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BRITISH STANDARD|BS EN 60168:1995 IEC 60168:1994(3)

BRITISH STANDARD|BS EN 60168:1995 IEC 60168:1994(3)

6 Fixing arrangements
The fixing arrangements of standard post insulators and post insulator units shall be in accordance with
the Table I to Table VI.
Where applicable, fixing holes shall be equally spaced on the appropriate pitch circle, which shall be
concentric with the axis of the insulator. Holes in top and bottom fittings shall be in line, unless otherwise
specified, and they shall be so arranged as to permit the use of normal hexagon bolted heads and nuts.
The tapped holes shall be of standard size except that the diameter may be oversize by not more
than 0,25 mm (0,01 in). They shall be suitable for steel bolts having standard dimensions after galvanizing.
The length of full thread shall be not less than the nominal bolt diameter for outdoor post insulators and
indoor post insulators of ceramic material or glass and not less than 1,5 times the nominal bolt diameter
for indoor post insulators of organic material. The threads of tapped holes in galvanized fittings may be cut
after galvanizing.
Standard insulators shall have ISO metric threads except for pedestal post insulator units where Unified
Coarse (UNC) threads may be used.
The axial distance between the bottom mounting face of an insulator of organic material and the lower end
of the bottom thread (dimension l in Figure 2) is assumed to be zero unless otherwise agreed between the
manufacturer and the purchaser. In this case the values in the last column of Table II shall apply.
NOTE 1 Post insulators at present in service, although they are in accordance with the other characteristics specified in this
standard, may have Whitworth or American National Coarse threads.
NOTE 2 To permit interchangeability, fixing screws may be supplied with each post insulator.
7 Plan of the standard
The specified characteristics are given in the following tables:
— Indoor post insulators of ceramic material or glass and
with internal metal fittings
Table I.
— Indoor post insulators of organic material and with
internal metal fittings
Table II.
— Outdoor cylindrical post insulators of ceramic material or
glass and with internal metal fittings
Table III.
— Outdoor cylindrical post insulators of ceramic material or
glass and with external metal fittings
Table IV.
— Outdoor pedestal post insulator units of ceramic material
or glass
Table V to Table VIII.
— Fixing arrangements Table IA, Table IIA, Table IIIA,
Table IVA, Table VA and Table VIA.
In tables which relate to complete post insulators, all insulators of the same lightning impulse withstand
voltage are grouped together. In tables relating to pedestal post insulator units, the units are arranged
with the type numbers in sequence.
The basis of standardization of cylindrical post insulators is the full specification of the complete post
insulator.
The basis of standardization of pedestal post insulators is the full specification of the units in Table V
to Table VIII. Complete pedestal post insulators are composed of one or more of these units. For stacks of
more than one unit, it is often possible to reach a given voltage and strength rating in a number of
alternative ways. The alternative pedestal post insulators may differ in certain respects, such as stiffness,
radio interference performance, etc., and it may be necessary to decide the most suitable composition of the
post insulator by agreement between the manufacturer and the purchaser. Examples of combinations of
units to form pedestal post insulators are given in Appendix A; other combinations are also possible.
8 Designation of post insulators
Each standard post insulator is assigned a reference symbol which indicates:
NOTE 1 The designation does not always fully specify the insulator, as sometimes alternative constructions are included in the
standard.
NOTE 2 The strength class and lightning impulse withstand voltage designations are not used for pedestal post insulator units,
which are designated by a reference number.
Examples: “IEC post insulator Type J4-125” indicates an indoor post insulator of ceramic material or glass of strength Class 4 and
with lightning impulse withstand voltage 125 kV.
“IEC post insulator Type JO8-60” indicates an indoor post insulator of organic material of strength Class 8 and with lightning impulse
withstand voltage 60 kV.
“IEC post insulator Type H16-75” indicates an outdoor cylindrical post insulator of ceramic material or glass with internal metal
fittings of strength Class 16 and with lightning impulse withstand voltage 75 kV.
“IEC post insulator Type C6-1050-I” indicates an outdoor cylindrical post insulator of ceramic material or glass with external metal
fittings of strength Class 6 and with lightning impulse withstand voltage 1 050 kV and Class I creepage distance.
“IEC post insulator Type PD-1050” indicates an outdoor pedestal post insulator of ceramic material or glass of strength Class D and
with lightning impulse withstand voltage 1 050 kV.
— Insulator type:
indoor post insulator of ceramic material or glass designation J
indoor post insulator of organic material designation JO
outdoor cylindrical post insulator of ceramic material or glass and with internal
metal fittings
designation H
outdoor cylindrical post insulator of ceramic material or glass and with external
metal fittings
designation C
outdoor pedestal post insulator unit of ceramic material or glass designation E
outdoor pedestal post insulator of ceramic material or glass designation P
— Mechanical strength class (see Clause 4):
2 – 4 – 8 – 16 – 25 for indoor post insulators of ceramic material or glass
2 – 4 – 6 – 8 – 10 – 16 – 25 for indoor post insulators of organic material
2 – 4 – 8 – 16 – 31,5 for outdoor cylindrical post insulators of ceramic material or glass and
with internal metal fittings
2 – 4 – 6 – 8 – 10 – 12,5 – 16 –
20 – 25 – 31,5 – 40
for outdoor cylindrical insulators of ceramic material or glass and with
external metal fittings
A – B – C – D – E for outdoor pedestal post insulators of ceramic material or glass
— Creepage distance Class I - II for outdoor cylindrical insulators of ceramic material or glass and with
external metal fittings
— Lightning impulse withstand voltage (in kilovolts) 60 to 2 550.

Section 2. Examples of insulator types

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