UL 870-2016 pdf download

UL 870-2016 pdf download.Wireways，Auxiliary Gutters, and Associated Fittings.
20.2 Gaskets
20.2.1 After exposure to a temperature of 156-158°F(69 -70C) in an air-circulating oven for 168 h, agasket of rubber or rubberlike material provided with a raintight wireway shall have a tensile strength notless than 75% and an elongation not less than 60% of the corresponding values of unaged samples.21 Metallic Coating Thickness Test – Metal Wireways,Auxiliary Gutters, and Associated Fittings21.1 The method of determining the thickness of a zinc or cadmium coating by the metallic coatingthickness test is described in 21.2 -21.9.The aforementioned applies only if the required thickness isspecified.
21.2 The solution to be used for the test is to be made from ditilled water and is to contain 200 g/L ofreagent grade chromic acid (CrOg) and 50 gL of reagent grade concentrated sulfuric acid (H SO,).Thelatter is equivalent to 27 mLL of reagent grade concentrated sulfuric acid, specific gravity 1.84, containing96% of H sO4.
21.3 The test solution is to be contained in a glass vessel such as a separatory funnel with the outletequipped with a stopcock and a capillary tube of approximately 0.025 in (0.64 mm) inside bore and 5.5-in(140-mm) long. The lower end of the capillary tube is to be tapered to form a tip, the drops from which areabout 0.05 mL each. To preserve an effectively constant level, a small glass tube is inserted in the top ofthe funnel through a rubber stopper and its position is to be adjusted so that when the stopcock is open,the rate of dropping is 100 15 drops per minute. If desired, an additional stopcock may be used in placeof the glass tube to control the rate of dropping.
21.4 The sample and the test solution are to be kept in the test room long enough to acquire thetemperature of the room, which is to be noted and recorded.The test is to be conducted at a roomtemperature of 70- 90°F(21 – 32C).
21.5 Each sample is to be thoroughly cleaned before testing.All grease，lacquer，paint,and othernonmetallic coatings are to be removed completely by means of suitable solvents.Samples are then tobe thoroughly rinsed in water and dried with ciean cheesecloth.Care should be exercised to avoid contactof the cleaned surface with the hands or any foreign material.
21.6 The sample to be tested is to be supported from 0.7- 1 in (17.8-25.4 mm) below the orifice, sothat the drops of solution strike the point to be tested and run off quickly.The surface to be tested shouldbe inclined about 45 degrees from horizontall.
21.7 After cleaning, the sample to be tested is to be put in place under the orifice. The stopcock is to beopened and the time in seconds is to be measured with a stop watch until the dropping solution dissolvesthe protective metal coating, exposing the base metal. The end point is the first appearance of the basemetal recognizable by the change in color at that point.
21.8 Each sample of a test lot is to be subjected to the test at three or more points， excluding cut,stenciled, and threaded surfaces, on the inside surface and at an equal number of points on the outsidesurface at places where the metal coating may be expected to be the thinnest. On enclosures made fromprecoated sheets, the external corners that are subjected to the greatest deformation are likely to havethin coatings.
lf the wireway is intended to be supported at points other than the joints, two sections of wireway sufficientlength are to be joined and supported as intended with the joint midway between the supports,and theload is to be applied at the joint.
23 Ultraviolet Light Exposure – Nonmetallic Wireways,Auxiliary Gutters, and Associated Fittings
23.1 A nonmetallic wireway,auxiliary gutter, or associated fitting that is rated “Sunlight Resistant”shallbe investigated in accordance with the applicable requirements of the Standard for Polymeric Materials -Use in Electrical Equipment Evaluations,UL 746C.
MARKING
24 General
24.1 Marking requirements identified for wireways, auxiliary gutters and associated fittings apply to bothnonmetallic and metal devices,unless specifically noted.
25 Details
25.1 Each length of wireway or auxiliary gutter and each fitting shall be plainly marked where it will bevisible after installation, with the manufacturer’s name,trademark, or other descriptive marking by whichthe organization responsible for the product may be identified – hereinafter referred to as themanufacturer’s name.
25.2 A raintight wireway shall be marked “Raintight”in such a location on the enclosure that the markingwill be conspicuous. If this marking is applied to the wireway on an individual nameplate, label, or the like,the manufacturer’s name shall be included on the nameplate or the like.