The part of the installation on which work is to be carried out shall be disconnected from all sources of supply. The disconnection shall take the form of an air gap or equally effective insulation that will ensure that the point of disconnection does not fail electrically.
Disconnection for work shall be carried out so that:
- Energizing from all energizing directions is prevented
- Adequate isolating distance is obtained
- Isolation assured by visible break point or reliable position indication
- Withdrawable units placed in the disconnected position
- Control and signal circuits are disconnected
- Cables with the risk of residual voltage shall be discharged and short-circuited
- Capacitors with risk of residual voltage shall be discharged and short-circuited