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1、FOR INTERNAL UL OR CSDS USE ONLY NOT FOR OUTSIDE DISTRIBUTION Subject 1773 June 1, 2007 SUMMARY OF TOPICS The following changes in requirements are being proposed: 1. Publication of a New Edition of Standard UL 1773 and the following revisions to the standard: a) Addition of Requirement for Location
2、 of Grounding Electrode Termination and b) Addition of Requirement that Bonding Screws are Inserted into a Part Provided with at Least Two Full Threads COMMENTS DUE: July 2, 2007 For your convenience in review, proposed additions to existing requirements are shown underlined and proposed deletions a
3、re shown lined-out. 1. Publication of a New Edition of Standard UL 1773 and the following revisions to the standard: a) Addition of Requirement for Location of Grounding Electrode Termination and b) Addition of Requirement that Bonding Screws are to be Inserted into a Part Provided with at Least Two
4、 Full Threads RATIONALE Proposal submitted by: Jake Killinger, UL The proposed Fourth Edition of the Standard for Termination Boxes, UL 1773, includes the following proposals: a) Addition of Requirement (Paragraph 12.3) for Location of Grounding Electrode Termination Requirements contained in Sectio
5、n 250.24(A)(4) of the 2005 National Electrical Code addresses the common allowance of terminating the grounding electrode conductor to the equipment grounding terminal bar (rather than the grounded conductor terminal (neutral) when a main bonding jumper is installed. Similar to other standards, UL p
6、roposes to include this allowance by fi rst adding the requirement for termination to the grounded conductor terminal and secondly, adding an exception to this requirement. Similar approaches have been used on other UL standards, i.e. UL 67. b) Addition of Requirement (Paragraph 12.4) that Bonding S
7、crews are to be Inserted into a Part Provided with at Least Two Full Threads It is the intent that all electrical connections, including those for grounding and bonding, be reliable and electrically conductive. Requirements detailed in Section 250.8 of the 2005 National Electrical Code addressed thi
8、s concern by disallowing sheet metal screws to be used to connect grounding conductors or connection devices to enclosures. Allowances for the use of bonding screws are contained in Exception number 1 of Paragraph 12.1, with additional reference to the footnotes in Table 12.1. In other standards, UL
9、 addressed the disallowance of sheet metal screws by introducing the two full thread requirement. Sheet metal screws do not meet this requirement. UL proposes to include similar requirements to ensure the same level of reliability. Copyright Underwriters Laboratories Inc. Provided by IHS under licen
10、se with ULLicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 06/18/2007 22:30:42 MDTNo reproduction or networking permitted without license from IHS -,-,- FOR INTERNAL UL OR CSDS USE ONLY NOT FOR OUTSIDE DISTRIBUTION PROPOSAL JUNE 1, 2007SUBJECT 1773-2- Copyright Underwriters Labor
11、atories Inc. Provided by IHS under license with ULLicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 06/18/2007 22:30:42 MDTNo reproduction or networking permitted without license from IHS -,-,- FOR INTERNAL UL OR CSDS USE ONLY NOT FOR OUTSIDE DISTRIBUTION INTRODUCTION 1 Scope 1.1
12、These requirements cover termination boxes rated 600 V or less that consist of lengths of bus bars, terminal strips, or terminal blocks with provision for wire connectors to accommodate incoming or outgoing conductors or both and are intended to be used in accordance with the National Electrical Cod
13、e, NFPA 70. Termination boxes are investigated for use on the line or load side of service equipment. 1.2 The incoming and outgoing conductors may be routed through knockouts or openings in the box for cable, conduit, or electrical metallic tubing. The termination box may also have special openings
14、to match with similar openings in other equipment such as meter sockets, panelboards, switch or circuit breaker enclosures, wireways, and the like. 1.3 These requirements also cover termination bases to be fi eld installed in termination boxes and termination boxes in which termination bases are to
15、be fi eld installed. 1.4 These requirements do not cover equipment connected only by bus bars for both input and output circuits, nor equipment containing switching devices, relays, or overcurrent protective devices. These requirements also do not cover busway fi ttings known as End Cable Tap Boxes
16、which are covered by the Standard for Busways, UL 857. 2 General 2.1 Components 2.1.1 Except as indicated in 2.1.2, a component of a product covered by this standard shall comply with the requirements for that component. See Appendix A for a list of standards covering components generally used in th
17、e products covered by this standard. 2.1.2 A component is not required to comply with a specifi c requirement that: a) Involves a feature or characteristic not required in the application of the component in the product covered by this standard, or b) Is superseded by a requirement in this standard.
18、 2.1.3 A component shall be used in accordance with its rating established for the intended conditions of use. 2.1.4 Specifi c components are incomplete in construction features or restricted in performance capabilities. Such components are intended for use only under limited conditions, such as cer
19、tain temperatures not exceeding specifi ed limits, and shall be used only under those specifi c conditions. JUNE 1, 2007SUBJECT 1773-3- Copyright Underwriters Laboratories Inc. Provided by IHS under license with ULLicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 06/18/2007 22:30:
20、42 MDTNo reproduction or networking permitted without license from IHS -,-,- FOR INTERNAL UL OR CSDS USE ONLY NOT FOR OUTSIDE DISTRIBUTION 2.2 Units of measurement 2.2.1 Values stated without parentheses are the requirement. Values in parentheses are explanatory or approximate information. 2.3 Undat
21、ed references 2.3.1 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 standard. 3 Glossary 3.1 For the purpose of this standard, the following defi nition applies. 3.2 TERMINATION BASE An
22、 assembly mounted as a common structure constituting all the elements of a termination box except for the enclosure and intended for use in one or more specifi c termination boxes. CONSTRUCTION 4 Enclosure 4.1 General 4.1.1 Unless specifi ed otherwise in this standard, a termination box enclosure sh
23、all comply with the Standard for Enclosures for Electrical Equipment, UL 50. Exception No. 1: A termination box enclosure may be constructed with a special opening for connection to other equipment if the termination box is marked as specifi ed in 23.5.1 and the construction complies with 4.1.2. Exc
24、eption No. 2: A termination box intended for fl oor mounting or of a post or pedestal type may have an open bottom. 4.1.2 A termination box provided with special openings shall be provided with: a) Mating surfaces of at least 3/8 inch (9.5 mm) on each side of the opening as shown in Figure 4.1. b) M
25、eans to close the end of an enclosure with an available fi tting marked for use with the termination box. This is generated text for fi gtxt. JUNE 1, 2007SUBJECT 1773-4- Copyright Underwriters Laboratories Inc. Provided by IHS under license with ULLicensee=IHS Employees/1111111001, User=Wing, Bernie
26、 Not for Resale, 06/18/2007 22:30:42 MDTNo reproduction or networking permitted without license from IHS -,-,- FOR INTERNAL UL OR CSDS USE ONLY NOT FOR OUTSIDE DISTRIBUTION 4.2 Conduit connections 4.2.1 A nonmetallic enclosure shall have a bonding means provided to maintain continuity of grounding b
27、etween all conduit openings. For a construction having a threaded opening or nipple for metal conduit, the bonding means shall be assembled to the enclosure. For a construction having a non-threaded opening, the bonding means may be provided as separate parts for fi eld installation. An enclosure in
28、tended for fi eld assembly of the bonding means shall be provided with instructions for installation. The instructions shall include the identifi cation of the parts and their method of installation. Exception:The bonding means need not be provided in a nonmetallic enclosure not intended for use wit
29、h a metallic conduit system if the enclosure is marked as specifi ed in 23.8.1. 4.2.2 A nonmetallic enclosure having provision for connection of rigid metallic conduit or rigid nonmetallic conduit shall be investigated for such use as specifi ed in the Conduit Connection Tests, Section 20. Figure 4.
30、1 Overlap at special opening JUNE 1, 2007SUBJECT 1773-5- Copyright Underwriters Laboratories Inc. Provided by IHS under license with ULLicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 06/18/2007 22:30:42 MDTNo reproduction or networking permitted without license from IHS -,-,- FO
31、R INTERNAL UL OR CSDS USE ONLY NOT FOR OUTSIDE DISTRIBUTION 4.3 Provision for support 4.3.1 Provision for support or other mounting means for a nonmetallic termination box shall be outside the termination box, unless the termination box is constructed such that the conductors within the box cannot c
32、ontact the supporting screws. 4.3.2 So that contact between a supporting screw and conductors within a box will be prevented as required in 4.3.1, a hole in a box for a screw shall be located in a recess constructed such that there will be a spacing of not less than 1/32 inch (0.8 mm) between the pl
33、ane of the top of the recess and the head of the largest screw that is provided with the box. If a screw is not provided with a box, this spacing shall be measured using the largest: a) Round-head screw, specifi ed in Table 4.1, that can be inserted in a hole that is not chamfered or b) Flat-head sc
34、rew that can be inserted in a hole that is chamfered. Table 4.1 Supporting-screw hole dimensions Nominal screw size Diameter of hole,Minimum dimensions of recess Diameter,Depth, inch(mm)inch(mm)inch(mm) 60.1383.511/46.44/323.2 80.1644.1719/647.59/643.6 100.1904.8311/328.75/324.0 120.2165.4925/649.91
35、1/644.4 1/40.2506.3529/6411.513/645.2 5/160.3137.959/1614.315/646.0 5 Mounting Post or Pedestal 5.1 General 5.1.1 A mounting post or pedestal shall not be less than 12 square inches (77 cm2) in cross-sectional area and 2-1/2 inches (63.5 mm) deep, and at least three sides shall be fabricated of galv
36、anized steel not less than 0.070 inch (1.8 mm) thick. Exception:A mounting post or pedestal that complies with the Torque Deformation Test, Section 17, and the Beam Loading Defl ection Test, Section 18, need not be 12 square inches in cross-sectional area or less than 2-1/2 inches deep, and may be f
37、abricated of galvanized steel not less than 0.056 inch (1.42 mm) thick. 5.1.2 That portion of a post located below grade level and up to 12 inches (305 mm) above grade level shall be painted on both the inside and outside surfaces in addition to being galvanized. JUNE 1, 2007SUBJECT 1773-6- Copyrigh
38、t Underwriters Laboratories Inc. Provided by IHS under license with ULLicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 06/18/2007 22:30:42 MDTNo reproduction or networking permitted without license from IHS -,-,- FOR INTERNAL UL OR CSDS USE ONLY NOT FOR OUTSIDE DISTRIBUTION 5.2 C
39、over 5.2.1 A cover or cap for a mounting post or pedestal shall be of metal not thinner than as required in 5.1.1, or nonmetallic material complying with the Standard for Enclosures for Electrical Equipment, UL 50. A cover or cap fabricated from 0.056 inch (1.4 mm) thick steel may be any length prov
40、ided its width does not exceed 10 inches (254 mm). Exception:A cover or cap provided on a mounting post or pedestal to close unused openings intended to accommodate a fi eld-installed unit may be thinner than 0.056 inch if the cover or cap complies with the defl ection test described in the Conduit
41、Connection Tests, Section 20. 5.3 Grade level 5.3.1 The distance between the marked fi nal grade level of a mounting post as covered in 23.7.1 or the bottom of the base of a mounting pedestal and the lowest live part shall not be less than 12 inches (305 mm). 5.4 Wire opening 5.4.1 The opening provi
42、ded in the base of a mounting post for the entrance of underground wiring shall be rolled, fl anged, or equipped with a bushing so that there will be a smoothly rounded surface against which the cables can bear. The upper edge of the opening shall be at least 18 inches (457 mm) below the marked fi n
43、al grade level. 5.5 Instructions 5.5.1 A mounting post or pedestal shall be provided with instructions indicating the correct mounting procedure. 5.6 Mounting provision 5.6.1 A pedestal shall have mounting holes or similar provision in the base for securing the pedestal to a concrete slab. Aluminum
44、in a pedestal enclosure shall not be in contact with the concrete mounting pad. A metallic or nonmetallic coating used to separate aluminum from a concrete pad shall be tested to demonstrate resistance to corrosion not less than that of galvanized (G90 zinc coating) steel that is 0.061 inch (1.55 mm
45、) thick. 6 Ventilation Openings 6.1 If ventilation openings are provided, they shall comply with 6.2 6.10. 6.2 Ventilation openings shall be guarded so that there is no direct access to a live part as covered in 6.3 and 6.4. 6.3 Ventilation openings shall be: a) Screened or louvered openings with in
46、ternal barriers or b) Hoods or stacks with labyrinth air passages. JUNE 1, 2007SUBJECT 1773-7- Copyright Underwriters Laboratories Inc. Provided by IHS under license with ULLicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 06/18/2007 22:30:42 MDTNo reproduction or networking permi
47、tted without license from IHS -,-,- FOR INTERNAL UL OR CSDS USE ONLY NOT FOR OUTSIDE DISTRIBUTION 6.4 A barrier shall be of such dimensions and located so that a straight line drawn from any live part past the edge of the barrier will intersect the enclosure minimum 1/4 inch (6.4 mm) from the edge o
48、f an opening. 6.5 A ventilation opening slot, louver, or the like shall be protected by one or more baffles, barriers, or other obstructions of such dimensions and locations that any access path to a live part requires at least two changes of direction, one of which involves an angle of 90 degrees or more from a straight line, as shown in Figure 6.1. In addition, if the minor dimension of a ventilation opening is larger than 1/4 inch (6.4 mm), it shall be protected by a screen having a minor dimension not larger than 1/4 inch. This is generated text for f