1、UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULMarch 31, 20111SUBJECT 2745OUTLINE OF INVESTIGATIONFORMETER SOCKET ADAPTERS FOR COMMUNICATIONS EQUIPMENTIssue No. 1March 31, 2011Summary of TopicsThis is the first issue of the Outline of Investi
2、gation for Meter SocketAdapters for Communications Equipment, Subject 2745, which coverswireline and wireless communications devices, or power suppliespowering such devices, installed in a meter socket adapter. These devicesare associated with network communications equipment powered at thepremises
3、and may be associated with smart grid applications.COPYRIGHT 2011 UNDERWRITERS LABORATORIES INC.UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULMARCH 31, 2011SUBJECT 27452No Text on This PageUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER R
4、EPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULCONTENTSINTRODUCTION1 Scope .52 Units of Measurement .63 Undated References 64 Glossary .6CONSTRUCTION5 Components 76 Meter Socket Adapter .77 Enclosures .77.1 General .77.2 Nonmetallic enclosures 87.3 Covers 88 Internal Wiring and Connections 89
5、Accessibility 910 Separation of Circuits 911 Isolated Secondary Circuits 1012 Interconnection Circuits 1012.1 General .1012.2 Protection of communications circuit wiring 1113 Clearances, Creepage Distances Exception: A hinged cover is not required if the only overload-protective devices enclosed are
6、:1) Supplementary fuses in control circuits, provided the devices and circuit loads arewithin the same enclosure or2) Extractor fuses having an integral enclosure.b) If it is necessary to open the cover in connection with normal operation of the devicec) If it gives access to communications or power
7、 supply circuits that contain service ports(Ethernet, USB, SD slots, etc.), configuration mechanisms (DIP switches, etc.) or resetswitches.8 Internal Wiring and Connections8.1 The internal wiring shall consist of general use wire or appliance wiring material acceptable for theparticular application
8、when considered with respect to the temperature and voltage and conditions ofservice to which the wiring is likely to be subjected.8.2 Primary circuit wiring and any wiring insulation required to maintain double or reinforced insulationbetween primary and secondary circuits shall be rated minimum 13
9、0C.Exception: For equipment intended only for installation indoors and clearly marked in accordance with25.2, the wire may be rated 105C minimum. If the equipment specifications include a maximum operatingtemperature (maximum temperature or high end of a specified temperature range) then the minimum
10、 wiretemperature rating shall be the maximum specified temperature (C) + 65C but not less than 105C.8.3 Line voltage wiring that does not conduct the main current for the meter circuit (that is not connectedin series with the meter base jaws and meter blades) shall be no smaller than 18 AWG. Conduct
11、ors ofsizes 18 AWG and 16 AWG shall be permitted to be used, provided they supply loads that do not exceedthe ampacities given in the National Electrical Code, NFPA 70, Section 402.5 and do not exit the metercollar enclosure. Conductors larger than 16 AWG shall not supply loads greater than the ampa
12、cities givenin NFPA 70, Section 310.15. Overcurrent protection for conductors shall be provided in accordance withthe conductor ampacity described in NFPA 70, Section 240.4(D). It is permitted for the overcurrentprotection to be at the termination of the conductors provided the conductors are less t
13、han 12 inches longMARCH 31, 2011SUBJECT 27458UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULand are protected against physical damage by suitable routing, positioning, securing, double or reinforcedinsulation, jacketing, or other physical pro
14、tection means to reduce the risk of a fault occurring prior to theovercurrent protection.8.4 Current carrying parts that conduct the main current for the meter circuit shall comply with Standardfor Meter Sockets, UL 414.8.5 Wires within an enclosure, compartment, raceway, or the like shall be so pos
15、itioned or protected thatcontact with any rough, sharp, or movable part is prevented.8.6 Wiring and terminals shall be arranged, routed and secured so as to:a) Not interfere with the meter installation/connection, adjustment, removal or replacement andb) Reduce the possibility of wire damage, short
16、circuits or the reduction of creepage andclearances during or as a result of meter installation/connection, adjustment, removal orreplacement.8.7 All joints and connections shall be mechanically secure and shall provide effective electrical contactwithout strain on connections and terminals. Solder
17、connections shall be made mechanically secure priorto soldering.Exception: Wiring through openings on printed wiring boards need not be mechanically secure beforesoldering.8.8 A splice shall be provided with insulation equivalent to that of the wires involved if the requiredspacing between the splic
18、e and other metal parts is not permanently maintained.9 Accessibility9.1 The accessibility requirements in Section 2.1 of the Standard for Information Technology Equipment Safety Part 1: General Requirements, UL 60950-1 apply.10 Separation of Circuits10.1 Circuit conductors intended for connection t
19、o telephone communication, data communication, firealarm, antenna/cable or isolated secondary circuits, shall be provided with a barrier, physically secured bymeans other than friction, which separates the ac power circuit conductors from the conductors of theother circuits.Exception No. 1: A barrie
20、r is not required between conductors that are separated by a minimum spacingof 2 inches.Exception No. 2: Factory installed conductors that are acceptably insulated for the maximum ac powercircuit voltage involved need not be separated from the factory installed ac power circuit conductors,provided t
21、hat breakage or loosening of a conductor at a terminal in either circuit cannot result in contactbetween uninsulated live parts of one circuit and uninsulated or inadequately insulated live parts of theother circuit.MARCH 31, 2011 SUBJECT 2745 9UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPR
22、ODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM UL10.2 An optical isolator that is relied upon to provide basic or supplementary insulation as required by theStandard for Information Technology Equipment Safety Part 1: General Requirements, UL 60950-1shall comply with the Standard for Optical Isolat
23、ors, UL 1577, and shall have a rated dielectric isolationvoltage no less than the test voltage required by Section 5.2, Table 5C of UL 60950-1. The requiredwithstand voltage shall be determined by Annex G, Table G.1, “AC mains transient voltages” of UL60950-1, for overvoltage category IV.10.3 A powe
24、r switching semiconductor device that is relied upon to provide isolation between primarycircuits and ground shall be comply with the Standard for Electrically Isolated Semiconductor Devices, UL1557 and shall have a rated isolation voltage no less than 1000 V plus twice the circuit voltage to ground
25、.10.4 The output of current transformers shall be isolated from secondary circuits and limited powersources that are not contained wholly within the equipment. This isolation provided shall meet therequirements for double insulation based on the highest voltage of the circuits involved.11 Isolated S
26、econdary Circuits11.1 In addition to the requirements for Separation of Circuits, a secondary circuit shall comply with therequirements for Limited Power Sources in Section 2.5 of the Standard for Information TechnologyEquipment Safety Part 1: General Requirements, UL 60950-1.Exception: Isolated sec
27、ondary circuits evaluated as primary circuits need not comply with thisrequirement.12 Interconnection Circuits12.1 General12.1.1 Each interconnection circuit shall limit the voltage, current and power in accordance with 12.1.2and 12.1.3.12.1.2 Each interconnection circuit shall be one of the followi
28、ng types:a) A SELV Circuit; orb) A Limited Current Circuit; orc) A TNV-1 Circuit, TNV-2 Circuit or TNV-3 Circuit.12.1.3 Each interconnection circuit shall comply with the requirements for Class 2 circuits as defined inthe National Electrical Code, NFPA 70, Section 725.121, or for Limited Power Sourc
29、es in Section 2.5 ofthe Standard for Information Technology Equipment Safety Part 1: General Requirements, UL60950-1.MARCH 31, 2011SUBJECT 274510UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM UL12.2 Protection of communications circuit wiring12
30、.2.1 Equipment intended to provide power over a communications wiring system (such as twisted pairtelecommunications wiring or CAT 5, 5E, 6, etc. Ethernet cabling) to remote equipment shall limit theoutput current to a value that does not cause damage to the wiring system, due to overheating, under
31、anyexternal load condition. The maximum continuous current from equipment shall not exceed a current limitthat is suitable for the minimum wire gauge specified in the equipment installation instructions. The currentlimit is 1.3 A if such wiring is not specified.Note 1: The overcurrent protective dev
32、ice may be a discrete device such as a fuse, or a circuit thatperforms that function.Note 2: The minimum wire diameter normally used in telecommunication wiring is 0.4 mm, for which themaximum continuous current for a multi-pair cable is 1.3 A. This wiring is not usually controlled by theequipment i
33、nstallation instructions, since the wiring is often installed independent of the equipmentinstallation.Note 3: Further current limitations may be necessary for equipment intended for connection to networksthat are subject to overvoltages, due to operating parameters for protective devices.12.2.2 Com
34、pliance with 12.2.1 is checked as follows:a) If current limiting is due to the inherent impedance of the power source, the output currentinto any resistive load, including a short-circuit, is measured. The current limit shall not beexceeded after 60 s of test.b) If current limiting is provided by an
35、 overcurrent protective device having a specified time/current characteristic:1) The time/current characteristic shall show that a current equal to 110 percent of thecurrent limit will be interrupted within 60 min; andNote: A fuse rated1Aisconsidered to comply with the above limit.2) The output curr
36、ent into any resistive load, including a short-circuit, with theovercurrent protective device bypassed, measured after 60 s of test, shall not exceed 1000/U, where U is the output voltage measured with all load circuits disconnected.c) If current limiting is provided by an overcurrent protective dev
37、ice that does not have aspecified time/current characteristic:1) The output current into any resistive load, including a short-circuit, shall not exceedthe current limit after 60 s of test and2) the output current into any resistive load, including a short-circuit, with theovercurrent protective dev
38、ice bypassed, measured after 60 s of test, shall not exceed 1000/U, where U is the output voltage measured with all load circuits disconnected.MARCH 31, 2011 SUBJECT 2745 11UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM UL12.2.3 Where a fuse is
39、 used to provide current limiting in accordance with 12.2, it shall be accessible onlyto utility personnel unless it is not readily interchangeable with a fuse of a different rating.13 Clearances, Creepage Distances c) Creepage and clearance distances on printed wiring boards are evaluated as pollut
40、iondegree 2 when adjacent conductive material is covered by any coating, such as a solder mask,which provides an uninterrupted covering over at least one side and the complete distance upto the other side of conductive material;MARCH 31, 2011SUBJECT 274512UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR F
41、URTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULd) Creepage and clearance distances on printed wiring boards shall be evaluated as pollutiondegree 1 under one of the following conditions:1) A coating which complies with the requirements for Conformal Coatings in theStandard for Polymeri
42、c Materials Use in Electrical Equipment Evaluations, UL 746Cor2) At a specific printed wiring board location by application of at least a 1/32 inch (0.79mm) thick layer of silicone rubber or through potting, without air bubbles, in epoxy orpotting material.13.3 Insulating barriers13.3.1 An insulatin
43、g barrier required to maintain creepage, clearance or distance through insulationbetween primary circuits and ground or between primary and secondary circuits shall be rated mininum130C.Exception: For equipment intended only for installation indoors and clearly marked in accordance with25.2, the mat
44、erial may be rated 105C minimum. If the equipment specifications include a maximumoperating temperature (maximum temperature or high end of a specified temperature range) then theminimum material temperature rating shall be the maximum specified temperature (C) + 65C but notless than 105C.14 Groundi
45、ng and Bonding14.1 Parts to be grounded14.1.1 The following metallic parts shall be provided with a means to bond the parts to the meter socketenclosure to which the equipment connects:a) Metallic enclosures;b) Dead metal parts accessible during operation or servicing that are likely to becomeenergi
46、zed; andc) Other parts required to be grounded for safety purposes.14.1.2 With respect to 14.1.1(b), a part is likely to be energized if the part can come into contact with ahazardous part due to a single mechanical failure or the failure of basic or supplementary insulation. Apart is not considered
47、 likely to be energized if it is isolated from primary or hazardous voltage circuits bydouble or reinforced insulation.14.1.3 With respect to 14.1.1(c), one example of a part required to be grounded for safety purposes is aprotective ground shield used in an isolation transformer.MARCH 31, 2011 SUBJ
48、ECT 2745 13UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM UL14.2 Grounding connections14.2.1 Grounding/bonding connections shall be connected by a clamp, bolt, screw, braze, weld or anequivalent positive means that cannot be loosened from the o
49、utside. The grounding connection may alsoinclude a corrosion resistant strap or jumper. Mechanical connections shall be secured by means otherthan friction. A solder connection may be used if the grounding/bonding lead is mechanically secured tothe enclosure prior to soldering. The grounding/bonding connection shall penetrate nonconductivecoatings, such as paint or vitreous enamel.14.2.2 A grounding/bonding conductor shall be of copper, copper alloy, or other material that has beeninvestigated for use as an electrical conductor. A ferrous metal part in the
