1、UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULAUGUST 29, 20141UL 1953Outline of Investigation for Power Distribution BlocksIssue Number: 5August 29, 2014Summary of TopicsThis Fifth issue of the Outline of Investigation for Power Distribution
2、Blocks , UL 1953, dated August 29, 2014 replaces the fifth issue publishedon August 19, 2014. The August 29, 2014 issue includes an editorialcorrection in Table 8.1, which increased the voltage limit maximum from600 to 1000 volts.ULs Outlines of Investigation are copyrighted by UL. Neither a printed
3、 norelectronic copy of an Outline of Investigation should be altered in any way. All ofULs Outlines of Investigation and all copyrights, ownerships, and rights regardingthose Outlines of Investigation shall remain the sole and exclusive property of UL.COPYRIGHT 2014 UNDERWRITERS LABORATORIES INC.UL
4、COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULAUGUST 29, 2014UL 19532No Text on This PageUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULCONTENTSINTRODUCTION1 Scope .52 Glossary .53 Units
5、 of Measurement .64 Updated References 65 Components 6CONSTRUCTION6 Materials .66.1 Current-carrying parts .66.2 Insulation .77 Terminal Assemblies 77.1 General .77.2 Tightening torque .97.3 Minimum size of conductor for line side service applications .98 Spacings 108.1 General 108.2 Insulating barr
6、iers .118.3 Insulating Covers 12PERFORMANCE9 General .1210 Temperature Test .1411 Dielectric Voltage-Withstand Tests 1511.1 General .1511.2 Clamped insulating joint .1511.3 Insulating barriers 1612 Strength of Insulating Base and Support Test 1613 Short-Circuit Current Test 16RATINGS14 General 1715
7、Short-Circuit Current 17MARKINGS16 General 1717 Connectors 1818 Short Circuit Current 1919 Insulating Covers .2019.1 General .2019.2 Use on line side of service equipment 2020 Permanence of Marking .20AUGUST 29, 2014 UL 1953 3UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBU
8、TION WITHOUT PERMISSION FROM ULAPPENDIX AStandards for ComponentsA1AUGUST 29, 2014UL 19534UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULINTRODUCTION1 Scope1.1 These requirements cover power distribution blocks that are rated 1000 volts or le
9、ss and intended tobe used on either the line side or load side of service equipment in accordance with the National ElectricalCode, NFPA 70. These blocks are used for splicing and tapping conductors in order to distribute powerto separate circuits or loads.1.2 A power-distribution block consists of
10、one or more connectors mounted on an insulating base. Eachconnector has provision for one or more incoming conductors and multiple tap-off conductors. A tap-offconductor is of the same or smaller size as the incoming conductor. The connectors may be of the lay-inconstruction which do not require the
11、 incoming conductor to be terminated.1.3 A power distribution block is intended to permanently support and insulate the wire terminations andjoints of each polarity from each other, and from the surface on which the power distribution block ismounted. A power distribution block may also be provided
12、with an insulating cover.1.4 These requirements do not cover terminal blocks which are covered by the Standard for TerminalBlocks, UL 1059.2 Glossary2.1 The following definitions apply in this Outline of Investigation.2.2 POWER DISTRIBUTION BLOCK A rigidly mounted device consisting of an insulating
13、base withbarriers having one or more electrically isolated terminal assemblies. Each terminal assembly serves asa junction to electrically connect two or more conductors.2.3 CONNECTOR A device that establishes the connection between one or more conductors in thefield as specified in the National Ele
14、ctrical Code, NFPA 70.2.4 TERMINAL ASSEMBLY A single pole of the power distribution block consisting of one or moreconnectors.AUGUST 29, 2014 UL 1953 5UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM UL3 Units of Measurement3.1 The values given i
15、n SI (metric) units shall be normative except for AWG/kcmil conductor sizes. Anyother values are for information only.4 Updated References4.1 Any undated reference to a code or standard appearing in the requirements of this Outline ofInvestigation shall be interpreted as referring to the latest edit
16、ion of that code or standard.5 Components5.1 Except as indicated in 5.2, a component of a product covered by this Outline of Investigation shallcomply with the requirements for that component. See Appendix A for a list of standards coveringcomponents generally used in the products covered by this Ou
17、tline of Investigation.5.2 A component need not comply with a specific requirement that:a) Involves a feature or characteristic not needed in the application of the component in theproduct covered by this outline, orb) Is superseded by a requirement in this outline.5.3 A component shall be used in a
18、ccordance with its recognized rating established for the intendedconditions of use.5.4 Specific components are recognized as being incomplete in construction features or restricted inperformance capabilities. Such components are intended for use only under limited conditions, such ascertain temperat
19、ures not exceeding specified limits, and shall be used only under those specific conditionsfor which they have been recognized.CONSTRUCTION6 Materials6.1 Current-carrying parts6.1.1 A current-carrying part intended for use with copper wire shall be of copper or a copper alloy.6.1.2 A current-carryin
20、g part intended for use with aluminum wire shall be of aluminum, an aluminumalloy, copper, or a copper alloy and shall be coated with an electrically conductive coating such as tin thatinhibits oxidation and corrosion.AUGUST 29, 2014UL 19536UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUC
21、TION ORDISTRIBUTION WITHOUT PERMISSION FROM UL6.2 Insulation6.2.1 A polymeric material used as part of a power distribution block shall comply with requirements inthe Standard for Polymeric Materials Use in Electrical Equipment Evaluations, UL 746C.6.2.2 An insulating material used as direct or indi
22、rect support of an uninsulated live part rated greater than600 volts shall comply with 6.2.1 and the Inclined Plane Tracking Test specified in the Standard forPolymeric Materials Short Term Property Evaluations, UL 746A. The insulating material shall not trackbeyond one inch in less than 60 minutes
23、using the time to track method. The voltage for the Inclined PlaneTracking Test shall be not less than the rated voltage of the equipment6.2.3 A live screw head, rivet, or nut on the underside of a base intended for surface mounting shall becountersunk not less than 1/8 inch (3.2 mm) in the clear, a
24、nd covered to a depth of not less than 1/8 inchwith a waterproof, insulating, sealing compound that will not soften at a temperature of 90C (194F) asdetermined by the test for softening point by the ball pressure test in the Standard for Polymeric Materials Short Term Property Evaluations, UL 746A.E
25、xception No. 1: The test is not required for a thermosetting material.Exception No. 2: A sealing compound is not required if the screw or nut is prevented from loosening by:a) Being staked or upset;b) A lock washer or;c) Other means;and is insulated from the mounting surface by material other than s
26、ealing compound or is provided withspacings complying with Table 8.1.7 Terminal Assemblies7.1 General7.1.1 A power distribution block shall be provided with one or more connectors. Each connector shall berated for a field installed conductor that is sized in accordance with Table 7.1.AUGUST 29, 2014
27、 UL 1953 7UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULTable 7.1Ampacity of insulated conductorsWire size 60C (140F) ampacitiesa,c75C (167F) ampacitiesaAWG or MCM (mm2) Copper Aluminum Copper Aluminum14 (2.1) 20 20 12 (3.3) 25 20 25 2010 (5
28、.3) 30 25 35 308 (8.4) 40 30 50 406 (13.3) 55 40 65 504 (21.2) 70 55 85 653 (26.7) 85 65 100 752 (33.6) 95 75 115 901 (42.4) 110 85 130 1001/0b(53.5)b150 1202/0b(67.4)b175 1353/0b(85.0)b200 1554/0b(107)b230 180250b(127)b255 205300b(152)b285 230350b(177)b310 250400b(203)b335 270500b(253)b380 310600b(
29、304)b420 340700b(355)b460 375750b(380)b475 385800b(405)b490 395900b(456)b520 4251000 (506) 545 4451250 (633) 590 4851500 (760) 625 5201750 (887) 650 5452000 (1013) 665 560NOTE These values of ampacity are based on a maximum of three current carrying conductors being field installedin a single condui
30、t.aThe numbers 60C (140F) and 75C (167F) indicate the conductor temperature rating.bFor a parallel conductor connector, the ampacity value is to be multiplied by the number of conductors that theconnector will accommodate 1/0 AWG (53.5 mm2) and larger.cFor wire sizes 1/0 AWG and larger, it is assume
31、d that wire with a 75C (167F) temperature rating will be used.7.1.2 A connector shall comply with the requirements in the Standard for Wire Connectors, UL486A-486B or the Standard for Equipment Wiring Terminals for Use With Aluminum and/or CopperConductors, UL 486E, as appropriate, and with this Out
32、line of Investigation.7.1.3 A multi-conductor connector shall be capable of securing all conductors in the intended manner. Indetermining the number and size of conductors, it is assumed that parallel conductors will be of size 1/0AWG (53.5 mm2) and larger.AUGUST 29, 2014UL 19538UL COPYRIGHTED MATER
33、IAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM UL7.1.4 Connectors shall all be of the same type when intended to be used for conductors in parallel.7.1.5 A connector provided with a screw or nut for securing the conductors shall be located so that:a) It is accessi
34、ble for examination; andb) The connector can be tightened or wires removed without loosening or removing connectors,conductors, screws, or nuts in any other connector that is not secured by the screws or nutsbeing loosened or tightened.7.1.6 A connector intended for use with stranded wire shall be s
35、uch that all strands of the conductor areconfined. The clamping movement alone shall adapt the connector for use with a stated range of wiresizes without permanent removal or addition of parts, if such use is intended.7.1.7 There shall be no sharp edges or corners that can damage conductor insulatio
36、n with which it maycome in contact.7.1.8 A connector that is intended to secure a copper wire and an aluminum wire simultaneously shall besuch that there will be no direct physical contact between the wires of different metals.7.2 Tightening torque7.2.1 The tightening torque for a connector shall no
37、t be less than 90 percent nor more than 100 percentof the value for that wire size corresponding to the ampere rating of the connector as specified and testedin the Standard for Wire Connectors, UL 486A-486B or the requirements for Equipment Wiring Terminalsfor Use With Aluminum and/or Copper Conduc
38、tors, UL 486E. See 17.10.Exception: The torque value of the connector may be less than 90 percent if the connector complies withUL 486A-486B or UL 486E at the lesser assigned torque value.7.3 Minimum size of conductor for line side service applications7.3.1 A power distribution block rated for use o
39、n the line side of the service shall be capable ofaccommodating a minimum size 8 AWG (8.4 mm2) copper conductor. The power distribution block shallalso accommodate a minimum size 6 AWG (13.3 mm2) aluminum conductor if the power distribution blockis marked for use with aluminum wire.AUGUST 29, 2014 U
40、L 1953 9UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM UL8 Spacings8.1 General8.1.1 The spacings of a power distribution block shall be as indicated in Table 8.1. The spacings togrounded dead metal includes spacings to the smallest size enclosu
41、re specified for the power distributionblock by the manufacturer and any dead metal that may be electrically connected to the enclosureincluding mounting hardware.Table 8.1Minimum acceptable spacingsVoltage involved Between uninsulated live parts of opposite polarity Between uninsulated live parts a
42、nd anygrounded dead metalGreaterthanMaximum Through air Over surface Through air Over surfacemm (in) mm (in) mm (in) mm (in)0 125 12.7 (1/2) 19.1 (3/4) 12.7 (1/2) 12.7 (1/2)125 250 19.1 (3/4) 31.8 (1-1/4) 12.7 (1/2) 12.7 (1/2)250 1000 25.4 (1) 50.8 (2) 25.4 (1) 25.4 (1)8.1.2 Spacings at connectors s
43、hall be measured with rated conductor(s) installed so as to produceminimum spacings.8.1.3 With respect to Table 8.1:a) An isolated dead metal part (such as a screw head or a washer) interposed betweenuninsulated live parts of opposite polarity or between an uninsulated live part and groundeddead met
44、al is considered to reduce the spacing by an amount equal to the dimension of theinterposed part along the path of measurement.b) In measuring an over surface spacing, any slot, groove, or the like, that is 0.33 mm (0.013in) wide or less in the contour of insulating material is to be disregarded.c)
45、In measuring spacings, an air space of 0.33 mm (0.013 in) or less between a live part andan insulating surface is to be disregarded, and the live part is to be considered in contact withthe insulating material.d) Spacings are measured through any cracks, joints or openings between an insulating cove
46、rand the base.8.1.4 A connector shall be prevented from turning to the extent that spacings would be reduced to lessthan those required in 8.1 and Table 8.1.Exception: A means to prevent turning need not be provided if minimum spacings are maintained whenconnectors are turned 30 degrees toward each
47、other or toward another uninsulated live or grounded metalpart.AUGUST 29, 2014UL 195310UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM UL8.1.5 Spacings shall be measured through cracks unless a clamped joint complies with the test describedin 11
48、.2. A clamped joint is a joint between two pieces of insulation that are under pressure as shown inFigure 8.1. Adhesives, cements, and the like, used to effect a seal in place of a tightly mated joint, shallcomply with the Standard for Polymeric Materials Use in Electrical Equipment Evaluations, UL
49、746C.This is generated text for figtxt.8.2 Insulating barriers8.2.1 In 8.2.2 8.2.5, the barrier referred to is insulating material that separates uninsulated live parts ofopposite polarity or separates an uninsulated live part from a grounded dead metal part (including theenclosure) if the through air spacing between the parts would otherwise be less than the minimumacceptable value specified in Table 8.1.8.2.2 Insulating material that provides the sole separation shall:a) Be a material rated for supporting an uninsulated live part; andb) Have a
