UL-248W-BULLETINS-2006.pdf

FOR INTERNAL UL OR CSDS USE ONLY NOT FOR OUTSIDE DISTRIBUTION Subject 248W (4248-11) May 26, 2006 SUMMARY OF TOPICS The UL 4248-11 standard is the Part 11 of a harmonized trinational set of standards developed to complement the harmonized trinational UL 248 series of standards in that it consists of a Part 1 containing General Requirements applicable to all fuseholders and 8 subsequent Parts specifi c to a corresponding single Class of fuseholder. This bulletin supersedes the bulletin dated May 19, 2006. STP BALLOTS DUE: July 31, 2006 COMMENTS DUE: July 31, 2006 1. The UL 4248-11 standard is the Part 11 of a harmonized trinational set of standards developed to complement the harmonized trinational UL 248 series of standards in that it consists of a Part 1 containing General Requirements applicable to all fuseholders and 8 subsequent Parts specifi c to a corresponding single Class of fuseholder. BACKGROUND The UL 4248 family of Standards has been developed primarily to provide a tri-nationally harmonized (United States, Canada and Mexico) set of requirements for fuseholders. The UL 4248 series of Standards has been designed to complement the UL 248 family of Standards in that it consists of a Part 1 containing General Requirements applicable to all fuseholders and 8 subsequent Parts specifi c to a corresponding single Class of fuseholder. RATIONALE The actual technical requirements; Construction, Performance and Marking remain fundamentally the same as those contained in UL 512, upon which the UL 4248 family is based. There are, however, some technical differences that have been incorporated into these Standards. These include: The exclusive use of dummy fuses, in lieu of actual fuses, in the performance testing of fuseholders. The use of dummy fuses will increase the consistency of test results by removing the effects of fuse-to-fuse performance variations. The provision of requirements for the use of polymeric materials in the construction of fuseholders. The requirement of a 5 ma. limit for leakage current through an open fuse indicator or indicating circuit. Provision of a mechanism for the evaluation of the degree of electric shock protection provided by fuseholders marked with IP codes. Copyright Underwriters Laboratories Inc. Provided by IHS under license with ULLicensee=Army Northwestern Div./7838506130 Not for Resale, 08/29/2006 22:01:18 MDTNo reproduction or networking permitted without license from IHS -,-,- FOR INTERNAL UL OR CSDS USE ONLY NOT FOR OUTSIDE DISTRIBUTION PROPOSAL 1 General This Part is intended to be read together with the Standard for Fuseholders Part 1: General Requirements hereafter referred to as Part 1. The numbering of the Clauses in this Part corresponds to like numbered Clauses in Part 1. The requirements of Part 1 apply unless modifi ed by this Part. For Clauses not shown below, refer to the Standard for Fuseholders Part 1: General Requirements, NMX-J-009-4248-ANCECSA C22.2 No. 4248.1UL 4248-1. 1.1 Scope 1.1.2 These requirements cover: a) fuseholders intended for use with Type C (Edison-base) and Type S Plug Fuses as described in NMX-J-009/248/11-2000-ANCE, CSA C22.2 No. 248.11, UL 248-11, Low-Voltage Fuses Part 11: Plug Fuses; b) devices intended to be added to Edison-base fuseholders to reject fuses with larger ampere ratings; and c) devices intended to adapt Type S plug fuses for use in Edison-base fuseholders. 4 Classifi cation 4.1 Plug fuse fuseholders have a short-circuit withstand rating of 10,000 A. Plug fuse fuseholders are rated 250 V or less, and may be of Edison-base or Type S base design. 5 Characteristics 5.1 Summary of characteristics 5.1.3 Voltage and current rating 5.1.3.1 Plug fuse fuseholders shall be rated 125, 127, or 250 V. 5.1.3.2 Plug fuse fuseholders shall be rated 15, 20, or 30 A. MAY 26, 2006SUBJECT 248W-2- Copyright Underwriters Laboratories Inc. Provided by IHS under license with ULLicensee=Army Northwestern Div./7838506130 Not for Resale, 08/29/2006 22:01:18 MDTNo reproduction or networking permitted without license from IHS -,-,- FOR INTERNAL UL OR CSDS USE ONLY NOT FOR OUTSIDE DISTRIBUTION 5.1.4 Withstand rating 5.1.4.1 Plug fuse fuseholders shall have a short-circuit withstand rating of a 10,000 A. 6 Marking 6.1 Marking of fuseholder 6.1.1.1 In addition to the requirements of Part 1, Clauses 6.1.1.2 and 6.1.1.3 shall apply. 6.1.1.2 The marked current rating of a Type S fuseholder shall be located so that it will be plainly visible after installation. 6.1.1.3 A Type S adapter need not be marked with a withstand rating if the smallest unit package is marked Withstand Rating 10,000 rms amperes when installed in an Edison-base fuseholder marked 10,000 rms amperes. 7 Construction 7.4 Current-carrying parts 7.4.1 Except for plated No. 10 and larger wire-binding screws and nuts and stud terminals, iron or steel, plain or plated, shall not be used for parts that are depended upon to carry current. A plated iron or steel washer may be used under the center contact of an Edison-base plug fuseholder. 7.4.2 In a plug-fuseholder assembly intended for the connection of 15 A branch circuits, the ampacity of bus bars shall be as specifi ed in Table 7.4A. Table 7.4A Minimum ampacity of bus bars Total number of fuses per ungrounded bus bara Minimum ampacity 2-wire mains125 250 V, 3-wire mains3-phase, 4-wire mains 2303030 3353331 4484240 56650 66660 7 or 884 9 or 10100 11 or 12120 a For an assembly that has an unequal number of fuses per ungrounded bus bar, calculations shall be based on the larger number of fuses per ungrounded bus bar. MAY 26, 2006SUBJECT 248W-3- Copyright Underwriters Laboratories Inc. Provided by IHS under license with ULLicensee=Army Northwestern Div./7838506130 Not for Resale, 08/29/2006 22:01:18 MDTNo reproduction or networking permitted without license from IHS -,-,- FOR INTERNAL UL OR CSDS USE ONLY NOT FOR OUTSIDE DISTRIBUTION 7.6 Contacts of a cartridge fuseholder This section of Part 1 is not applicable to plug fuse fuseholders. The following requirements replace this section of Part 1. 7.6.1 Screw shells of Edison-base plug fuseholders 7.6.1.1 The thickness of the screw shell of a plug fuseholder, measured on the fl at surface of the bottom of the shell, shall not be less than 0.30 mm (0.012 in). 7.6.1.2 The screw shell of a plug fuseholder shall be made of copper or copper alloy. Aluminum or an aluminum alloy shall not be used. 7.6.1.3 A screw shell shall be of the medium-base size and shall, when tested with gauges made in conformity with the American National Standard Dimensions for Rolled Threads for Screw Shells of Electric Lampholders and for Screw Shells of Unassembled Lamp Bases, ANSI C81.1, go and not go as applicable. 7.6.1.4 The distance between the center contact and the plane of the edge of the insulation material surrounding the screw shell of a plug fuseholder, dimension K in Figure 7.6A, shall not be less than 19.1 mm (0.750 in) nor more than 20.6 mm (0.812 in). The distance between the center contact and the plane of the outer edge of the screw shell, dimension L, shall not be less than 14.3 mm (0.562 in) nor more than 17.5 mm (0.687 in). In a fuseholder with a spring-type center contact, the dimensions K and L shall be measured with the contact fully depressed. There shall not be fewer than two full threads in the metal screw shell beginning at the plane of the outer edge 7.6.1.5 A fuseholder may employ a female member of special design not necessarily of the screw shell type if it complies with the requirements in Clauses 7.6.1.3 and 8.7A, and if it has been found to be acceptable for the purpose by other appropriate tests, which may include temperature and short-circuit tests. This is generated text for fi gtxt. MAY 26, 2006SUBJECT 248W-4- Copyright Underwriters Laboratories Inc. Provided by IHS under license with ULLicensee=Army Northwestern Div./7838506130 Not for Resale, 08/29/2006 22:01:18 MDTNo reproduction or networking permitted without license from IHS -,-,- FOR INTERNAL UL OR CSDS USE ONLY NOT FOR OUTSIDE DISTRIBUTION 7.7 Creepage and clearance 7.7.1 Creepage and clearance spacings of a plug fuseholder shall be as specifi ed in Table 7.7A, except spacings: a) between adjacent screw shells of Edison-base plug fuseholders that are protected by surrounding walls of insulating material; b) between parts of the upper-contactor rings of adjacent Type S plug fuseholders; and c) between such screw shells or upper-contact-ring parts and a metal cover plate shall not be less than 6.4 mm (0.250 in) if the depth of the receptacle, as measured from the top of the wall to the plane of the center contact, is not less than 19.1 mm (0.750 in). Note: Spacings not less than 6.4 mm (0.250 in) through air and over surface from live parts to grounded dead metal are acceptable for plug fuseholders intended for use in appliances in which such spacings would comply with the requirements for the appliance involved. Figure 7.6A Dimensions of an assembled plug fuseholder Note: For dimensions of K and L, see Clause 7.6.1.4. MAY 26, 2006SUBJECT 248W-5- Copyright Underwriters Laboratories Inc. Provided by IHS under license with ULLicensee=Army Northwestern Div./7838506130 Not for Resale, 08/29/2006 22:01:18 MDTNo reproduction or networking permitted without license from IHS -,-,- FOR INTERNAL UL OR CSDS USE ONLY NOT FOR OUTSIDE DISTRIBUTION Table 7.7A Minimum acceptable spacings in a plug fuseholder Voltage involvedMinimum spacings, mm (in) a Between uninsulated live parts of opposite polarityBetween uninsulated live parts and grounded dead metal, through air or over surface Through airOver surface 12512.7 (0.5)19.1 (0.750)12.7 (0.5) 25019.1 (0.750)31.8 (1.250)12.7 (0.5) a An isolated dead metal part, such as a screwhead or washer, interposed between uninsulated live parts of opposite polarity or between an uninsulated live part and grounded dead metal is considered to reduce the spacing by an amount equal to the dimension of the interposed part along the path of measurement. 7.8A Type S plug fuseholders and adapters 7.8A.1 General 7.8A.1.1 The construction of a Type S fuseholder and adapter shall be such that a fuse other than a Type S fuse cannot be used in a fuseholder or adapter intended for a Type S fuse. 7.8A.1.2 A Type S fuse rated more than 15 A shall not be usable with a Type S fuseholder or adapter rated 15 amperes. 7.8A.1.3 A Type S fuse rated more than 20 A shall not be usable with a Type S fuseholder or adapter rated 20 amperes. 7.8A.1.4 There shall be no live parts exposed when a Type S fuse and fuseholder are installed and assembled together. 7.8A.1.5 Just below the upper contact ring of a Type S fuseholder and/or adapter, there shall be a hardened-steel ring, as illustrated in Figure 7.8A, that is protected against corrosion by a metallic-plated coating. This ring shall provide approximately one complete female thread for engagement with the threaded portion of a fuse body, the pitch of the thread shall be the same as that of the threads in the molded insulating material, and the apex of the thread shall be serrated. 7.8A.1.6 A 20-ampere fuseholder and/or adapter shall incorporate a contact-rejection member such as a cup, either integral with the contact or secured under the contact, or a spacer. The dimensions of the fuseholder shall be as specifi ed in Figure 7.8B with reference to this feature, and the cup or spacer shall be secured by means that will prevent its being readily removed. 7.8A.1.7 When tested with gauges based on the dimensions given in Figure 7.8A, a Type S fuseholder and/or adapter shall “go” and “no go” as applicable. See Figure 8.4A for gauge dimensions. MAY 26, 2006SUBJECT 248W-6- Copyright Underwriters Laboratories Inc. Provided by IHS under license with ULLicensee=Army Northwestern Div./7838506130 Not for Resale, 08/29/2006 22:01:18 MDTNo reproduction or networking permitted without license from IHS -,-,- FOR INTERNAL UL OR CSDS USE ONLY NOT FOR OUTSIDE DISTRIBUTION 7.8A.2 Fuseholders 7.8A.2.1 The dimensions of a Type S fuseholder shall be as specifi ed in Figure 7.8A. This is generated text for fi gtxt. MAY 26, 2006SUBJECT 248W-7- Copyright Underwriters Laboratories Inc. Provided by IHS under license with ULLicensee=Army Northwestern Div./7838506130 Not for Resale, 08/29/2006 22:01:18 MDTNo reproduction or networking permitted without license from IHS -,-,- FOR INTERNAL UL OR CSDS USE ONLY NOT FOR OUTSIDE DISTRIBUTION Figure 7.8A Dimensions of a Type S fuseholder, mm (in)a A Fuseholder B Details of threads aConversion Factor: 1 in = 25.4 mm MAY 26, 2006SUBJECT 248W-8- Copyright Underwriters Laboratories Inc. Provided by IHS under license with ULLicensee=Army Northwestern Div./7838506130 Not for Resale, 08/29/2006 22:01:18 MDTNo reproduction or networking permitted without license from IHS -,-,- FOR INTERNAL UL OR CSDS USE ONLY NOT FOR OUTSIDE DISTRIBUTION 7.8A.3 Adapters 7.8A.3.1 The male screw shell of an adapter shall be formed from a copper alloy not less than 0.20 mm (0.008 in) thick. Note: A screw shell formed from metal nominally 0.20 mm (0.008 in) thick may be thinner after forming due to commercial tolerances in the thickness of metal and the possible deformation of the metal during the forming, but the minimum thickness measured on the bottom or fl at portion of the shell shall not be less than 0.165 mm (0.0065 in). 7.8A.3.2 The male screw shell shall be of the medium-base size and shall, when tested with gauges made in conformity with the ANSI C81.1, American National Standard Dimensions for Rolled Threads for Screw Shells of Electric Lampholders and for Screw Shells of Unassembled Lamp Bases, “go” and “no go” as applicable. 7.8A.3.3 A locking device provided as a part of a Type S adapter shall be designed so that the adapter cannot be removed after it has been installed in an Edison-base plug fuseholder. The design of a locking device is not specifi ed. 7.8A.3.4 The dimensions of a Type S adapter shall be as specifi ed in Figure 7.8B. 7.8A.3.5 The marked current rating of a Type S adapter shall be located so that it will be plainly visible after the adapter is installed in an Edison-base fuseholder. This is generated text for fi gtxt. MAY 26, 2006SUBJECT 248W-9- Copyright Underwriters Laboratories Inc. Provided by IHS under license with ULLicensee=Army Northwestern Div./7838506130 Not for Resale, 08/29/2006 22:01:18 MDTNo reproduction or networking permitted without license from IHS -,-,- FOR INTERNAL UL OR CSDS USE ONLY NOT FOR OUTSIDE DISTRIBUTION Figure 7.8B Dimensions of