1、UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL UL 797A Electrical Metallic Tubing Aluminum and Stainless Steel STANDARD FOR SAFETYUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM ULUL C
2、OPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL UL Standard for Safety for Electrical Metallic Tubing Aluminum and Stainless Steel, UL 797A Third Edition, Dated January 30, 2014 Summary of Topics This revision was issued to incorporate the follo
3、wing changes: 1. Removal of the term mandrel The revised requirements are substantially in accordance with Proposal(s) on this subject dated December 2, 2016. Text that has been changed in any manner or impacted by ULs electronic publishing system is marked with a vertical line in the margin. All ri
4、ghts reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form by any means, electronic, mechanical photocopying, recording, or otherwise without prior permission of UL. UL provides this Standard as is without warranty of any kind, either expre
5、ssed or implied, including but not limited to, the implied warranties of merchantability or tness for any purpose. In no event will UL be liable for any special, incidental, consequential, indirect or similar damages, including loss of prots, lost savings, loss of data, or any other damages arising
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7、ectronic versions of ULs Standards for Safety agree to defend, indemnify, and hold UL harmless from and against any loss, expense, liability, damage, claim, or judgment (including reasonable attorneys fees) resulting from any error or deviation introduced while purchaser is storing an electronic Sta
8、ndard on the purchasers computer system. JANUARY 20, 2017 UL 797A tr1UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL JANUARY 20, 2017 UL 797A tr2 No Text on This PageUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBU
9、TION WITHOUT PERMISSION FROM UL JANUARY 30, 2014 (Title Page Reprinted: January 20, 2017) 1 UL 797A Standard for Electrical Metallic Tubing Aluminum and Stainless Steel Prior to the third edition, the previous editions covered requirements for aluminum electrical metallic tubing and were entitled St
10、andard for Electrical Metallic Tubing Aluminum. First Edition July, 2000 Second Edition July, 2007 Third Edition January 30, 2014 This ANSI/UL Standard for Safety consists of the Third Edition including revisions through January 20, 2017. The most recent designation of ANSI/UL 797A as an American Na
11、tional Standard (ANSI) occurred on January 20, 2017. ANSI approval for a standard does not include the Cover Page, Transmittal Pages, and Title Page. Comments or proposals for revisions on any part of the Standard may be submitted to UL at any time. Proposals should be submitted via a Proposal Reque
12、st in ULs On-Line Collaborative Standards Development System (CSDS) at https:/. ULs Standards for Safety are copyrighted by UL. Neither a printed nor electronic copy of a Standard should be altered in any way. All of ULs Standards and all copyrights, ownerships, and rights regarding those Standards
13、shall remain the sole and exclusive property of UL. COPYRIGHT 2017 UNDERWRITERS LABORATORIES INC. ANSI/UL 797A-2017UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL JANUARY 30, 2014 ELECTRICAL METALLIC TUBING ALUMINUM AND STAINLESS STEEL - UL
14、797A 2 No Text on This PageUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL CONTENTS INTRODUCTION 1 Scope .4 2 Units of Measurement .4 3 References 4 GENERAL 4 Tube 4 5 Protective Coatings .5 6 Straight Tubing .5 7 Elbows 7 8 Examination of t
15、he Finished Product by the Manufacturer .8 PERFORMANCE 9 Bending 9 MARKINGS 10 General .9 JANUARY 30, 2014 ELECTRICAL METALLIC TUBING ALUMINUM AND STAINLESS STEEL - UL 797A 3UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL INTRODUCTION 1 Scop
16、e 1.1 These requirements cover aluminum and stainless steel electrical metallic tubing (EMT) and elbows in trade sizes 3/8 4 (12 103) for use as a metal raceway for the installation of wires and cables in accordance with the National Electrical Code. The values in parentheses are metric designators
17、of tubing. 1.2 Tubing provided with an exterior coating of zinc or a zinc-based, nonmetallic, or other alternate corrosion-resistant material and an interior coating of an organic or zinc material, is covered by the Standard for Electrical Metallic Tubing Steel, UL 797. 2 Units of Measurement 2.1 Va
18、lues stated without parentheses are the requirement. Values in parentheses are explanatory or approximate information. 3 References 3.1 Any undated reference to a code or standard appearing in the requirements of this standard shall be interpreted as referring to the latest edition of that code or s
19、tandard. GENERAL 4 Tube 4.1 Each tube shall be of an aluminum alloy or stainless steel containing no more than 0.40 percent copper. Other metal shall be evaluated. 4.2 Each tube shall have a circular cross section. All seams shall be thoroughly welded. 4.3 A welded seam shall be without any metal tr
20、imming, sharp edge or sharp projection. JANUARY 30, 2014 ELECTRICAL METALLIC TUBING ALUMINUM AND STAINLESS STEEL - UL 797A 4UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL 5 Protective Coatings 5.1 Aluminum and stainless steel electrical met
21、allic tubing does not require a protective coating. Exception: Aluminum electrical metallic tubing intended for use in concrete, for direct burial, or for use in severely corrosive environments, shall be provided with a protective coating. 5.2 It is not prohibited for one or more protective coatings
22、 to be employed. When such protective coatings have not been evaluated as supplying corrosion resistance for the tube they shall be marked in accordance with 10.4. 5.3 Nonmetallic coatings shall be evaluated with respect to ame propagation, the t of couplings, and electrical continuity with coupling
23、s. 6 Straight Tubing 6.1 The length of electrical metallic tubing shall not be greater than given in Table 6.1. Table 6.1 Length Trade size (Metric designator) Maximum length, feet (meters) 1/2 3/4 16 21 10 1/4 3.05 12 2 75 3 1 5 1 / 4 4.58 2-1/2 4 63 103 20 1/4 6.10 6.2 The external diameter and we
24、ight of nished tubing shall be within the limits indicated in Table 6.2 or 6.3. Table 6.2 Dimensions and weight in USA customary units Trade size (Metric designator) External diameter in inches Internal diameter in inches (not a requirement) Wall thickness in inches (not a requirement) Aluminum mini
25、mum weight in pounds per foot of length a Stainless steel minimum weight in pounds per foot of length d 1/2 16 0.706 0.005 0.622 0.042 0.099 0.300 3/4 21 0.922 0.005 0.824 0.049 0.151 0.500 1 27 1.163 0.005 1.049 0.057 0.221 0.680 1-1/4 35 1.510 0.005 1.380 0.065 0.329 1.000 1-1/2 41 1.740 0.005 1.6
26、10 0.065 0.381 1.100 2 53 2.197 0.005 2.067 0.065 0.484 1.380 2-1/2 4 63 103 b b b c c a The minimum weight of 1/2 2 trade sizes of nonferrous tubing is to be determined by multiplying the weight shown for aluminum tubing by the ratio of A to B: where A is the density (in pounds per cubic inch) of t
27、he nonferrous alloy used; and B is 0.098, which is the density of aluminum in pounds per cubic inch. b The dimensions of the 2-1/2, 3, 3-1/2, and 4 trade sizes of tubing are to be established by an investigation that takes into account the characteristics of the particular alloy used. c The minimum
28、weight of the 2-1/2, 3, 2-1/2, and 4 trade sizes of tubing is to be established by investigation of the effect that the dimensions and the particular alloy used have on the strength and rigidity of the nished tubing. JANUARY 30, 2014 ELECTRICAL METALLIC TUBING ALUMINUM AND STAINLESS STEEL - UL 797A
29、5 Table 6.2 Continued on Next PageUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL Table 6.2 Continued Trade size (Metric designator) External diameter in inches Internal diameter in inches (not a requirement) Wall thickness in inches (not a
30、requirement) Aluminum minimum weight in pounds per foot of length a Stainless steel minimum weight in pounds per foot of length d d The weight shown is for a stainless steel alloy (Type 304 or 316) with a density of 0.284 pound mass per cubic inch. For a stainless steel alloy of a different density,
31、 the minimum weight shall be determined by multiplying the weight shown by the ratio of the density of the alloy used in pound mass per cubic inch to 0.284. Table 6.3 Dimensions and weight in metric units Trade size (Metric designator) External diameter in mm Internal diameter in mm (not a requireme
32、nt) Wall thickness in mm (not a requirement) Aluminum minimum weight in kilograms per meter of length a Stainless steel, minimum weight in kilograms per meter of length d 1/2 16 17.93 0.13 15.80 1.07 0.197 0.136 3/4 21 23.42 0.13 20.93 1.24 0.224 0.226 1 27 29.54 0.13 26.64 1.45 0.329 0.308 1-1/4 35
33、 38.35 0.13 35.05 1.65 0.489 0.453 1-1/2 41 44.20 0.13 40.89 1.65 0.566 0.498 2 53 55.80 0.13 52.50 1.65 0.721 0.625 2-1/2 4 63 103 b b b c c a The minimum weight of 1/2 2 trade sizes of nonferrous tubing is to be determined by multiplying the weight shown for aluminum tubing by the ratio of A to B:
34、 where A is the density (in kilograms per cubic meter) of the nonferrous alloy used; and B is 2710, which is the density of aluminum in kilograms per cubic meter. b The dimensions of the 2-1/2, 3, 3-1/2, and 4 trade sizes of tubing are to be established by an investigation that takes into account th
35、e characteristics of the particular alloy used. c The minimum weight of the 2-1/2, 3, 2-1/2, and 4 trade sizes of tubing is to be established by investigation of the effect that the dimensions and the particular alloy used have on the strength and rigidity of the nished tubing. d The weight shown is
36、 for a stainless steel alloy (Type 304 or 316) with a density of 7861 kg/m 3 . For a stainless steel alloy of a different density, the minimum weight shall be determined by multiplying the weight shown by the ratio of the density of the a l l o yu s e di nk g / m 3 to 7861. 6.3 Each length of tubing
37、 on which measurements are made is to be nished, 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 nished tub
38、ing are to be determined for comparison with the limits specied 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 machinists micrometer caliper that has a at-ended spindle, a at anvil, and is calibrated having a minimum resolution of 0.001
39、 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. JANUARY 30, 2014 ELECTRICAL METALLIC TUBING ALUMINUM AND STAINLESS STEEL - UL 797A 6UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FR
40、OM UL 6.5 If desired, methods, tools, and measurement techniques may be employed to determine compliance with the above dimensional requirements provided they are accurate to within 0.001 inch or 0.01 mm and have been determined to be acceptable. 6.6 To determine the outside diameter when using a mi
41、crometer 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
42、size of tubing involved. The recorded diameters shall not differ from the diameter in the applicable table by more than the specied 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. accordi
43、ng 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 d
44、egrees. The radius R and the length L S of the straight portions at the ends of an elbow shall not be smaller than indicated in Table 7.1. See Figure 7.1. Table 7.1 Minimum dimensions of elbows Radius R to center line of tube, Shortest length L s of each straight end portion of tubing, Trade size (M
45、etric designator) inches (mm) inches (mm) 1/2 16 4 102 1-1/2 38 3/4 21 4-1/2 114 1-1/2 38 1 27 5-3/4 146 1-7/8 48 1-1/4 35 7-1/4 184 2 51 1-1/2 41 8-1/4 210 2 51 2 53 9-1/2 241 2 51 2 - 1 / 2 46 3 1 0 3aaaa a The dimensions of the 2-1/2, 3, 3-1/2, and 4 trade sizes of nonferrous tubing are to be est
46、ablished by an investigation that takes into account the characteristics of the particular alloy used. This is generated text for gtxt. JANUARY 30, 2014 ELECTRICAL METALLIC TUBING ALUMINUM AND STAINLESS STEEL - UL 797A 7UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION
47、WITHOUT PERMISSION FROM UL 8 Examination of the Finished Product by the Manufacturer 8.1 Each length of tubing shall be examined visually on both interior and exterior surfaces. There shall not be any burrs or ns, or other defects on interior surfaces. 8.2 The examination of interior surfaces of the
48、 tubing is to be made by looking through the products, rst from one end then from the other, at an articial light. 8.3 Elbows are to be examined as described in 8.1 and 8.2 as straight lengths before the lengths are bent. In addition, elbows are to be monitored during the bending operation for evide
49、nce of damage. Figure 7.1 Conduit elbows JANUARY 30, 2014 ELECTRICAL METALLIC TUBING ALUMINUM AND STAINLESS STEEL - UL 797A 8UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL PERFORMANCE 9 Bending 9.1 One specimen of the smallest available trade size of nished tubing produced by the manufacturer shall be capable of being bent into a quarter of a circle, using any suitable bending equipm
