The purpose of earthing for work is to prevent that dangerous energizing occurs at the work location, for example by unintentional energizing by incorrect switching, feeding from local production, backup power, residual voltage, induction, and more.
For all high voltage installations, all parts that are to be worked on shall be earthed and short-circuited. Earthing and short-circuiting may not be necessary in extra low and low voltage installations, except if there is a risk of the installation being made live.
The earthing and short-circuiting equipment or devices shall be visible, whenever possible, from the work location. Otherwise, the earth connections shall be applied as close to the work location as is reasonably practical.
Where during the course of the work activity conductors are to be broken or joined and there is danger from potential differences on the installation, suitable measures such as bonding or earthing shall be taken at the work location before the conductors are broken or joined.
Precautions shall be taken to ensure that the earths remain secure during the time the work is in progress.
Parts of the electrical installation which can remain charged after complete disconnection, for example capacitors and cables, shall be discharged using suitable devices.
Earthing tools
Earthing tools shall conform to present standards and be checked in accordance with the manufacturer’s instructions. Earthing tools shall be applied and removed with the intended equipment.
Earthing and short-circuiting equipment shall be adequately matched to the fault rating of the electrical installation where they are installed.
It is essential to discard and not use earthing tools that have been subjected to short-circuit or are damaged.
Earthing and short-circuiting equipment or devices shall be first connected to the earthing point and then to the components to be earthed. When the equipment shall be removed, the procedure is reversed; the part in contact with the component is removed first and then the earth.