Fundamental rule of protection
From Electrical Installation Guide
The fundamental rule of protection against electric shock is provided by the document IEC 61140 which covers both electrical installations and electrical equipment.
Hazardous-live-parts shall not be accessible and accessible conductive parts shall not be hazardous.
This requirement needs to apply under:
- Normal conditions, and
- Under a single fault condition
Various measures are adopted to protect against this hazard, and include:
- Automatic disconnection of the power supply to the connected electrical equipment
- Special arrangements such as:
- The use of class II insulation materials, or an equivalent level of insulation
- Non-conducting location, out of arm’s reach or interposition of barriers
- Equipotential bonding
- Electrical separation by means of isolating transformers