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): MDSTStandard Number: UL 574Standard Title: Standard for Electric Oil HeatersEdition Date: August 14, 2003Edition Number: 8Section / Paragraph Reference: Sect
3、ions 9 and 26Subject: Subdivided circuits for heating elementsDECISION:(New text is underlined, deleted text is indicated by strikethrough)9 Overload Protection9.1 A fuseholder or circuit breaker provided as a part of a heater shall not be accessible from the outsideof the oil heater without opening
4、 a door or cover, except that the operating handle of a circuit breaker mayproject outside of the enclosure. A plug-fuseholder shall be installed so that uninsulated live parts otherthan the screw shell and center contact will not be exposed to contact by persons removing or replacingfuses.9.2 An oi
5、l heater rated more than 48 amperes and employing resistance heating elements shall have theheating elements on subdivided circuits. Each subdivided load shall not exceed 48 amperes and shall beprotected at no more than 60 amperes.Exception: An oil heater employing a resistance type immersion electr
6、ic heating element contained in avessel marked with an appropriate ASME symbol may be subdivided into circuits not exceeding 120amperes and protected at no more than 150 amperes.9.3 The overcurrent protection devices required in 9.2 shall be provided by the manufacturer as an integralpart of the oil
7、 heater or shall be provided by the manufacturer as a separate assembly for independentmounting for use with the oil heater. When the overcurrent protection devices are provided as a separateassembly, the oil heater and the overcurrent protection assembly shall be marked as required in 26.14and 26.1
8、5, respectively.9.4 The overcurrent protection specified in 9.2 and 9.3 shall be of a type rated for branch circuit protection.A cartridge fuse used for this purpose shall be a Class CC, G, H, J, K, R, T, or equivalent fuse meetingthe requirements for branch circuit protection. A plug fuse shall be
9、used only in circuits of 125 voltsmaximum.MARKING26.14 When required overcurrent protective devices are provided as a separate assembly in accordancewith 9.3, the oil heater shall be permanently marked to indicate that it is to be used only with this separateassembly. For example: This oil heater is
10、 to be used only with (manufacturers identification) Model (orCatalog) _ overcurrent protection assembly.UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM UL26.15 The separate overcurrent assembly shall be permanently marked, where readily visible
11、 afterinstallation, with the name or identifying symbol of the manufacturer, the model or catalog number, andthe electrical rating.RATIONALE FOR DECISION:This Certification Requirement Decision is intended to document the safety requirements for theovercurrent protection for the heating elements use
12、d within ANSI/UL 574. This decision is consistent withsimilar UL Standards, such as UL 1453, and the NEC requirements for overcurrent protection ofresistance elements.Copyright 2013 Underwriters Laboratories Inc.UL, in performing its functions in accordance with its objectives, does not guarantee or
13、 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 applying the requirements of the standard. They do not represent formal
14、 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 incurany obligation or liability for damages, including consequential damages
15、 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 574 -2-
