Definition of Insulators and Insulator Parts
Insulator: An insulator is a device intended to give flexible or rigid support to electric conductors or equipment and to insulate these conductors or equipment from ground or from other conductors or equipment.
An insulator comprises one or more insulator parts to which connecting devices (metal fittings) are often permanently attached.
Shell: A shell is a single insulating member, having a skirt or skirts without cement or other connecting devices, intended to form a part of an insulator or an insulator assembly.
Pin Insulator: A pin type insulator is an insulator having means for rigid mounting on a separable pin.
Post Insulator: A post insulator is an insulator of generally columnar shape, having means for direct and rigid mounting.
Cap and Pin Insulator: A cap and pin insulator is an assembly of one or more shells with metallic cap and pin, having means for direct and rigid mounting.
Line Insulator (Pin, Post): A line insulator is an assembly of one or more shells, having means for semi-rigidly supporting line conductors.
Apparatus Insulator (Cap and Pin, Post): An apparatus insulator is an assembly of one or more apparatus-insulator units, having means for rigidly supporting electric equipment.
Unit: An apparatus-insulator unit is an assembly of one or more shells with attached metal parts, the function of which is to support rigidly a conductor, bus, or other conducting elements on a structure or base member.
Stack: An apparatus-insulator stack is a rigid assembly of two or more apparatus-insulator units.
Suspension Insulator: A suspension insulator is an insulator with attached metal parts having means for non-rigidly supporting electric conductors and includes porcelain disc suspension insulator and silicone rubber suspension insulator.
Unit: A suspension-insulator unit is an assembly of a shell and hardware, having means for non-rigid coupling to other units or terminal hardware.
String: A suspension-insulator string is an assembly of two or more suspension insulators in tandem.
Strain Insulator: A strain insulator is an insulator generally of elongated shape, with two transverse holes or slots.
Spool Insulator: A spool insulator is an insulator of generally cylindrical form having an axial mounting hole and a circumferential groove or grooves for the attachment of a conductor.
Wire Holder: A wire holder is an insulator of generally cylindrical or pear shape, having a hole for securing the conductor and a screw or bolt for mounting.