UL 3741
UL CSDS Proposal
Edition 1
Published Date: August 20, 2024
Last Revision: December 08, 2020
Scope
037410-000000-0000001 Scope
1 Introduction
1 1.1 Fire fighters (FF) performing operations involving buildings with attached or integrated Photovoltaic (PV) arrays may be exposed to electrical hazards from damaged PV equipment. These requirements provide a means for evaluation of PV Hazard Control components, equipment and systems that provide a reduced level of shock hazard from energized PV system equipment and circuits located within the PV array after the operation of hazard control initiation function(s) where required, such as but not limited to any PV Rapid Shutdown Equipment (PVRSE) or PV Rapid Shutdown Systems (PVRSS) that comply with UL 1741 in the United States and CSA C22.2 No 330 in Canada.
NOTE: Damaged PV equipment in arrays includes damage as a result of fire fighter (FF) interaction as identified throughout this standard and also common PV faults such as PV array ground faults.
1 1.2 This standard is based on the presupposition that the PV array is installed by qualified persons in accordance with the installation instructions and all applicable installation codes and standards. Evaluation to this standard should not replace other requirements addressing the control of power source(s) for the purposes of worker safety during installation or maintenance. Energized circuits can remain in some PV array equipment after any required hazard control initiation function is operated.
NOTE: Requirements for PV arrays addressed in this standard are intended for compliance with the National Electrical Code (NEC), NFPA 70, 2017 and 2020 editions and their requirements for controlling electrical shock hazards inside the array boundary as addressed in NEC section 690.12(B)(2), Rapid Shutdown of PV Systems on Buildings and with the Canadian Electrical Code (CE Code) C22.1. A PVHCS may or may not additionally comply with the 30V in 30 seconds requirements outside the PV array as required in 690.12 (B)(1).
1 1.3 This standard evaluates the hazards associated with potential exposure to DC currents through defined fire fighter (FF) interactions. Alternating current (AC) exposure is limited to not more than 15 Vac, 8A and 240VA for any circuit within the array boundary.
NOTE: This ac voltage limit is aligned with the PVRS requirements in UL 1741 and general electric shock limits.