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1、FOR INTERNAL UL OR CSDS USE ONLY NOT FOR OUTSIDE DISTRIBUTION Subject 414 August 12, 2005 SUMMARY OF TOPICS The following changes in requirements are being proposed: 1. Removal of Outdated Enclosure Requirements 2. Clarifi cation of Requirements for Live Parts Mounted on the Underside of an Insulati
2、ng Base 3. Clarifi cation of Requirements for Metering Transformer Cabinets and Metering Transformer Cabinet Interiors 4. Correction of Reference to a Figure in Paragraph 13.19 5. Clarifi cation of Requirements for Overall Current Rating of a Meter Socket Assembly With More Than One Metering Positio
3、n 6. Renumbering Sections 25.11 and 25.12 to Properly Identify Short Circuit Requirements 7. Clarifi cation of Marking Requirements in Table 25.1 STP BALLOTS DUE: September 11, 2005 ALL COMMENTS DUE: September 26, 2005 For your convenience in review, proposed additions to existing requirements are s
4、hown underlined and proposed deletions are shown lined-out. 1. Removal of Outdated Enclosure Requirements RATIONALE Paragraph 4.4 of Standard UL 414 provides material thickness requirements for metal enclosures with dimensions not exceeding 41 inches in length, 18 inches in width, or 8 inches in dep
5、th. Research into the history of this requirement identifi ed that this requirement was added at the time when the Standard for Enclosures for Electrical Equipment, UL 50, was adopted as the main source of enclosure requirements for meter socket enclosures. This requirement was included in Standard
6、UL 414, as it provided a reduced thickness from the thicknesses specifi ed in Standard UL 50 (at the time, UL 50 would require a thickness of 0.122 inches for aluminum). Since that time, the thickness tables contained in Standard UL 50 have been revised to allow thickness less than those in Standard
7、 UL 414. As Standard UL 50 has been updated, what was once less stringent requirements in Standard UL 414 have become more stringent than the general enclosure requirements. Based on this understanding of the history of this requirement, UL proposes that Paragraph 4.4 be deleted from Standard UL 414
8、. Copyright Underwriters Laboratories Inc. Provided by IHS under license with ULLicensee=IHS Employees/1111111001, User=Gearhard, Marcus Not for Resale, 06/01/2007 02:49:31 MDTNo reproduction or networking permitted without license from IHS -,-,- FOR INTERNAL UL OR CSDS USE ONLY NOT FOR OUTSIDE DIST
9、RIBUTION PROPOSAL 4.4 An enclosure not exceeding 41 inches (1.04 m) in length, 18 inches (457 mm) in width, or 8 inches (203 mm) in depth may be formed of 0.067 inch (1.70 mm) steel or 0.095 inch (2.41 mm) aluminum 2. Clarifi cation of Requirements for Live Parts Mounted on the Underside of an Insul
10、ating Base RATIONALE Questions regarding the interpretation of Paragraph 5.4 of Standard UL 414 have raised a concern that the requirement has not been applied uniformly. Paragraph 5.4 provides requirements for live parts and/or fasteners involving threaded members on the underside of an insulating
11、base. This paragraph provides multiple methods by which two main construction concerns can be satisfi ed. The two concerns are to ensure these live parts are: 1) Made resistant to loosening and 2) Insulated or spaced from the mounting surface. The requirement, as presently worded, has been a part of
12、 Standard UL 414 since the publication of the fi rst edition of the standard in 1957. Variations of this requirement are common in other UL Standards covering power distribution equipment (examples include Standard UL 67, UL 98, UL 489, UL 891, UL 977, UL 1008, UL 1429 and UL 1640). Using wording in
13、 these other Standards as examples, revised wording is being proposed by UL to better clarify the intent of this requirement. PROPOSAL 5.4 A live part or fastening involving threaded members (nuts and heads of screws) on the underside of a base shall be made resistant to loosening and shall be insul
14、ated or spaced from the mounting surface. This may be accomplished by countersinking such a part not less than 1/8 inch (3.2 mm) in the clear and then covering it with at least a 1/8 inch thick waterproof, insulating, sealing compound that will not soften at a temperature 15C (27F) higher than the t
15、emperature observed at the point where it is used but not lower than 65C (149F). Alternatively, a part may be secured and insulated from the mounting surface by means of a barrier or the equivalent, or by means of spacings as described in Spacings, Section 8 A live part, rivet, screw head or nut on
16、the underside of a base designed for surface mounting shall be countersunk no less than 1/8 inch (3.2 mm) in the clear and covered to a depth of not less than 1/8 inch (3.2 mm) with a waterproof, insulating sealing compound that will not soften at a temperature of 15C (27F) higher than the temperatu
17、re observed at the point where it is used but not lower than 65C (149F) Exception:A sealing compound is not required for constructions complying with 5.4.1. 5.4.1 Live parts mentioned in 5.4, which are not covered with a sealing compound, shall comply with through air and over surface spacing requir
18、ements noted in Table 8.1. Insulating materials used to provide the necessary spacings shall comply with: a) Requirements for Bases Insulating Materials, Section 5 or b) Requirements for Insulating Barriers, Section 9.1. In addition to complying with these spacing requirements, threaded fasteners wh
19、ich are not covered with a sealing compound shall be reliably prevented from loosening by being staked or upset, by a lock washer, a spring washer, or by other means. AUGUST 12, 2005SUBJECT 414-2- Copyright Underwriters Laboratories Inc. Provided by IHS under license with ULLicensee=IHS Employees/11
20、11111001, User=Gearhard, Marcus Not for Resale, 06/01/2007 02:49:31 MDTNo reproduction or networking permitted without license from IHS -,-,- FOR INTERNAL UL OR CSDS USE ONLY NOT FOR OUTSIDE DISTRIBUTION 5.5 A lock washer may be used as a means of restricting the loosening of a screw or nut as requi
21、red in 5.4. 3. Requirements for Metering Transformer Cabinets and Metering Transformer Cabinet Interiors RATIONALE Standard UL 414 is used to evaluate Metering Transformer Cabinets and Metering Transformer Cabinet Interiors. Specifi c requirements for the construction of these devices are contained
22、in Section 40 of the Standard. Paragraph 40.1.1 of Standard UL 414 refers to UL 414, Sections 3-7, 9 and 10 for requirements. These sections do not address the higher current ratings that can be applied to this equipment (6000 amperes). Requirements missing from these sections are sizing of wiring t
23、erminals for larger conductors (Standard UL 414 does not address wire sizes larger than 750 kcmil) and grounding and bonding requirements for devices rated over 2000 amperes. Other sections of Standard UL 414 do address larger wire sizes, as is the case with the tables for wire bending spaces, which
24、 include requirements for conductors up to 2000 kcmil. Applicable requirements are provided in the Standard for Dead-Front Switchboards, UL 891. UL proposes that requirements for conductor ampacity and sizing of bonding jumpers and grounded service conductors be copied from Standard UL 891 and inclu
25、ded in Tables 7.1 and 11.1 of Standard UL 414. It is also noted that Paragraph 40.2.1 of Standard UL 414 refers to Section 6 and Standard UL 891 for requirements. Paragraph 40.2.1 references Standard UL 891 for requirements as they relate to the connection of bus bars to bus bars or bus bars to wire
26、s. Section 6 of Standard UL 414, titled “Current-Carrying Parts,” does not provide requirements for sizing of bus bars. Standard UL 891 has been used in the past to evaluate sizing of bus bars used in transformer cabinets. UL proposes that a reference to Standard UL 891 be provided in Standard UL 41
27、4 as a new Section 40.3 to align with present practice. The addition of this new Section would result in the subsequent renumbering of existing Section 40.3. PROPOSAL Table 7.1 Ampacity of insulated conductors Size,Conduit trade size inches fora Temperature rating of conductor 75C (167F)90C (194F)b
28、AWG or kcmil (mm2)3 Wires4 WiresCopperAluminumCopperAluminum 142.11/21/21520 123.31/21/220152015 105.31/21/230253025 88.43/4150405545 613.31165507560 421.211-1/485c65c9575 326.71-1/41-1/4100c75c11085 233.61-1/41-1/4115c90c130100 142.41-1/41-1/2130c100c150115 1/053.51-1/22150c120c170135 2/067.41-1/22
29、175c135c195150 3/085.022200c155c225175 4/0107.022-1/2230c180c260205 AUGUST 12, 2005SUBJECT 414-3- Table 7.1 Continued on Next Page Copyright Underwriters Laboratories Inc. Provided by IHS under license with ULLicensee=IHS Employees/1111111001, User=Gearhard, Marcus Not for Resale, 06/01/2007 02:49:3
30、1 MDTNo reproduction or networking permitted without license from IHS -,-,- FOR INTERNAL UL OR CSDS USE ONLY NOT FOR OUTSIDE DISTRIBUTION Table 7.1 Continued Size,Conduit trade size inches fora Temperature rating of conductor 75C (167F)90C (194F)b AWG or kcmil (mm2)3 Wires4 WiresCopperAluminumCopper
31、Aluminum kcmil 2501272-1/22-1/2255c205c290230 3001522-1/23285c230c320255 3501772-1/23310c250c350280 40020333335c270c380305 50025333-1/2380c310c430350 60030433-1/2420c340c475385 7003553-1/24460375520420 7503803-1/24475385535435 8004053-1/24490395555450 9004563-1/24520425585480 100050645545445615500 1
32、25063355590485665545 150076056625520705585 175088756650545735615 2000101356665560750630 NOTES 1 For a multiple-conductor connector at a terminal, the value is to be multiplied by the number of 1/0 AWG and larger conductors that the terminal will accommodate. 2 These values of ampacity apply only if
33、no more than three conductors will be fi eld-installed in the conduit. If four or more conductors, other than a neutral that carries the unbalanced current, will be installed in a conduit (as may occur because of the number of conduit hubs provided or because of the number of wires necessary in cert
34、ain polyphase systems or for other reason), the ampacity of each of those conductors is reduced as shown in Table 7.2. a Conduit size based on use of conductors having insulation thickness comparable to that of Type THW conductors and with conduit hubs or knockouts provided in the enclosure. b A met
35、er socket may be rated for use with conductors on the line side having 90C (194F) ampacity under the following conditions: 1) Tested in accordance with Exception No. 3 to 13.6, with temperature rise limits as specifi ed in 13.3. 2) Marked in accordance with 25.10.5. c With respect to Exception No. 4
36、 to 13.6, equipment intended for use in a three-wire, single-phase dwelling service circuit with 75C (167F) rated conductors and marked in accordance with 25.3.5 may be investigated for ratings in accordance with the conductor ampacities specifi ed in Table 7.3. AUGUST 12, 2005SUBJECT 414-4- Copyrig
37、ht Underwriters Laboratories Inc. Provided by IHS under license with ULLicensee=IHS Employees/1111111001, User=Gearhard, Marcus Not for Resale, 06/01/2007 02:49:31 MDTNo reproduction or networking permitted without license from IHS -,-,- FOR INTERNAL UL OR CSDS USE ONLY NOT FOR OUTSIDE DISTRIBUTION
38、Table 11.1 Size of bonding jumper and grounded service conductor Ampere rating not exceeding Size of main bonding jumper (minimum)a,b,c Cross section of main bonding jumper in square inches (minimum)a,b,c Grounded service conductor (minimum) CopperAluminumCopperAluminumCopperAluminum 908 AWG6 AWG0.0
39、13d0.021d8 AWG6 AWG 100640.021d0.033d64 125640.021d0.033d64 150640.021e0.033e64 200420.033e0.052e42 30021/00.052f,g0.083f,g21/0 4001/0h3/0h0.083g,h0.132g,h1/03/0h 5000 1/03/00.0830.1321/03/0 6002/04/00.1050.1662/04/0 8002/04/00.1050.1662/04/0 10003/0250 kcmil0.1320.1963/0250 kcmil 1200250 kcmil2500.
40、1960.196250 kcmil250 16003004000.2360.314300400 20004005000.3140.393400500 25005007000.3930.550500700 30006007500.4710.589600750 400075010000.5890.7857501000 500090012500.7130.9819001250 6000125015000.9811.17812501500 a The cross section may be reduced to 12.5 percent of the total cross section of t
41、he largest main service conductor(s) of the same material (copper or aluminum) for any phase on equipment rated 1200 amperes and above. b For equipment rated 1200 amperes or more and that has wiring terminals intended to connect service conductor wires sized larger than 600 kcmil copper or 750 kcmil
42、 aluminum, the cross section of the main bonding jumper shall be at least 12.5 percent of the total cross section of the largest main service conductor(s) of the same material (copper or aluminum) for any phase. c See Table 11.2 for SI equivalents. d A No. 8 (4.2 mm diameter) or larger brass or No.
43、10 (4.8 mm diameter) or larger steel screw may be used. e A No. 10 or larger brass or steel screw may be used. f A No. 10 or larger brass screw may be used. g A 1/4 inch (6.4 mm) diameter or larger brass or steel screw may be used. h When the ampere rating is 400 and the wire terminal connectors for
44、 the main service conductors are rated for two 3/0 AWG copper or two No. 250 kcmil aluminum conductor, but will not accept a 600 kcmil conductor, these values may be reduced to 2 AWG (0.052 square-inch) copper or 0 AWG (0.083 square-inch) aluminum. 40.2.1 In addition to the requirements specifi ed i
45、n Current-Carrying Parts, Section 6, the requirements for The connection of bus bars to bus bars or bus bars to wires shall comply with the applicable requirements for current-carrying parts as specifi ed in the Standard for Dead-Front Switchboards, UL 891. 40.3 Spacings Sizing of bus bars 40.3.1 Th
46、e spacings for a metering transformer cabinet or metering transformer cabinet interior of the bus type shall be as indicated in Table 40.1. In addition to the requirements specifi ed in Current-Carrying Parts, Section 6, bus bars shall comply with the applicable requirements for current-carrying par
47、ts as specifi ed in the Standard for Dead-Front Switchboards, UL 891. AUGUST 12, 2005SUBJECT 414-5- Copyright Underwriters Laboratories Inc. Provided by IHS under license with ULLicensee=IHS Employees/1111111001, User=Gearhard, Marcus Not for Resale, 06/01/2007 02:49:31 MDTNo reproduction or network
48、ing permitted without license from IHS -,-,- FOR INTERNAL UL OR CSDS USE ONLY NOT FOR OUTSIDE DISTRIBUTION 40.4 Spacings 40.4.1 The spacings for a metering transformer cabinet or metering transformer cabinet interior of the bus type shall be as indicated in Table 40.1. 4. Correction of Reference to
49、a Figure in Paragraph 13.19 RATIONALE Paragraph 13.19 of Standard UL 414 details requirements for testing meter socket assemblies intended for more than one meter. The last sentence of this paragraph incorrectly references Figure 13.3, titled “Dimensions for jumper bars of Class 320 simulated meter,” rather than Figure 13.4 titled “Jumper for