UL 870:1999 pdf download Wireways, Auxiliary Gutters, and Associated Fittings
1 Scope
1.1 These requirements cover wireways, auxiliary gutters, and associated fittings to be employed inaccordance with the National Electrical Code,NFPA 70.
1.2 These requirements do not cover rigid or flexible conduit, surface raceways, underfloor raceways, norother products of a similar nature that are covered by individual requirements.
1.3 A product that contains features, characteristics, components, materials, or systems new or diferentfrom those covered by the requirements in this Standard, and that involves a risk of fire, electric shock. orinjury to persons shall be evaluated using the appropriate additional component and end-productrequirements to determine that the level of safety as originally anticipated by the intent of this Standard ismaintained. A product whose features, characteristics, components, materials, or systems conflict withspecific requirements or provisions of this Standard shall not be judged to comply with this Standard.Where appropriate,revision of requirements shall be proposed and adopted in conformance with themethods employed for development, revision, and implementation of this Standard.
1.3 revised August 20.1999
2 Glossary
2.1 For the purpose of this standard the following definitions apply.
2.2 ASSOCIATED FITTING – A part that is used in the assembly of a complete wireway system, suchas an elbow, tee, cross, end closer, or hanger.
2.3 AUXILIARY GUTTER – A section of wireway used to supplement the wiring space at a distributioncenter, switchboard, or similar location in a wiring system.
2.4 WIREWAY – A sheet-metal trough with a hinged or removable cover for housing and protectingelectric wires and cables and in which conductors are laid in place after the wireway system has beeninstalled as a complete system.
2.4 revised August 20.1999
3 Units of Measurement
3.1 lf a value for measurement is followed by a value in other units in parentheses, the first stated valueis the requirement. The second value may be only approximate.
4 General
4.1 Wireways, auxiliary gutters, and associated fitings shall employ materials that are acceptable for theparticular use. and shall be made and finished with the degree of uniformity and grade of workmanship
practicable in a well-equipped factory.
4.2 A wireway system shall include all wireways and fittings required to make a complete installation inaccordance with the National Electrical Code,ANSNFPA 70-1999.
4.2 revised August 20,1999
4.3 Unless otherwise noted, auxiliary gutters and fitings shall comply with all of the requirements forwireways.
5 Design
5.1 A wireway shall be constructed, such that the interconnection of sections and fittings will provide arigid mechanical assembly and provide electrical conductivity complying with the requirements for theElectrical Continuity Test, Section 17.
5.2 A wireway shall be formed and assembled so that it will have the strength and rigidity necessary toresist the abuses to which it is likely to be subjected, without resulting in a risk of fire, electric shock, orinjury to persons due to total or partial collapse with resulting damage to conductors, loosening ordisplacement of parts, or other serious defects.
5.3 The interior of the wireway shall be free from burrs and sharp corners or edges that may abrade theinsulation on conductors or otherwise damage wiring. Screws and bolts, however used, shall not projectinto the wireway unless sharp ends and threaded sections are covered or otherwise prevented fromcoming in contact with wires.
Exception:A threaded section of a screw or bolt not having a sharp point need not be prevented fromcoming in contact with wires provided the screw or bolt does not project more than 1/32 inch (0.8 mm)into the wireway.
5.4 A flatwise elbow or tee or a similar fitting for a wireway having a rectangular cross section shall be ofthe sweep type; that is, such a fitting for a right-angle bend shall have the intermal corner replaced by adiagonal wall – see Figure 5.1 – to permit a larger bending radius for installed conductors. Sweep fittingsmay also be used in wireways of square cross section.
5.5 In a flatwise sweep fitting for a wireway of rectangular cross section, dimension A plus dimension C(the length of leg cut off by the diagonal wall) shall be equal to or exceed dimension B. See Figure 5.1.
UL 870:1999 pdf download
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