UL 943 TGD-2018 UL Standard for Safety Ground-Fault Circuit-Interrupters - Subject UL 943 Visual Indicator Requirement (Edition 5 May 17 2016).pdf

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1、UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULUL TECHNICAL GUIDANCE DOCUMENTSThis Document is prepared and published by UL.Product Category (CCN): KCXS-2/7/8, DKUY-2/7, DIYG-7, KCXX-7Standard Number: 943Standard Title: Standard for Ground Fa

2、ult Circuit InterruptersEdition Date: May 17, 2016Edition Number: 5Subject: UL 943 “Visual Indicator” RequirementGUIDANCE:Handle movement of a circuit breaker is a “visual indication” of the status of the breaker. Circuit breakertype GFCIs provided with instructions noting that when the supervisory

3、TEST button is operated, the “lack”of handle movement indicates a malfunction and that the device will no longer provide GFCI protectionand should be replaced, is one acceptable method to provide “visual indication” as required by 6.31.8(A).BACKGROUND:A recent revision to UL 943 removes the exemptio

4、n for the auto monitor function simulated fault test fromclauses 6.31.2(D) (open circuit of the trip solenoid) and 6.31.2(E) (open switching semiconductorsupplying the trip solenoid) for circuit breaker type ground fault circuit interrupters (GFCIs). Without theexemption, all GFCIs shall either prov

5、ide the level of protection outlined in Clause 5.16, or comply withthe alternate requirements specified in clause 6.31.8. When applying 6.31.8(A), the GFCI shall “visually oraudibly indicates if it does not interrupt the electric circuit to all loads, when the manually operatedsupervisory test funct

6、ion shall be performed, after which the reset button shall be operated”.RATIONALE FOR GUIDANCE:UL 943 requires “visual indication” (Clause 6.31.8(A). In contrast, the Standard for AFCIs, UL 1699,requires that “results of the test shall be made known to the user by a positive visual indication” (Clau

7、se15.2).Normal operation of a GFCI circuit breaker supervisory test circuit (by pressing the TEST button) resultsin the user visually observing the handle moving to a middle trip position. In an event of a malfunctioningGFCI circuit breaker, one option is for the user to visually observe that the tr

8、ip handle does not move afterpressing the TEST button.Since UL 943 does not require a “positive visual indication”, the lack of handle movement is an acceptable“visual indication.” For this to be considered a “visual indication” the GFCI circuit breaker instructions shallindicate that the operation

9、of the supervisory test circuit results in the circuit breaker handle moving to the“tripped” position, and that if this does not occur, it is an indication of a malfunction and the breaker shouldbe replaced by a qualified electrician.Copyright 2018 UL LLCULs Technical Guidance Documents are intended

10、 to be used as reference documentation and aredesigned to provide assistance in understanding the application of requirements contained in thecorresponding UL Standard, provide assistance in addressing the use and applications of the respectiveproducts covered by the associated UL Standard(s), or both.UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULThese guidelines do not contain any construction or performance requirements.STANDARD NUMBER: 943 -2-