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ANSI/NEMA C29.7-1996 (R2002, R2012)
American National Standard
Wet Process Porcelain Insulators—
High-Voltage Line-Post Type
ANSI/NEMA C29.7-1996 (R2002, R2012)
American National Standard
Wet Process Porcelain Insulators—
High-Voltage Line-Post Type
Secretariat:
National Electrical Manufacturers Association
Approved: Augus t 2012
Publis hed: May 20, 2013
American National Standards Institute, Inc.
© Copyright 2013 by National Electrical Manufacturers As s ociation
C29.7-1996 (R2002, R2012)
Page ii
NOTICE AND DISCLAIMER
The inform ation in this publication was cons idered technically s ound by the cons ens us of pers ons
engaged in the developm ent and approval of the docum ent at the tim e it was developed. C ons ens us does
not neces s arily m ean that there is unanim ous agreem ent am ong every pers on participating in the
developm ent of this docum ent.
Am erican National Standards Ins titute (ANSI) s tandards and guideline publications , of which the docum ent
contained herein is one, are developed through a voluntary cons ens us s tandards developm ent proces s .
This proces s brings together volunteers and/or s eeks out the views of pers ons who have an interes t in the
topic covered by this publication. While NEMA adm inis ters the proces s and es tablis hes rules to prom ote
fairnes s in the developm ent of cons ens us , it does not write the docum ent and it does not independently
tes t, evaluate, or verify the accuracy or com pletenes s of any inform ation or the s oundnes s of any judgm ents
contained in its s tandards and guideline publications .
NEMA dis claim s liability for any pers onal injury, property, or other dam ages of any nature whats oever,
whether s pecial, indirect, cons equential, or com pens atory, directly or indirectly res ulting from the
publication, us e of, application, or reliance on this docum ent. NEMA dis claim s and m akes no guaranty or
warranty, expres s or im plied, as to the accuracy or com pletenes s of any inform ation publis hed herein, and
dis claim s and m akes no warranty that the info rm ation in this docum ent will fulfill any of your particular
purpos es or needs . NEMA does not undertake to guarantee the perform ance of any individual
m anufacturer or s eller’s products or s ervices by virtue of this s tandard or guide.
In publis hing and m aking this docum ent available, NEMA is not undertaking to render profes s ional or other
s ervices for or on behalf of any pers on or entity, nor is NEMA undertaking to perform any duty owed by any
pers on or entity to s om eone els e. Anyone us ing this docum ent s h ould rely on his or her own independent
judgm ent or, as appropriate, s eek the advice of a com petent profes s ional in determ ining the exercis e of
reas onable care in any given circum s tances . Inform ation and other s tandards on the topic covered by this
publication m ay be available from other s ources , which the us er m ay wis h to cons ult for additional views or
inform ation not covered by this publication.
NEMA has no power, nor does it undertake to police or enforce com pliance with the contents of this docum
ent. NEMA does not certify, tes t, or ins pect products , des igns , or ins tallations for s afety or health purpos es .
Any certification or other s tatem ent of com pliance with any health or s afety–related inform ation in this
docum ent s hall not be attributable to NEMA a nd is s olely the res pons ibility of the certifier or m aker of
the s tatem ent.
© Copyright 2013 by National Electrical Manufacturers As s ociation
C29.7-1996 (R2002, R2012)
Page iii
AMERICAN
NAT IONAL
ST ANDARD
Approval of an Am erican National Standard requires verification by ANSI
that the requirem ents for due proces s , cons ens us , and other criteria for
approval have been m et by the s tandards developer.
Cons ens us is es tablis hed when, in the judgm ent of the ANSI Board of
Standards Review, s ubs tantial agreem ent has been reached by directly
and m aterially affected interes ts . Subs tantial agreem ent m eans m uch
m ore than a s im ple m ajority, but not neces s arily unanim ity. Cons ens us
requires that all views and objections be cons idered, and that a
concerted effort be m ade toward their res olution.
The us e of Am erican National Standards is com pletely voluntary; their
exis tence does not in any res pect preclude anyone, whether he has
approved the s tandards or not, from m anufacturing, m arketing,
purchas ing, or us ing products , proces s es , or procedures not conform ing
to the s tandards .
The Am erican National Standards Ins titute do es not develop s tandards
and will in no circum s tances give an interpretation of any Am erican
National Standard. Moreover, no pers on s hall have the right or authority
to is s ue an interpretation of an Am erican National Standard in the nam e
of the Am erican National Standards Ins titute. Reques ts for
interpretations s hould be addres s ed to the s ecretariat or s pons or whos e
nam e appears on the title page of this s tandard.
Caution Notice: This Am erican National Standard m ay be revis ed or
withdrawn at any tim e. The procedures of the Am erican National
Standards Ins titute require that action be taken periodically to reaffirm ,
revis e, or withdraw this s tandard. Purchas ers of Am erican National
Standards m ay receive current inform ation on all s tandards by calling or
writing the Am erican National Standards Ins titute.
Published by
National Electrical Manufacturers Association
1300 North 17th Street, Rosslyn, VA 22209 Copyright 2013 by National Electrical Manufacturers As s ociation
All rights res erved including trans lati on into other languages , res erved under the Univers al Copyright
Convention, the Berne Convention for the Protection of Literary and Artis tic Works , and the International
and Pan Am erican Copyright Conventions .
No part of thi s publ i cati on may be reproduced i n any form, i n an el ectroni c retri eval system or otherwi se, wi thout the
pri or wri tten permi ssi on of the publ i sher.
Printed in the United States of Am erica .
© Copyright 2013 by National Electrical Manufacturers As s ociation
C29.7-1996 (R2002, R2012)
Page iv
FOREWORD
(This foreword is not part of Am erican National Standard C29.7-1996 (R2002, R2012))
This s tandard is periodically reviewed for any revis ions to keep it current with advancing technology. Sugges tions for im provem ent of this s tandard will be welcom e. They s hould be s ent to National Electrical
Manufacturers As s ociation, 1300 North 17th
Street, Suite 1752, Ros s lyn, VA 22209.
This s tandard was proces s ed and approved for s ubm ittal to ANSI by Accredited Standards Com m ittee on
Ins ulators for Electric Power Lines , C29. Com m ittee approval of the s tandard does not neces s arily im ply
that all com m ittee m em bers voted for approval. At the tim e it approved this s tandard, the ASC C -29
Com m ittee had the following m em bers :
Rob Christman, Chairman
Steve Griffith, Secretary
Organiz ation Represented: Nam e of Representative:
Edis on Electric Ins titute B. Freim ark
R. Chris tm an
E. Cleckley
M. Garrels
W. Avery
J. Varner (alt)
R. Kluge (alt)
G. Obenchain (alt)
Ins titute of Electrical and Electronic Engineers T. Gris ham
J. Hildreth
A. Jagtiani
J. Kuffel
A. Phillips
E. Gnandt (alt)
National Electrical Manufacturers As s ociation P. Maloney
A. Baker
R. A. Berns torf
G. Powell
G. A. Stewart
E. Kres s (alt)
Z. Lodi (alt)
E. Niedos pial (alt)
A. Schwalm (alt)
Tennes s ee Valley Authority J. Nels on
Wes tern Area Power Adm inis tration R. Clark
© Copyright 2013 by National Electrical Manufacturers As s ociation
TABLE OF CONTENTS
C29.7-1996 (R2002, R2012)
Page v
Page
FOREWORD ...............................................................................………………..iv 1 SCOPE ................................................................................................................. 1
2 REFERENCED AMERICAN NATIONAL STANDARDS .................................... 1
3 DEFINITIONS ...................................................................................................... 1
4 GENERAL ............................................................................................................ 1 5 MATERIALS ......................................................................................................... 1
6 DIMENSIONS AND CHARACTERISTICS ......................................................... 2 7 MARKING ............................................................................................................ 5
8 SAMPLING, INSPECTION, AND TESTS .......................................................... 5 8.1 General ......................................................................................................................................................... 5
8.2 Des ign Tes ts ............................................................................................................................................... 5
8.2.1 Low-frequency Dry Flas hover Tes t ........................................................................................................... 5
8.2.2 Low-frequency Wet Flas hover Tes t .......................................................................................................... 5
8.2.3 Critical Im puls e Flas hover Tes t–Pos itive................................................................................................ 5
8.2.4 Radio-influence Voltage Tes t .................................................................................................................... 5
8.2.5 Therm al Shock Tes t .................................................................................................................................... 5
8.3 Quality Conform ance Tes ts ....................................................................................................................... 6
8.3.1 Vis ual and Dim ens ional Tes ts .................................................................................................................. 6
8.3.2 Poros ity Tes t ................................................................................................................................................. 6
8.3.3 Galvanizing Tes t........................................................................................................................................... 6
8.3.4 Cantilever-Strength Tes t............................................................................................................................. 6
8.4 Routine Tes ts ............................................................................................................................................... 6
8.4.1 Routine Flas hover Tes t............................................................................................................................... 6
8.4.2 Routine Cantilever Tes t .............................................................................................................................. 6
TABLES 1 Dimensions and Characteristics of Line Post Insulators ................................................................. 3
2 Neck Designations and Dimensions ...................................................................................................... 5
FIGURES 1 CLASSES 57-1, 57-2, AND 57-3 ................................................................................................................ 7
2 CLASSES 57-4, 57-5, AND 57-6 ................................................................................................................ 8
3 CLASSES 57-11, 57-12, 57-13, 57-14, 57-15, AND 57-16 ................................................................... 9
4 CLASSES 57-21, 57-22, 57-23, 57-24, 57-25, AND 57-26 .................................................................10
5 CLASSES 57-31, 57-32, 57-33, 57-34, 57-35, AND 57-36 .................................................................10
6 CAP DIMENSIONS-VERTICAL CLAMP ...................................................................................................11
7 CAP DIMENSIONS-HORIZONTAL CLAMP .............................................................................................12
8 CAP GAUGE.................................................................................................................................................13
9 BASE RECESS AND THREAD DIMENSIONS ..........................................................................................14
10 GAIN BASE DETAILS..................................................................................................................................15
APPENDIX .......................................................................................................... 16
© Copyright 2013 by National Electrical Manufacturers As s ociation
C29.7-1996 (R2002, R2012)
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© Copyright 2013 by National Electrical Manufacturers As s o ciation
C29.7-1996 (R2002, R2012)
Page 1
AMERICAN NATIONAL STANDARD ANSI/NEMA C29.7-1996
(R2002, R2012)
Wet Process Porcelain Insulators—High-Voltage Line-Post Type
1 SCOPE This s tandard covers high-voltage line-type ins ulators m ade of wet-proces s porcelain and us ed in the
trans m is s ion and dis tribution of electrical ene rgy.
2 REFERENCED AMERICAN NATIONAL STANDARDS
This s tandard is intended for us e in conjunction with the following Am erican National Standards . When
thes e s tandards are s upers eded by a revis ion approved by the Am erican National Standards Ins titute, Inc.
the revis ion s hall apply.
ANSI C29.1-1988 (R2012) Test Methods for Electrical Power Insulators
ANSI Z55.1-1967 (R1973) Am erican National Standard Gray Finishes for Industrial Apparatus and
Equipm ent
ASTM A153-82 Specification for Zinc Coating (Hot Dip) on Iron and Steel Hardware
3 DEFINITIONS
3.1 See s ection 2 of ANSI C29.1-1988 (R2012) for definitions of term s .
3.2 As us ed in the title and els ewhere in this s tandard, the term insulator or insulators s hall m ean any
of the as s em blies s hown whether they cons is t of a s ingle piece of porcelain together with its m etal parts or
of two or m ore s uch porcelains bolted together to form a rigid as s em bly.
As us ed in this s tandard, the term unit, units, insulator unit, or insulator units s hall m ean any s ingle-piece
porcelain as s em bly together with its m etal parts .
4 GENERAL
4.1 Ins ulators s hall conform in all res pects to the requirem ents of this s tandard. The text and figures
s upplem ent each other and s hall be cons idered part of this s tandard.
4.2 Manufacturer’s drawings , if furnis hed, s hall s how the outline of the ins ulators , together with all
pertinent dim ens ions . Any variations in thes e dim ens ions due to m anufacturing tolerances s hall be
indicated.
5 MATERIAL
5.1 The ins ulators s hall be m ade of g ood com m ercial-grade wet-proces s porcelain.
© Copyright 2013 by National Electrical Manufacturers As s o ciation
C29.7-1996 (R2002, R2012)
Page 2
5.2 The entire s urface of the ins ulator, with the exception of a firing s urface, s hall be glazed. The entire
s urface s hall be relatively free from im perfections . Color is not a part of this s tandard. If gray is required, it
s hall be in accordance with ANSI Z55.1 -1967 (R1973), and conform to Muns ell notation 5BG 7.0/0.4 with
the following tolerances :
1) Hue: ± 12 (3G to 7B)
2) Value: ± 0.5
3) Chrom a: -0.2 to +0.6
5.3 Metal parts s hall be m ade of a good com m ercial grad e of m alleable iron, ductile iron, s teel, or
alum inum . Ferrous parts , other than s tainles s s teel, s hall be galvanized in accordance with ASTM A153.
6 DIMENSIONS AND CHARACTERISTICS
6.1 Figures 1 through 5 (s ee pages 8-11) are drawings of ins ulator types . Dim ens ions and
characteris tics of the ins ulators s hall be in accordance with thes e figures and Table 1.
6.2 When s pecified, neck des ignations s hall be as s hown in table 2.
© Copyright 2013 by National Electrical Manufacturers As s o ciation
C29.7-1996 (R2002, R2012)
Page 3
Table 1–Dimensions and Characteristics of Line Post Insulators
Low f requency
f lashover Positive critical
impulse f lashover Radio inf luence voltage Leakage
distance Dry arcing
distance Ref erence
height/length Cantilever
strength Nominal diameter
insulating part Center hole nominal
threaded size
Clas s
Dry kV
Wet kV
kV
Tes t voltage1
kV Max RIV
2
m icrovolts
Inches
Inches
Inches
Pounds
Inches
Inches Figure
Vertical tie-top type 57-1 70 50 120 15 100 14 6.5 9 2800 5.5 3/4 1 57-2 100 70 160 22 100 22 9.5 12 2800 6 3/4 1 57-3 125 95 200 30 200 29 12.25 15 2800 6.5 3/4 1 57-4 140 110 230 44 200 40 14.5 17 2800 7 3/4 2 57-5 160 130 265 44 200 45 17.25 20 2800 7.5 3/4 2 57-6 180 150 300 44 200 53 19.25 23.5 2800 8 7/8 2
Vertical clamp-top type 57-11 70 50 120 15 100 14 6.5 10 2800 6 3/4 3 57-12 100 70 160 22 100 22 9.5 13 2800 6.5 3/4 3 57-13 125 95 200 30 200 29 12.25 16 2800 6.5 3/4 3 57-14 140 110 230 44 200 40 14.5 18.5 2800 7 3/4 3 57-15 160 130 265 44 200 45 17.25 21.5 2800 7.5 3/4 3 57-16 180 150 300 44 200 53 19.25 24.5 2800 8 7/8 3
Horizontal cup-base type 57-21 70 50 120 15 100 14 6.5 11 2800 6 3/4 4 57-22 100 70 160 22 100 22 9.5 14 2800 6.5 3/4 4 57-23 125 95 200 30 200 29 12.25 16.5 2800 6.5 3/4 4 57-24 140 110 230 44 200 40 14.5 20 2800 7 3/4 4 57-25 160 130 265 44 200 45 17.25 22.5 2800 7.5 3/4 4 57-26 180 150 300 44 200 53 19.25 25 2800 8 7/8 4
Horizontal gain-base type 57-31 70 50 120 15 100 14 6.5 11 2800 6 - 5 57-32 100 70 160 22 100 22 9.5 14 2800 6.5 - 5 57-33 125 95 200 30 200 29 12.25 16.5 2800 6.5 - 5 57-34 140 110 230 44 200 40 14.5 20 2800 7 - 5 57-35 160 130 265 44 200 45 17.25 22.5 2800 7.5 - 5 57-36 180 150 300 44 200 53 19.25 25 2800 8 - 5
Note 1: Low frequency tes t voltage, rm s to ground
Note 2: Maxim um RIV at 1000kHz, m icrovolts
© Copyright 2013 by National Electrical Manufacturers As s o ciation
C29.7-1996 (R2002, R2012)
Page 4
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© Copyright 2013 by National Electrical Manufacturers As s o ciation
Table 2
Neck Designations and Dimensions
C29.7-1996 (R2002, R2012)
Page 5
Des ignatio
n
Diam eter
Groove-Height
Relations hip
As Applicable (inches ) Letter (inches ) Minim um Maxim um
A 1-3/4 ± 1/8 - - C 2-14 ± 1/8 9/16 7/8 F 2-7/8 ± 1/8 9/16 7/8 J 3-1/2 ± 1/8 1/4 5/8 K 4 ± 1/8 1/4 5/8 N 6 ± 1/8 9/16 7/8
7 MARKING Each ins ulator s hall bear a s ym bol identifying the m anufacturer and giving the year of m anufacture . The
m arking s hall be legible and durable.
8 SAMPLING, INSPECTION, AND TESTS
8.1 General. Tes ts des cribed in 8.2 s hall be required only on Ins ulators of new des igns . Tes ts
des cribed in 8.3 s hall be required on each lot of ins ulators . Tes ts des cribed in 8.4 s hall be m ade on each
ins ulator.
8.2 Des ign Tes ts
8.2.1 Low-frequency dry flas hover tes t. Three ins ulators s hall be s elected at random and tes ted in
accordance with 4.2 of ANSI C29.1-1988 (R2012). Failure of the average dry flas hover value of the three
ins ulators to equal or exceed 95% of the rated dry flas hover value, as given in Table 1, s hall cons titute
failure to m eet the requirem ents of this s tandard.
8.2.2 Low-frequency wet flas hover tes t. Three ins ulators s hall be s elected at random and tes ted in
accordance with 4.3 of ANSI C29.1-1988 (R2012). Failure of the average wet flas hover value of the three
ins ulators to equal or exceed 90% of the rated wet flas hover value, as g iven in table 1, s hall cons titute
failure to m eet the requirem ents of this s tandard.
8.2.3 Critical im puls e flas hover tes ts –pos itive. Three ins ulators s hall be s elected at random for the
critical im puls e flas hover tes t, pos itive, and tes ted in accordance with 4.7 of ANSI C29.1-1988 (R2012).
Failure of the average critical im puls e flas hover value of the three ins ulators to equal or exceed 92% of the
rated critical im puls e flas hover value, as given in table 1, s hall cons titute failure to m eet the requirem e nts of
this s tandard.
8.2.4 Radio-influence voltage tes t. Three ins ulators s hall be s elected at random and tes ted in
accordance with 4.9 of ANSI C29.1-1988 (R2012). If one or m ore ins ulators fail to m eet the requirem ents
given in table 1, three additional ins ulators s hall be s elected at random and tes ted. Failure of one or m ore
of thes e additional ins ulators s hall cons titute failure to m eet the requirem ents of this s tandard.
8.2.5 Therm al s hock tes t. Three ins ulators s hall be s elected at random and te s ted for ten com plete
cycles in accordance with 5.5 of ANSI C29.1 -1988 (R2012). The tem perature of the hot water bath s hall be
approxim ately 150°F (66°C), and the tem perature of the cold water bath s hall be approxim ately 39°F (4°C).
© Copyright 2013 by National Electrical Manufacturers As s o ciation
C29.7-1996 (R2002, R2012)
Page 6
If one or m ore ins ulators fail, three additional ins ulators s hall be s elected at random and tes ted. Failure of
one or m ore of thes e additional ins ulators s hall cons titute failure to m eet the requirem ents of this s tandard.
8.3 Quality Conform ance Tes ts
8.3.1 Vis ual and dim ens ional tes ts . Conform ity with 5.2 m ay be determ ined by vis ual ins pection. All
ins ulators not conform ing to 5.2 fail to m eet the requirem ents of this s tandard.
Three ins ulators s hall be s elected at random from the lot and their dim ens ions checked agains t the
dim ens ions on the m anufacturer’s drawing. Failure of m ore than one of thes e ins ulators to conform within
m anufacturing tolerances to the dim ens ions on this drawing s hall cons titute failure of the lot to m eet the
requirem ents of this s tandard.
8.3.2 Poros ity tes t. Specim ens s hall be s elected from ins ulators des troyed in other tes ts and tes ted in
accordance with 5.4 of ANSI C29.1-1988 (R2012). Penetration of the dye into the body of the dielectric s hall
cons titute failure of the lot to m eet the requi rem ents of this s tandard.
8.3.3 Galvanizing tes t. Three pieces repres entative of each type of galvanized hardware us ed with the
ins ulators s hall be s elected at random and tes ted in accordance with Section 6 of ANSI C29.1-1982
(R2012). Five to ten m eas urem ents s hall be uniform ly and random ly dis tributed over the entire s urface.
Both the average thicknes s value for each individual s pecim en and the average of the entire s am ple s hall
equal or exceed the following:
Average of Entire Sam ple Average of Individual Specim en Hardware (except nuts /bolts ) 3.4 m il 3.1 m il Nuts /bolts 2.1 m il 1.7 m il
If the average of one s pecim en, or if the average of the entire s am ple, fails to com ply with the above, ten
additional pieces of the s am e type of hardware s hall be s el ected at random and tes ted. Failure of the
retes t s am ple to com ply with the m inim um thicknes s criteria s hall cons titute failure of the lot to m eet the
requirem ents of this s tandard.
8.3.4 Cantilever-s trength tes t. Three ins ulators s hall be s elected at random and tes ted in accordance
with 5.1.3 of ANSI C29.1-1982 (R2012). Failure of the average s trength of the three ins ulators to m eet the
s trength requirem ent given in the applicable figure, or failure of any one ins ulator to equal 85% of that
s trength requirem ent, s hall cons titute failure of the lot to m eet the requirem ents of this s tandard.
8.4 Routine Tes ts
8.4.1 Routine flas hover tes t. Each ins ulator s hall be s ubjected to a routine flas hover tes t in accordance
with claus e 7.1 of ANSI C29.1-1982 (R2012). For this tes t, an electrode s hall be placed on each s ide of,
and adjacent to, the porcelain barrier. All ins ulators that puncture fail to m eet the requirem ents of this
s tandard.
8.4.2 Routine cantilever tes t. Each as s em bled ins ulator s hall be s ub jected to a cantilever proof tes t.
The load applied s hall be not les s than 40% of the rated cantilever s trength. The force s hall be applied at
the Line end, only and s hall be repeated for each of the four quadrants . All ins ulators that fail do not m eet
the requirem ents of this s tandard.
© Copyright 2013 by National Electrical Manufacturers As s o ciation
Note 1: “F” neck
Note 2: See figure 9A for bas e threading .
Note 3: All dim ens ions are in inches .
Note 4: Top wire groove s hall s eat a 1-15/16-inch diam eter m andrel.
Note 5: Side-wire groove s hall s eat a 1-15/16-inch diam eter m andrel.
FIGURE 1
VERTICAL TIE-TOP TYPE-F NECK,
CLASSES 57-1, 57-2, AND 57-3
C29.7-1996 (R2002, R2012)
Page 7
© Copyright 2013 by National Electrical Manufacturers As s o ciation
C29.7-1996 (R2002, R2012)
Page 8
Note 1: “N” neck
Note 2: See figure 9A for Clas s es 57-4 and 57-5 bas e threading and figure 9B for Clas s 57 -6 bas e
threading.
Note 3: All dim ens ions are in inches .
Note 4: Top wire groove s hall s eat a 1-7/16-inch diam eter m andrel.
FIGURE 2
VERTICAL TIE-TOP TYPE-N NECK,
CLASSES 57-4, 57-5, AND 57-6
© Copyright 2013 by National Electrical Manufacturers As s o ciation
C29.7-1996 (R2002, R2012)
Page 9
Note 1: All dim ens ions are in inches
Note 2: See figure 9A for Clas s es 57-11, 57-12, 57-13, 57-14 and 57-15 bas e threading and figure 9B for
Clas s 57-16 bas e threading.
Note 3: See figure 6 for cap dim ens ions .
FIGURE 3
VERTICAL CLAMP-TOP TYPE,
CLASSES 57-11, 57-12, 57-13, 57-14, 57-15, AND 57-16
© Copyright 2013 by National Electrical Manufacturers As s o ciation
C29.7-1996 (R2002, R2012)
Page 10
Note 1: All dim ens ions are in inches
Note 2: See figure 9A for Clas s es 57-21, 57-22, 57-23, 57-24 and 57-25 bas e threading and figure 9B for
Clas s 57-26 bas e threading.
Note 3: See figure 7 for cap dim ens ions .
FIGURE 4
HORIZONTAL CLAMP TOP-CUP BASE TYPE,
CLASSES 57-21, 57-22, 57-23, 57-24, 57-25, AND 57-26
Note 1: All dim ens ions are in inches
Note 2: See figure 10A for Clas s es 57 -31, 57-32, 57-33, and 57-34 bas e details and figure 10B for Clas s
57-35 and 57-36 bas e details .
Note 3: See figure 7 for cap dim ens ions .
FIGURE 5
HORIZONTAL CLAMP TOP GAIN BASE TYPE,
CLASSES 57-31, 57-32, 57-33, 57-34, 57-35, AND 57-36
© Copyright 2013 by National Electrical Manufacturers As s o ciation
C29.7-1996 (R2002, R2012)
Page 11
Dimension Value a (See note 1) b (See note 1) c 15/32 m in. (See note 2) d 11/32 (See note 2) e (See note 1) f 5/8 - 11 + 0.015 UFS g (See note 3) h 1/2 m in.
Note 1: To be checked by gauge. See figure 8
Note 2: Maxim um to be determ ined by gauges . See figure 8 .
Note 3: The purpos e of this s tandard is to as s ure interchangeability of clam ps . Trunnion bolts of one
m anufacturer are not neces s arily interchangeable with thos e of another.
FIGURE 6
CAP DIMENSIONS-VERTICAL CLAMP
© Copyright 2013 by National Electrical Manufacturers As s o ciation
C29.7-1996 (R2002, R2012)
Page 12
Dimension Value
c 15/32 (See note 2) d 11/32 m in. (See note 2) e (See note 1) f 5/8 - 11 + 0.015 UFS g (See note 3) h 1/2 m in.
Note 1: To be checked by gauge. See figure 8 .
Note 2: Maxim um to be determ ined by gauges . See figure 8.
Note 3: The purpos e of this s tandard is to as s ure interchangeability of clam ps . Trunnion bolts of one
m anufacturer are not neces s arily interchangeable with thos e of another.
FIGURE 7
CAP DIMENSIONS-HORIZONTAL CLAMP
© Copyright 2013 by National Electrical Manufacturers As s o ciation
C29.7-1996 (R2002, R2012)
Page 13
Note 1: All dim ens ions are in inches .
Note 2: Tolerance of ± 0.002 inch, except as s hown.
FIGURE 8
CAP GAGE
© Copyright 2013 by National Electrical Manufacturers As s o ciation
C29.7-1996 (R2002, R2012)
Page 14
Note: All dim ens ions are in inches .
FIGURE 9
BASE RECESS AND THREAD DIMENSIONS
© Copyright 2013 by National Electrical Manufacturers As s o ciation
C29.7-1996 (R2002, R2012)
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Note: 13/16” s lot width, 15’16” m inim um length
FIGURE 10
GAIN BASE DETAILS
© Copyright 2013 by National Electrical Manufacturers As s o ciation
C29.7-1996 (R2002, R2012)
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APPENDIX (This appendix is not part of Am erican National Standard C29.7-1996 (R2002, R2012), but is included for
inform ation only.)
Packaging
Packaging of ins ulators s hould be s uch as to afford reas onable and proper protection to the ins ulators in
s hipping and handling.
Each box or container s hould be m arked with the num ber of pieces contained therein; the catalog num ber,
or clas s num ber; or des cription of the contents ; and the m anufacturer’s nam e.