MT 4 - TC 99/MT 4

IEC 61936-1:2021 provides requirements for the design and the erection of electrical power installations in systems with nominal voltages exceeding 1 kV AC and nominal frequency up to and including 60 Hz, so as to provide safety and proper functioning for the use intended.
This document does not apply to the design and erection of any of the following:
– overhead and underground lines between separate electrical power installations;
– electrified railway tracks and rolling stock;
– mining equipment and installations;
– fluorescent lamp installations;
– installations on ships according to IEC 60092 (all parts) and offshore units according to IEC 61892 (all parts), which are used in the offshore petroleum industry for drilling, processing and storage purposes;
– electrostatic equipment (e.g. electrostatic precipitators, spray-painting units);
– test sites;
– medical equipment, e.g. medical X-ray equipment.
This document does not apply to the design of prefabricated, type-tested switchgear and high voltage/low voltage prefabricated substation, for which separate IEC standards exist.
This edition includes the following significant technical changes with respect to the previous edition:  
introduction has been rewritten to reflect the status when this document is produced;
the scope has been improved to clarify the application of this document;
missing and obsolete terms and definitions have been updated including improvement of existing terms;
Table 1 has been updated where agreements between supplier and user are needed;
requirements of electromagnetic compatibility have been clarified;
insulation coordination clause (Clause 5) has improved wording for better clarity and the technical content has an updated coordination to the latest versions of the insulation coordination standards;
wording regarding electrical equipment has been improved and made clearer;
subclause for fuses has been improved and reworded;
requirements have been added for labelling when multiple sources are required to be disconnected;
missing requirements for GIS have been reintroduced;
subclause regarding ventilation (HVAC) has been improved;
figures in Clause 7 have been updated and moved to the corresponding subclause;
requirements for transformer installations have been improved including adjustment of editorial typing-errors;
clause on protection, automation and auxiliary systems has been restructured and improved;
protection against lightning strokes has been extended;
clarification of content due to the distinction between erection (and providing electrical safety for the intended use of the electrical power installation) and subsequent activities such as maintenance and repair with safe working procedures;
where no provincial, national or regional regulations are available for safe working procedures, an informative guideline is provided in Annex F. This replaces the former parts of Figure 3 in Clause 7.

IEC 61936-1:2010 provides common rules for the design and the erection of electrical power installations in systems with nominal voltages above 1 kV a.c. and nominal frequency up to and including 60 Hz, so as to provide safety and proper functioning for the use intended. For the purpose of interpreting this standard, an electrical power installation is considered to be one of the following:
a) Substation, including substation for railway power supply;
b) Electrical installations on mast, pole and tower; Switchgear and/or transformers located outside a closed electrical operating area;
c) One (or more) power station(s) located on a single site. The installation includes generators and transformers with all associated switchgear and all electrical auxiliary systems. Connections between generating stations located on different sites are excluded;
d) The electrical system of a factory, industrial plant or other industrial, agricultural, commercial or public premises. The electrical power installation includes, among others, the following equipment: rotating electrical machines; switchgear; transformers and reactors; converters; cables; wiring systems; batteries; capacitors; earthing systems; buildings and fences which are part of a closed electrical operating area; associated protection, control and auxiliary systems; large air core reactor. NOTE: In general, a standard for an item of equipment takes precedence over this standard. This standard does not apply to the design and erection of any of the following:
- overhead and underground lines between separate installations;
- electric railways;
- mining equipment and installations;
- fluorescent lamp installations;
- installations on ships and off-shore installations;
- electrostatic equipment (e.g. electrostatic precipitators, spray-painting units);
- test sites;
- medical equipment, e.g. medical X-ray equipment.
This standard does not apply to the design of factory-built, type-tested switchgear for which separate IEC standards exist. This standard does not apply to the requirements for carrying out live working on electrical installations. This second edition cancels and replaces the first edition, published in 2002. It constitutes a technical revision. The main changes with respect to the previous edition are listed below:
- new table of references for additional agreements between manufacturer/contractor/planer and user/orderer/owner (4.1.2);
- addition of minimum clearances in air not standardized by IEC but based on current practice in some countries (Annex A);
- deletion of nominal voltages (Table 1, Table 2, Clause 5);
- addition of regulations for fuses (6.2.15);
- simplification of regulations for escape routes (7.5.4);
- deletion of special regulations for operating aisles (7.5.4);
- modification of clearances for fire protection (Table 3);
- modification of safety criteria for earthing systems (10.2.1);
- modified curves of permissibly touch voltages (Figure 12, Annex B);
- deletion of numbering of subclauses without headlines;
- change of "should" to "shall" in many cases or change of subclauses with "should" to a note. The contents of the corrigendum of March 2011 have been included in this copy.