UL 797A-2017 pdf free download

UL 797A-2017 pdf free download.Electrical Metallic Tubing-Aluminum and Stainless Steel.
6.3 Each length of tubing on which measurements are made is to be finished, smooth and clean wherever it is to touch any part of a measuring device or tool. All of the individual outside diameter measurements are to be performed at the center and at least one end of the tubing.
6.4 The measurements from a length of finished tubing are to be determined for comparison with the limits specified in inches in Table 6.2. or in millimeters in Table 6.3, and are to be made by one of the following means:
a) A machinist’s micrometer caliper that has a flat-ended spindle, a flat anvil, and is calibrated having a minimum resolution of 0.001 inch or 0.01 mm: or
b) A vernier caliper that is calibrated having a minimum resolution of 0.001 inch or 0.01 mm.
6.5 Il desired, methods, tools, and measurement techniques may be employed to determine compliance with the above dimensional requirements provided they are accurate to within 1-0.001 inch or +0.01 mm and have been determined to be acceptable.
6.6 To determine the outside diameter when using a micrometer caliper or vernier caliper, at least four measurements (every 45 degrees) are necessary at each place to ensure that the largest and smallest diameters are found. The recorded diameters are to be compared with the diameter in inches in Table 6.2 or in millimeters in Table 6.3 for the trade size of tubing involved. The recorded diameters shall not differ from the diameter in the applicable table by more than the specified tolerances.
7 Elbows
7.1 Elbows shall be made from the same grade of tubing as straight lengths of electrical metallic tubing
and shall be treated. coated. etc. according to the applicable requirements for the tubing.
7.2 An elbow is not prohibited from being provided with an integral coupling which complies with the
applicable requirements in the Standard for Fittings for Cable and Conduit, UL 514B. on one or both ends.
7.3 An elbow shall not be sharper than 90 degrees. The radius R and the length Ls of the straight portions at the ends of an elbow shall not be smaller than indicated in Table 7.1. See Figure 7.1.UL 797A-2017 pdf free download.