This International Standard applies to composite line post insulators consisting of a loadbearing cylindrical insulating solid core consisting of fibres – usually glass – in a resin-based matrix, a housing (outside the insulating core) made of polymeric material and end fittings permanently attached to the insulating core. Composite line post insulators covered by this standard are subjected to cantilever, tensile and compressive loads, when supporting the line conductors. They are intended for use on a.c. overhead lines with a rated voltage greater than 1 000 V and a frequency not greater than 100 Hz. The object of this standard is – to define the terms used, – to prescribe test methods, – to prescribe acceptance or failure criteria. This standard does not include requirements dealing with the choice of insulators for specific operating conditions.