IEC 61854-2020 Overhead lines – Requirements and tests for spacers.
4 General requirements
The spacer shall be designed as to:
– maintain subconductor spacing (at spacer locations), within any prescribed limits, under all conditions of service excluding short-circuit currents;
– prevent, in subspans between spacers, physical contact between subconductors, except during the passage of short circuit currents when the possibility of contact is accepted provided that the specified spacing is restored immediately following fault clearance;
– withstand mechanical loads imposed on the spacer during installation, maintenance and service (including short circuit conditions) without any component failure or unacceptable permanent deformation;
– avoid damage to the subconductor under specified service conditions;
– be free from unacceptable levels of corona and radio interference under specified service conditions;
– be suitable for safe and easy installation. For the bolted and latching clamp the design shall retain all parts when opened for attachment to the conductor;
– ensure that individual components will not become loose in service;
– be capable of being removed and re-installed on the subconductors without damage to the spacer or subconductors;
– maintain its function over the entire service temperature range;
– avoid audible noise.
Other desirable characteristics, which are not essential to the basic functions of the spacer but which may be advantageous to the purchaser, include:
• verification of proper installation from the ground,
• ease of installation and removal from energized lines
Detailed information on design, best practice and experience of spacers and spacer dampers is given in  1 .
Spacers shall be made of any materials suitable for their purpose. Unless additional requirements are stated, the material shall conform to the requirements of IEC 61 284.
4.2.2 Non-metallic materials
In addition to the requirements of IEC 61 284, the conductivity of the various non-metallic components shall be such that when properly installed
– potential differences between metallic components do not cause damage due to discharge;
– line current including short circuit current and any current flow through the spacer do not
degrade spacer components
4.3 Mass, dimensions and tolerances
Spacer mass and significant dimensions, including appropriate tolerances, shall be shown on contract drawings.
Tolerances applied to the mass and to the dimensions should ensure that the spacers meet their specified mechanical and electrical requirements.
4.4 Protection against corrosion
In addition to the applicable requirements of IEC 61 284, stranded steel wires, if used, shall be protected against corrosion in accordance with IEC 60888.
4.5 Manufacturing appearance and finish
The spacers shall be free of defects and irregularities; all outside surfaces shall be smooth and all edges and corners well-rounded.
The fitting marking requirements of IEC 61 284 shall be applied to all clamp assemblies including those using breakaway bolts.
Correct position of the top of the spacer (for example arrows pointing upward), if necessary, shall also be provided.
4.7 Installation instructions
The supplier shall provide a clear and complete description of the installation procedure and, if required, the in-span location of the spacers.
The supplier shall make available any special installation tool that is required.
All tests described in this document are based on bolted clamps and clamps with helical fixation. If other types of clamps are tested, the clamps should be installed according the suppliers installation instruction.IEC 61854 pdf download.