This International Standard applies to composite suspension/tension insulators consisting of a load-bearing 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 insulators covered by this standard are intended for use as suspension/tension line insulators, but it should be noted that these insulators can occasionally be subjected to compression or bending, for example when used as phase-spacers. This standard can be applied in part to hybrid composite insulators where the core is made of a homogeneous material (porcelain, resin), see Clause 8. The object of this standard is to – define the terms used, – prescribe test methods, – prescribe acceptance criteria. This standard does not include requirements dealing with the choice of insulators for specific operating conditions.