Earthing and Bonding in Large Installations - Guidance for Achieving Emc

Earthing and bonding issues become more important in large installations, particularly as equipment is increasingly sensitive to a wide range of electromagnetic disturbances.

For many decades, earthing and bonding measures have mostly been concerned with protection against injury and damage due to electric shock and the effects of lightning.

Now a further objective, that of functional safety, has become equally important.

If equipment fails it is essential that safety is not jeopardised by that failure, as in the case of equipment controlled by programmable logic controllers.

With the multiplicity of electronic systems in buildings, and as the associated equipment operating frequency and bandwidth increase, electromagnetic compatibility has become a major issue to deal with.

Consequently earthing and bonding practices have had to be reviewed in order to cope with new problems.

Purchasing CE marked equipment compliant with the EMC Directive is not necessarily sufficient to ensure that the whole installation is itself compliant.

This is due to problems with connecting this equipment to the bonding network of the installation. This document focuses on the equipotential bonding and earthing issues.

The topics covered by this document range from the common bonding network, made of the structural metallic parts of a building, down to details on how to connect the screen of a cable properly to the main earthing terminal.

Power supply earthing arrangements are also reviewed.

The modernisation of existing installation, which represents a major part of the installations, is considered with practical ways of improvement.

Finally, the requirement for procedures, their definition and implementation, are addressed, as they are an essential issue to consider in order to ensure long-term compliance of the installations.