According to the PN standard, the following measures of protection against electric shock are distinguished:
- automatic power off,
— double or reinforced insulation,
— electrical separation,
— very low SELV and PELV voltage.
In addition, subsidiary protection measures may be applied.
Each of the above-mentioned means of protection against electric shock should be designed and implemented, that both basic protection is provided, and damage protection.
Other protection measures are allowed for special applications, such as:
- obstacles,
— out-of-reach of hands, and
— isolation of the station,
— ungrounded local compensatory connections,
— electrical separation to supply more than one receiver.
These measures may only be used in electrical installations, which are under the supervision of qualified or instructed persons and in which no unauthorized changes can be made.
Provisions for protection against damage (protection against secondary touch) may be omitted for the following equipment:
— metal brackets for overhead line insulators, which are attached to the building and placed out of reach;
— reinforcement of reinforced concrete columns of overhead lines, where steel reinforcement is not available;
— accessible conductive parts, which due to their small size (approximately 50 mm x 50 Mm) or because of their properties (characteristics) they cannot be grasped or should not be in significant contact with any part of the human body, provided, that the connection to the protective conductor is difficult to make or may be unreliable. These exceptions apply, for example, to. latch, rivets, information plates, cable holders;
— metal pipes or other metal guards protecting the device with double insulation or reinforced insulation.