Electrical Bonding, Earthing and Grounding

What is the Difference? What are Key Elements for Installation? What is the Purpose?

Electrical Bonding Purpose:

1. Bonding is making a physical low electrical Ohmic value connection between two (2) metallic components.
2. Bonding creates an equipotential value between all metallic components that are bonded together.
3. Bonding is only bonded to metallic components that are not intended to have current flowing during normal operations.

Earthing Purpose:

1. Earthing is a physical low electrical Ohmic value connection from the main metallic connection point in the facility to earth.
2. Earthing creates a path for all metallic components in the facility that are bonded together to have an equipotential value from or too earth.
3. The purpose of Earthing is for personnel protection from a shock hazard within the facility.
4. Earthing can also be used to connect to a normal current carrying conductor such as the Neutral conductor to be used as a reference point between other phase conductors.
5. The term Earthing is mainly used outside of the United States.

Grounding Purpose:

1. Grounding is a physical low electrical Ohmic value connection from the main metallic connection point in the facility to earth.
2. Grounding creates a path for all metallic components in the facility that are bonded together to have an equipotential value from or too earth.
3. The purpose of Grounding is for personnel protection from a shock hazard within the facility.
4. Earthing can also be used to connect to a normal current carrying conductor such as the Neutral conductor to be used as a reference point between other phase conductors.
5. The term Grounding is mainly used outside of the United States.

So, what we have is that bonding is the method of actually making the physical connections between metallic components within the building that is not intended to carry current under normal operating conditions and earthing and grounding connects all the bonded equipment to earth.

To be very clear there is only one connection point in the facility where the connection from earth takes place. They can be many connections from earth to this connection point. All of the different systems connections from earth make up the main grounding electrode system for the facility.

Key elements within the facility are the individual bonding connections themselves. According to the National Electrical Code these individual metallic components cannot use a daisy chain method of bonding. Daisy chain bonding is when you remove a connection from one component it removes the connection to earth. So, this means that the bonding method used for non-Ac equipment frames must have some type of H - tap bonding method in place. If one metallic component is not properly bonded it becomes a personnel shock and fire hazard.

It is very important to verify that no current is flowing on any bonding conductors within the facility. If any current is flowing the facility has electrical ground loops. These electrical ground loops are shock and fire hazards. They may or may not be causing some equipment to fail. when some other power disturbance occurs within or near the facility such as a lightning strike or power surge that rises the voltage level of the facility equipment failures, system failures, downtime and electrical shocks could occur.

Not only are codes, standards and practices required for proper bonding, earthing and grounding but the system bonds need to be verified and tested for current flow.