1、UL 50ISBN 1-55989-909-3Enclosures for ElectricalEquipmentUnderwriters Laboratories Inc. (UL)333 Pfingsten RoadNorthbrook, IL 60062-2096UL Standard for Safety for Enclosures for Electrical Equipment, UL 50Eleventh Edition, Dated October 19, 1995Revisions: This Standard contains revisions through and
2、including September 12, 2003.Summary of TopicsThis revision to ANSI/UL 50 is being issued to update the Title Page to indicate approval as anAmerican National Standard.UL Standards for Safety are developed and maintained in the Standard Generalized Markup Language(SGML). SGML - an international stan
3、dard (ISO 8879-1986) - is a descriptive markup language thatdescribes a documents structure and purpose, rather than its physical appearance on a page. Due toformatting differences resulting from the use of ULs new electronic publishing system, please note thatadditional pages (on which no requireme
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5、an effective date noteindicating the date of publication or the date on which the changed requirement becomes effective.The revised requirements are substantially in accordance with ULs Bulletin(s) on this subject datedFebruary 13, 2003 and July 8, 2003. The bulletin(s) is now obsolete and may be di
6、scarded.The revisions dated September 12, 2003 include a reprinted title page (page1) for this Standard.As indicated on the title page (page 1), this UL Standard for Safety is an American National Standard.Attention is directed to the note on the title page of this Standard outlining the procedures
7、to be followedto retain the approved text of this ANSI/UL Standard.As indicated on the title page (page1), this UL Standard for Safety has been adopted by the Departmentof Defense.The master for this Standard at ULs Northbrook Office is the official document insofar as it relates to aUL service and
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10、 in a retrieval system, ortransmitted in any form by any means, electronic, mechanical photocopying, recording, or otherwisewithout prior permission of UL.Revisions of UL Standards for Safety are issued from time to time. A UL Standard for Safety is currentonly if it incorporates the most recently a
11、dopted revisions.SEPTEMBER 12, 2003 UL 50 tr1UL provides this Standard as is without warranty of any kind, either expressed or implied, including butnot limited to, the implied warranties of merchantability or fitness for any purpose.In no event will UL be liable for any special, incidental, consequ
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21、asing a UL Standard can make a copy of the page or pages beingviewed for their own fair and/or practical internal use.The requirements in this Standard are now in effect, except for those paragraphs, sections, tables, figures,and/or other elements of the Standard having future effective dates as ind
22、icated in the note following theaffected item. The prior text for requirements that have been revised and that have a future effective dateare located after the Standard, and are preceded by a SUPERSEDED REQUIREMENTS notice.New product submittals made prior to a specified future effective date will
23、be judged under all of therequirements in this Standard including those requirements with a specified future effective date, unlessthe applicant specifically requests that the product be judged under the current requirements. However, ifSEPTEMBER 12, 2003 UL 50tr2the applicant elects this option, it
24、 should be noted that compliance with all the requirements in thisStandard will be required as a condition of continued Listing, Recognition, Classification, and Follow-UpServices after the effective date, and understanding of this should be signified in writing.Copyright 2003 Underwriters Laborator
25、ies Inc.This Standard consists of pages dated as shown in the following checklist:Page Date1-3.September 12, 20034-6 .November 19, 19997-8B .September 12, 20039-10B .November 19, 199911.October 19, 199512-14B.November 19, 199915-16 .October 1, 199617-18B.November 19, 199919.October 1, 199620.October
26、 19, 199521-22 .November 19, 199923.October 19, 199524-24B .November 6, 199725-28 .November 19, 199928A-29 .October 1, 199630.October 19, 199531-32B .November 6, 199733-34.September 12, 200335-36B .November 6, 199737.October 19, 199538-40A.November 19, 199940B-41 .October 1, 199642.October 19, 19954
27、3 .September 12, 200344-47 .October 19, 199548.October 1, 199649.November 19, 199950.October 19, 199551.August 19, 199752.October 19, 199553-60 .November 19, 199961.October 1, 199662.October 19, 1995SA1-SA2 .October 19, 1995SEPTEMBER 12, 2003 UL 50 tr3SEPTEMBER 12, 2003 UL 50tr4No Text on This PageO
28、CTOBER 19, 1995(Title Page Reprinted: September 12, 2003)1UL 50Standard for Enclosures for Electrical EquipmentThe First and Second editions were titled Standard for Cabinets and CutoutBoxes. The Third Ninth editions were titled Standard for Cabinets and Boxes.First Edition March, 1916Second Edition
29、 March, 1929Third Edition February, 1941Fourth Edition May, 1956Fifth Edition November, 1962Sixth Edition October, 1970Seventh Edition June, 1975Eighth Edition April, 1980Ninth Edition September, 1988Tenth Edition July, 1992Eleventh EditionOctober 19, 1995The most recent designation of ANSI/UL 50 as
30、 an American National Standard(ANSI) occurred on August 19, 2003.This ANSI/UL Standard for Safety, which consists of the Eleventh edition withrevisions through September 12, 2003, is under continuous maintenance,whereby each revision is ANSI approved upon publication. Comments orproposals for revisi
31、ons on any part of the Standard may be submitted to UL at anytime. Written comments are to be sent to UL-RTP Standard Department, 12Laboratory Dr., P.O. Box 13995, Research Triangle Park, NC, 27709-3995.The Department of Defense (DoD) has adopted UL 50 on April 5, 1982 . Thepublication of revised pa
32、ges or a new edition of this Standard will not invalidatethe DoD adoption.An effective date included as a note immediately following certain requirementsis one established by Underwriters Laboratories Inc.Revisions of this Standard will be made by issuing revised or additional pagesbearing their dat
33、e of issue. A UL Standard is current only if it incorporates themost recently adopted revisions, all of which are itemized on the transmittal noticethat accompanies the latest set of revised requirements.ISBN 1-55989-909-3COPYRIGHT 1988, 2003 UNDERWRITERS LABORATORIES INC.ANSI/UL 50-2003SEPTEMBER 12
34、, 2003ENCLOSURES FOR ELECTRICAL EQUIPMENT - UL 502No Text on This PageCONTENTSFOREWORD .6INTRODUCTION1 Scope .72 Glossary .73 References .8A4 Units of Measurement .8ACONSTRUCTIONGENERAL5 General .9ENCLOSURES6 General .107 Polymeric Enclosures/Parts .137.1 General .137.2 Bonding .147.3 Nonmetallic-sh
35、eathed cable clamps .157.4 Rigid nonmetallic conduit .157.5 Rigid metallic conduit .157.6 Provisions for support or mounting .158 Openings in Enclosures .158.1 General .158.2 Equipment openings .158.3 Drainage openings .168.4 Mounting openings .168.5 Conduit knockouts and conduit openings .178.6 Additional openings .179 Observation Windows .1810 Thickness of Cast-Metal Enclosures .1811 Thickness of Sheet-Metal Enclosures .1912 Joints and Fastenings .2113 Notches .2114 Gaskets .24BPROTECTION AGAINST CORROSION15 Outdoor Enclosures .
