IEC 60364-4-41-2017 pdf download.Low-voltage electrical installations – Part 4-41: Protection for safety – Protection against electric shock.
410.3.2 A protective measure shall Consist of
— an appropriate Combination of a provision for basic protection and an independent provision for fault protection, or
— an enhanced protective provision which provides both basic protection and fault protection.
Additional protection is specified as part of a protective measure under certain conditions of external influences and in certain special locations (see the corresponding Part 7 of lEG 60364).
NOTE 1 For special applications, protective measures wtiich do not follow this concept are permitted (see 410.3.5 and 4 10.3.6).
NOTE 2 An example of an enhanced protective measure is reinforced insulation.
410.3.3 In each part of an installation one or more protective measures shall be applied,taking account of the conditions of external influence.
The following protective measures generally are permitted:
— automatic disconnection of supply (Clause 411),
— double or reinforced insulation (Clause 412),
— electrical separation for the supply of one item of current-using equipment (Clause 413),
— extra-low-voltage (SELV and PELV) (Clause 414).
The protective measures applied in the installation shall be considered in the selection and erection of equipment.
For particular installations see 410.3.4 to 410.3.9.
NOTE In electrical installations the most commonly used protective measure is automalic disconnection of supply
410.3.4 For special installations or locations, the particular protective measures in the corresponding Part 7 of IEC 60364 shall be applied.
410.3.5 The protective measures. specified in Annex B, i.e. the use of obstacles and placing out of reach, shall only be used in installations accessible to
— skilled or instructed persons, or
— persons under the supervision of skilled or instructed persons.
410.3.6 The protective measures, specified in Annex C, i.e.
— non-conducting location,
— earth-free local equipotential bonding,
— electrical separation for the supply of more than one item of current-using equipment, may be applied only when the installation is under the supervision of skilled or instructed persons so that unauthorized changes cannot be made.
410.3.7 If certain conditions of a protective measure cannot be met, supplementary provisions shall be applied so that the protective provisions together achieve the same degree of safety.
NOTE An example of the application of this rule Is given in 4117.
410.3.8 Different protective measures applied to the same installation or part of an installation or within equipment shall have no influence on each other such that failure of one protective measure could impair the other protective measures.
410.3.9 The provision for fault protection (protection against indirect contact) may be omitted for the following equipment:
— metal supports of overhead line insulators which are attached to the building and are placed out of arm’s reach;
— steel reinforced concrete poles of overhead lines in which the steel reinforcement is not accessible;
— exposed-conductive-parts which, owing to their reduced dimensions (approximately 50 mm x 50 mm) or their disposition cannot be gripped or come into significant contact with a part of the human body and provided that connection with a protective conductor could only be made with difficulty or would be unreliable.
NOTE 1 This exemption applies, for example, to bolts, rivets, nameplates and cable clips. NOTE 2 In the USA, all exposed-conductive-parts are bonded to the protective conductor.
— metal tubes or other metal enclosures protecting equipment in accordance with Clause 412.
411 Protective measure: automatic disconnection of supply
411.1 General
Automatic disconnection of supply is a protective measure in which
— basic protection is provided by basic insulation of live parts or by barriers or enclosures, in accordance with Annex A. and
— fault protection is provided by protective equipotential bonding and automatic disconnection in case of a fault in accordance with 411.3 to 411.6.IEC 60364-4-41 pdf download.