1、UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULOctober 8, 20131UL 2851Outline of Investigation for Low-voltage Distribution Systems andEquipment for Desk and Similar Work-surface InstallationsIssue Number: 1OCTOBER 8, 2013Summary of TopicsThi
2、s first issue of the Outline of Investigation for Low-voltage DistributionSystems and Equipment for Desk and Similar Work-surface Installations,UL 2851, covers low voltage power distribution systems and equipmentintended for installation and use in dry locations, other than hazardous(classified), in
3、 accordance with the National Electrical Code (NEC), NFPA70.ULs Outlines of Investigation are copyrighted by UL. Neither a printed norelectronic copy of an Outline of Investigation should be altered in any way. All ofULs Outlines of Investigation and all copyrights, ownerships, and rights regardingt
4、hose Outlines of Investigation shall remain the sole and exclusive property of UL.COPYRIGHT 2013 UNDERWRITERS LABORATORIES INC.UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULOCTOBER 8, 2013UL 28512No Text on This PageUL COPYRIGHTED MATERIAL N
5、OT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULCONTENTSINTRODUCTION1 Scope .52 Components 63 Units of Measurement .64 Undated References 65 Glossary .6MECHANICAL CONSTRUCTION6 General 77 Assembly and Mounting .78 Metal Components 89 Polymeric Enclosure .810 Adhesives
6、 .9ELECTRICAL CONSTRUCTION11 General .912 Current-Carrying Parts 913 Securement of Components .914 Splices and Connections 1015 Electrical Spacings 1116 Class 2 Power Supplies and Transformers .1117 Low Voltage Equipment .1118 Switches and Controls .1219 Control Circuits .1220 Interconnecting System
7、 Cables and Connectors 1320.1 General .1320.2 Load connectors .13PERFORMANCE21 Connector Tests 1421.1 General .1421.2 Movable connector cycle conditioning and temperature test .1421.3 Field-installed conductors conditioning and temperature test .1521.4 Fixed connector cycling test .1522 System Tempe
8、rature Test .1622.1 General .1622.2 Test setup Low voltage interconnecting system 1822.3 Test setup Power supplies and low voltage equipment 1823 Mechanical Assembly Load Test 1824 Moment Test .1925 Mold Stress-Relief Distortion Test .1926 Dielectric Voltage Withstand Test .20OCTOBER 8, 2013 UL 2851
9、 3UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULMARKINGS27 General 2028 Connectors 2129 Correlation Markings 21INSTRUCTIONS30 General 2131 Operating Instructions .2332 Connectors 23APPENDIX A (NORMATIVE) Reference StandardsStandards for Comp
10、onentsA1OCTOBER 8, 2013UL 28514UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULINTRODUCTION1 Scope1.1 These requirements cover low voltage power distribution systems and equipment intended forinstallation and use in dry locations, other than h
11、azardous (classified), in accordance with the NationalElectrical Code (NEC), NFPA 70.1.2 The low voltage systems covered by this Outline are intended to be connected to a premises branchcircuit rated 600 V or less. A system consists of:a) A single supply connection to the premises branch circuit;b)
12、A power supply with Class 2 output(s) operating at 30 V ac (42.4 V peak) or less, or 60 V dcor less;c) Interconnecting system (such as a track, rail, conductors or cords) for connecting the Class 2source to low voltage equipment; andd) Low voltage equipment electrically connected to the interconnect
13、ing system.The system may also include AC convenience receptacles rated 125 or 250 V, 15 or 20 A, meeting thedimensional requirements of ANSI/NEMA WD 6, Wiring Device Dimensional Requirements.1.3 The low voltage systems covered by this Outline are typically intended for installation in or on worksur
14、faces such as desks in office environments (home or commercial). These requirements do not apply tolocations such as kitchen counters, bathrooms, or similar locations that involve use near plumbing fixturesor heating surfaces.1.4 This Outline does not apply to systems covered by the Standard for Sus
15、pended Ceiling Grid LowVoltage Systems and Equipment, UL 2577.1.5 This Outline does not apply to systems covered by the Standard for Furniture Power DistributionUnits, UL 962A. However, this Outline may supplement UL 962A.OCTOBER 8, 2013 UL 2851 5UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER RE
16、PRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM UL2 Components2.1 Except as indicated in 2.2, a component of a product covered by this Outline shall comply with therequirements for that component. See Appendix A for a list of standards covering components used in theproducts covered by this standa
17、rd.2.2 A component is not required to comply with a specific requirement that:a) Involves a feature or characteristic not required in the application of the component in theproduct covered by this Outline; orb) Is superseded by a requirement in this Outline.2.3 A component shall be used in accordanc
18、e with its rating established for the intended conditions ofuse.2.4 Specific components are incomplete in construction features or restricted in performance capabilities.Such components are intended for use only under limited conditions, such as certain temperatures notexceeding specified limits, an
19、d shall be used only under those specific conditions.3 Units of Measurement3.1 Values stated without parentheses are the requirement. Values in parentheses are explanatory orapproximate information.3.2 Unless otherwise indicated, all voltage and current values mentioned in this Outline areroot-mean-
20、square (rms).4 Undated References4.1 Any undated reference to a code or standard appearing in the requirements of this Outline shall beinterpreted as referring to the latest edition of that code or standard.5 GlossaryFor the purpose of this Outline, the following definitions shall apply.5.1 BUS BAR
21、A non-insulated conductor electrically connected to the low voltage source of supplyand physically supported by an insulator. The bus bar provides a power rail for connection of the lowvoltage equipment.5.2 CONNECTOR A generic term used to refer to an electro-mechanical fitting:a) Power Feed Connect
22、or An electro-mechanical connector used to connect either the outputfrom the Class 2 power supply to a power distribution cable, or directly to the bus bar, or fromthe power distribution cable to the bus bar.b) Load Connector An electro-mechanical connector used to tap power from the bus bar tothe l
23、ow voltage equipment.5.3 INVERSE POLARITY PROTECTION A system that prevents two interconnected Class 2 powersupplies, when connected positive to negative, from allowing current to flow from one power source intothe second power source.OCTOBER 8, 2013UL 28516UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR
24、 FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM UL5.4 LOW VOLTAGE INTERCONNECTING SYSTEM The wiring, rail, or similar components that aresupplied from the Class 2 source, and intended for connection of the low voltage equipment specifiedby the manufacturer.5.5 MOUNTING MEANS Hardware (s
25、uch as screws or clips) provided for mechanically securing thelow voltage interconnecting system or low voltage equipment to the furnishing.5.6 POWER SUPPLY A Class 2 power conversion unit connected between the branch circuit powerdistribution system and the low voltage system.5.7 TERMINAL, WIRE-BIN
26、DING SCREW A terminal in which a single conductor is clamped directlyunder the head of the screw when it is tightened.MECHANICAL CONSTRUCTION6 General6.1 The low voltage interconnecting system shall be formed and assembled so that it has the strengthand rigidity required to resist the abuses to whic
27、h it is subjected, without resulting in a risk of fire, electricshock, or injury to persons.7 Assembly and Mounting7.1 Provision shall be made for mounting the low voltage system to the surface types specified in theinstallation instructions. When mounting includes mechanical securement means, such
28、means shallprovide for securing the system in accordance with the installation and operation instructions. Refer to theINSTRUCTIONS, General, Section 30.7.2 The low voltage interconnecting system shall be provided with a means to mechanically secureindividual sections to each other if it is intended
29、 that interconnecting system sections be interconnected todistribute low voltage power.7.3 A low voltage interconnecting system designed to be secured to the mounting surface by fastenersadjacent to any electrical conductor or connector shall not result in damage to the conductors orconnectors. Tria
30、l installation in accordance with the installation instructions shall be used to determinecompliance with this requirement.7.4 Mounting hardware such as screws or bolts shall either be packaged with the system; or theinstallation instructions shall specify the types of acceptable mounting fasteners
31、and systems to be used.Refer to 30.3(c).7.5 Adhesive may be used to secure a low voltage system or component when the adhesive complieswith the Specialized Applications General Adhesives, Functional Analysis, and Program of Investigationfor Adhesives in the Standard for Polymeric Materials Use in El
32、ectrical Equipment Evaluations, UL746C. The maximum force for the Program of Investigation End-Product Evaluation of UL 746C shall bethe weight of the low voltage system or component part involved.OCTOBER 8, 2013 UL 2851 7UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION
33、 WITHOUT PERMISSION FROM UL8 Metal Components8.1 The low voltage system shall have a smooth finish free from defects such as projections, sharpedges, burrs or fins likely to damage conductors or connectors when installed as intended, or thatconstitute a risk of injury to persons during normal mainte
34、nance and use.8.2 Iron and steel parts shall be protected against corrosion by enameling, galvanizing, plating, powdercoating or other equivalent means, when corrosion of such parts results in a risk of fire, electric shock, orinjury to persons.Exception: This requirement does not apply to minor par
35、ts of iron or steel, such as washers, screws, orsimilar parts, edges, punched holes, and spot welds in prefinished steel.8.3 Copper, aluminum, and alloys of copper and aluminum, stainless steel, and similar materials havinginherent resistance to atmospheric corrosion may be used without additional c
36、orrosion protection.9 Polymeric Enclosure9.1 A polymeric enclosure of a system component shall comply with the requirements applicable to otherthan portable equipment specified in the Standard for Polymeric Materials Use in Electrical EquipmentEvaluations, UL 746C, when all the following conditions
37、are met:a) The instructions indicate the component may be fastened in place; andb) When fastened in place in accordance with the instructions, a tool is likely needed forremoval of the component from the work surface.9.2 A polymeric enclosure of a system component shall comply with the non-attended,
38、 non-intermittentduty portable equipment requirements of the Standard for Polymeric Materials Use in ElectricalEquipment Evaluations, UL 746C, when all the following conditions are met:a) The component is not intended for fastening in place; andb) The component, when installed in accordance with the
39、 instructions, can be readily removedfrom the work surface without the use of a tool.OCTOBER 8, 2013UL 28518UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM UL10 Adhesives10.1 Parts of a low voltage system and its low voltage equipment secured by
40、 adhesives and relied uponfor structural integrity or securement of a component within the system shall be subjected to thespecialized applications adhesives requirements in the Standard for Polymeric Material Use in ElectricalEquipment Evaluations, UL 746C.ELECTRICAL CONSTRUCTION11 General11.1 A lo
41、w voltage interconnecting system shall be provided with no more than one power feedconnector.11.2 When provided as part of the system, convenience receptacle outlets shall comply with the Standardfor Furniture Power Distribution Units, UL 962A.12 Current-Carrying Parts12.1 The current-carrying part
42、of a system shall be of copper, a copper alloy, aluminum, or other materialinvestigated and found to meet the performance requirements of this Outline.12.2 A current-carrying part shall have mechanical strength and ampacity for the intended use.12.3 Current carrying parts of a low voltage interconne
43、cting system which are exposed or can berepositioned during use, shall be plated with silver, tin, nickel, or similar corrosion resistant material towithstand the long term effects of indoor atmospheric corrosion.12.4 Iron or steel, if protected against corrosion, may be used for screws, plates, yok
44、es, springs, or otherparts that are employed as a means of clamping the conductor, if such parts are not the primarycurrent-carrying members.13 Securement of Components13.1 An uninsulated live part, including a terminal, shall be secured to its supporting surface by a methodother than friction betwe
45、en surfaces so that it will be prevented from turning or shifting in position if suchmotion may result in reduction of spacings below the minimum acceptable values. The security of acontact assembly shall maintain continued alignment of contacts.13.2 The means for preventing the turning or shifting
46、mentioned in 13.1 is to consist of more than frictionbetween surfaces for example, a properly applied lock washer is acceptable as the means for preventinga small stem-mounted switch or other device having a single-hole mounting means from turning.13.3 A live screw head or nut on the underside of an
47、 insulating base shall be prevented from looseningand shall be acceptably insulated or spaced from the mounting surface.OCTOBER 8, 2013 UL 2851 9UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM UL14 Splices and Connections14.1 A splice shall be p
48、rovided with insulation and mechanical protection equivalent to that of theconductors involved.14.2 In determining if splice insulation consisting of fabric, thermoplastic, or other type of tubing isacceptable, consideration is to be given to such factors as its dielectric properties, heat andmoistu
49、re-resistant characteristics. Thermoplastic tape wrapped over a sharp edge is not acceptable.14.3 A soldered connection shall be made mechanically secure before being soldered.14.4 A lead is considered to be mechanically secure when one or more of the following is provided priorto soldering:a) A minimum of one full wrap is provided around a terminal;b) A lead not integral with a component on a printed-wiring board is passed through an eyeletor opening, and if hand-soldered, the lead is bent 90 degrees to the board;c) A lead integral with
