UL 1088 CRD-2018 UL Standard for Safety Temporary Lighting Strings - Section Paragraph Reference 18 1 4 Subject Metallic Lamp Guards that are Unlikely to Become Energized (Edition.pdf

1、UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULUNDERWRITERS LABORATORIES INC. CERTIFICATION REQUIREMENT DECISIONThis Certification Requirement Decision is prepared by UL LLC. It is normative for the applicable ULProduct Certification Program(

2、s); however, it is currently not part of the UL Standard(s) referencedbelow.Product Category (CCN): XBRT, XBRT7Standard Number: UL 1088Standard Title: Standard for Temporary Lighting StringsEdition Date: July 10, 2015Edition Number: 7Section / Paragraph Reference: 18.1.4Subject: Metallic Lamp Guards

3、 that are Unlikely to Become EnergizedDECISION:18.1.4 A metal lamp guard with or without a nonmetallic coating shall be positively bonded to theequipment grounding conductor of the string.Exception No. 1: A metal lamp guard that is shipped separate from the lampholder shall be provided withinstructi

4、ons (see 44.17) for positive connection to the equipment grounding conductor of the string unlessthe bonding connection is automatically obtained.Exception No. 2: A metal lamp guard that must be removed for relamping shall be designed so that thebonding connection is automatically provided on assemb

5、ly to the lampholder.Exception No. 3: A metal lamp guard of a temporary lighting string employing non-replaceable lightsources that is unlikely to become energized.RATIONALE FOR DECISION:Prior to the 6th Edition, UL 1088 only covered temporary lighting strings employing Edison screw baselampholders.

6、 As a result the requirements were broadly written to mitigate inherent risks of electric shockassociated with the use of replaceable lamps in a construction site environment. Now the scope of UL1088 also covers temporary lighting strings employing non-replaceable LED light sources. This allowssome

7、of the specific risk of shock conditions originally anticipated by the standard to be eliminated ormitigated by product design. While this CRD does not modify the existing requirements applicable totraditional lighting strings employing lamps with Edison screw bases, it provides an alternative appro

8、achfor grounding requirements in new temporary lighting strings with non-replaceable LED light sources.The potential risk of electric shock is addressed in ANSI/UL 1088 / CAN/ULC-S1088 by multiple layers ofconstruction requirements including minimum spacings, adequacy of insulation, grounding and bo

9、nding,as well as testing requirements including abnormal operation, dielectric voltage withstand and continuitytests.However, regardless of construction design Clause 18.1.4 of the standard requires all temporary lightingstrings provided with metal guards to have the guard bonded to the equipment gr

10、ounding conductor(EGC). This is to further mitigate the potential risk of electric shock even during relamping when the guardcould inadvertently become energized from an exposed screwshell. The standard did not anticipate newconstructions of temporary lighting strings with non-replaceable LEDs where

11、 a metallic lamp guard maybe provided as a decorative feature only.UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULThe Canadian standards for portable luminaires CSA C22.2 No. 250.4, which also covers temporarylighting strings, and the US stan

12、dard for portable luminaires ANSI/UL 153 both have provisions to allowaccessible non-current carrying parts that are suitably insulated and not likely to become energized to beprovided without being bonded to the EGC.An equivalent provision is needed in ANSI/UL 1088 / CAN/ULC-S1088 to accommodate ex

13、posed metalparts of temporary lighting strings that are unlikely to contact live parts under any condition of use,including during installation and servicing.This proposal is intended to accommodate such temporary lighting string designs while maintaining thesame level of safety anticipated for meta

14、l guards of temporary lighting strings employing Edison screwbase lampholders.The revision to 4.2.5.2.3 corrects a discrepancy between the stated minimum distance of 365.8 mm thatmust exist between convenience receptacles and the equivalent value of 12 ft. shown in parenthesis. Therequirement was in

15、troduced in the 15th Edition of UL 48 to align with section 210.52(A)(1) of the NEC thatpermits up to 12 feet of space horizontally between receptacles along a floor line (i.e. 6 ft. in eitherdirection from a center point). However the stated value of 365.8 mm does not convert to 12 ft. Addingthe co

16、rrect metric value of 3.66 m will correct this discrepancy.The revisions to 4.3.5.1.3 and 4.3.5.2.2 will fix the cross-reference paragraph numbers to point the correctmarkings for dedicated and convenience receptacles in section 7 of the standard.Copyright 2018 UL LLCUL LLC, in performing its functi

17、ons 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 UL LLC. in practically applying therequirements of the s

18、tandard. They do not represent formal interpretations of the standard underAmerican National Standards Institute (ANSI) processes. UL LLC shall not be responsible to anyone forthe use of or reliance upon Certification Requirement Decisions by anyone. UL LLC shall not incur anyobligation or liability

19、 for damages, including consequential damages, arising out of or in connection withthe use or reliance upon Certification Requirement Decisions. The electronic version of the CertificationRequirement 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 1088 -2-