rated 150 volts to ground or less, 50 amperes or less, and three phase receptacles rated 150 volts to ground or less, 100 amperes or less” to have GFCI for personnel protection installed. Prior to this change, only 15- and 20-Amp single phase circuits of 125 volts or less needed this level of ground fault protection, with circuit breakers and receptacles meeting this requirement being readily available and quite common. Requirements above 20 amps or needing three-phase protection is a more difficult issue.
Additionally, commercial kitchen steamers and grills sometimes retain humidity while stored prior to installation. To address this issue, units must be “burned in” or energized for a minimum of two hours prior to normal use. The additional moisture present during this process increases the ground fault leakage to a point above the 5-mA desired trip level. To avoid nuisance tripping during the burn in cycle, a ground fault relay needs to allow a temporary increase in the setpoint.
Solution: The NK Technologies Tri-Set relays offer adjustable capabilities as a standard feature. A factory placed range jumper is installed at the highest setpoint (30 mA) allowing the equipment to operate as required during the initial burn-in period. Once the burn in cycle is completed, the relay can be readjusted to accommodate the desired ongoing 5 mA setpoint. Because of their rugged solid core design and wide operating temperature range capabilities, AG and AGL ground fault relays work well in this environment.