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): NYTTStandard Number: UL 2250Standard Title: Standard for Instrumentation Tray CableEdition Date: April 3, 2006Edition Number: 2Section / Paragraph Reference:
3、 17.1.1, 17.3.1 and 17.3.3Subject: Addition of Stainless Steel as a Welded and Corrugated Metal SheathDECISION:17 Metal Covering17.1 General17.1.1 Interlocked metal armor, or a continuous metal sheath is acceptable over the jacket on any cable.See tests in Crushing Test for Cable Marked for Direct B
4、urial, Section 30, Tension Test of InterlockedSteel or Aluminum Armor, Section 37, and Flexibility Test for Cable Having Interlocked Armor or a Smoothor Corrugated Metal Sheath, Section 38. Any metal covering that is provided shall be as follows:a) A smooth metal sheath shall comply with 17.1.2 and
5、17.2.1 - 17.2.3.b) A welded and corrugated metal sheath shall comply with 17.1.2, 17.1.3, 17.3.1, and 17.3.2,and 17.3.3.c) An extruded and corrugated metal sheath shall comply with 17.1.2, 17.1.3, 17.4.1, and17.4.2.d) Interlocked metal armor shall comply with 17.1.2 and 17.5.1 - 17.5.9.e) Wire armor
6、 or a metal braid applied over a jacket that complies with Cable Jacket, Section16.17.3.1 A welded and corrugated metal sheath shall be of an aluminum-base alloy having a copper contentof 0.40 percent or less, a stainless steel alloy having a chromium content of not less than 16 percent, acopper all
7、oy or a bronze alloy. The sheath shall be tightly formed around the underlying cable and shallbe welded and corrugated. See 17.2.3.17.3.3 In the case of stainless steel sheathed cables, any outer jacket compound and any cable jacket,binder, separator or insulation material coming in direct contact w
8、ith the stainless steel armor shall notcontain chlorine.RATIONALE FOR DECISION:UL 2250 currently permits a corrugated round cable to use armor made of a copper-alloy tube,bronze-alloy tube or an aluminum-alloy tube. When the standard was written, it was not anticipated thatcorrugated stainless steel
9、 armor would be used. Since this material is used to manufacture Electrical RigidMetal Conduit (UL 6A) and Liquid-Tight Flexible Metal Conduit (UL 360), and Metal Clad Cable-MCUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM UL(UL1569) this mater
10、ial is being proposed to be added as an alternate armor in UL 2250. In addition, wirearmor or a metal braid over a jacketed cable has been permitted in other Wire and Cable SafetyStandards. It is an optional construction that is permitted only on completely jacketed cables.Copyright 2015 Underwriter
11、s Laboratories Inc.UL, in performing its 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 Underwrit
12、ers Laboratories Inc. inpractically applying 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 Deci
13、sions by anyone. UL shall not incurany 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 2250 -2-
