"The United States National Electrical Code (NEC?)" Section 250.21 (B) Requirement: ungrounded AC systems installed on the system to the detector. PGR-3100 can use voltage transformers (PTs) to reduce system voltage to be applied to any system voltage. For less than 240Vac system voltage, you do not need to use specific pressure device (PTs) and direct access to the voltage input. ? In line with "the U.S. National Electrical Code (NEC?)" Section 250.21 (B) the terms of the ungrounded system requirements? Show the existence of ground fault and phase fault verify the proper operation of the lamp test button? To improve the reliability with a backup of long-life LED (two per phase) IEEE device number 27, 64 input voltages up to 240Vac 50/60Hz LED is off line to ground <30Vac size high 108mm (4.3 "); width 88.9mm (3.5"); deep 54mm (2.1 ") test button standard warranty period of five years, selective installation of panel