UL 496 CRD-2011 UL Standard for Safety Lampholders - Section Paragraph Reference Tables 6 and Clause 4 9 9 Subject Clarification of creepage distances and clearances measurements .pdf

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1、UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULUNDERWRITERS LABORATORIES INC. CERTIFICATION REQUIREMENT DECISIONThis Certification Requirement Decision is prepared and published by Underwriters Laboratories Inc.(UL). It is normative for the a

2、pplicable UL Product Certification Program(s); however, it is currently notpart of the UL Standard(s) referenced below.Product Category (CCN): OKCT/OKCT7, OLFB2Standard Number: UL 496Edition Date: September 30, 2008Edition Number: 13Section / Paragraph Reference: Tables 6 and Clause 4.9.9Subject: Cl

3、arification of creepage distances and clearances measurementsDECISION:4.9.9 Creepage distances and clearances shall be measured between uninsulated live parts:a) of opposite polarity;b) and non-current-carrying metal parts;c) and the intended mounting surface; andd) non-current-carrying metal parts

4、likely to be exposed to contact when the device is installedin the intended manner shall comply with Table 6.4.9.9.1 The creepage distances and clearances from the columns of Table 6 labeled “At wiring terminals”shall apply to points of the holder where the supply connections are made (i.e. points t

5、hat may come incontact with supply conductors). Creepage distances and clearances from the columns of Table 6 labeled“At points other than wiring terminals” shall apply to distances between points other than wiring terminals,including terminal contacts.RATIONALE FOR DECISION:Table 6 of UL 496 specif

6、ies separate minimum creepage distances and clearances for points “at wiringterminals” versus “points other than wiring terminals. This distinction is clear in the requirements forholders intended for dry and damp locations and has caused confusion for some lampholder constructionswhere the terminal

7、 contacts are a direct extension of the wiring terminals. These constructions can befound in some twist and lock bipin holder configurations that are used for certain fluorescent and LEDlamps (e.g. ANSI_ANSLG GU24 base lamps). The distinction in Table 6 is necessary because largerspacings are requir

8、ed for points at wiring terminals where stray strands or terminal parts may move duringlead insertion and may result in reduced spacing. This CRD clarifies how spacing measurements shouldbe evaluated to the different columns of Table 6.Copyright 2011 Underwriters Laboratories Inc.UL, in performing i

9、ts functions in accordance with its objectives, does not guarantee or warrant thecorrectness of Certification Requirement Decisions it may issue or that they will be recognized or adoptedby anyone. Certification Requirement Decisions are the opinion of Underwriters Laboratories Inc. inpractically ap

10、plying the requirements of the standard. They do not represent formal interpretations of thestandard under American National Standards Institute (ANSI) processes. UL shall not be responsible toanyone for the use of or reliance upon Certification Requirement Decisions by anyone. UL shall not incurUL

11、COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULany obligation or liability for damages, including consequential damages, arising out of or in connectionwith the use or reliance upon Certification Requirement Decisions. The electronic version of theCertification Requirement Decision is the current version and previously printed copies may be outdated.This document is published as a service to ULs certification customersSTANDARD NUMBER: UL 496 -2-