What is Common Grounding? Examples, Advantages


What is Common Grounding?


Common Grounding is the interconnection between the grounding system of different electrical systems, devices, and machines that provides a common path for all to flow the fault current to the ground. It also helps to access multiple grounding points on the earth for all the different systems. So they can share their own grounding points with each other. The European standard "HD 631 S1-1999E" has fostered the term 'Common Grounding System' or CGS. Here, it consists of the interconnection between the grounding system of all the MV/LV and MV/HV substations.

Common Ground Symbol

common grounding symbol

When a common current-carrying conductor from different systems is connected to a common ground then also it is called a Common Grounding System. It may be a neutral grounding or chassis grounding system. Common grounding mostly exists with a power grounding system and a body grounding system. 

Common Grounding System(CGS)



Here, in the above diagram, you can see the grounding system of two different electrical systems is connected to each other. So they can use both earthing systems each other. They can access only their own earthing system if there is no interconnection between them.


Common Grounding Examples


Some examples of common grounding are,
  • ESD System and Devices
  • Car Chassis Grounding system
  • Substation Grounding system
  • DC Power Supply Systems
  • Multiple Motor or Generator grinding connections in a large plant

In our AC power system, the neutral wire is generally connected to the earth. So we can connect a load between live and earth wire and it will work. But in the case of a DC power system, most of the time nothing from the power source is connected to the ground so here we can not connect a load between the earth and the positive or negative terminal.

Common grounding also helps to make return circuits in some systems. For example, in a car, the negative terminal of the battery is connected to the chassis ground and the negative terminal of all individual loads is also connected to the chassis ground. Here, the common grounding system helps to provide a path for return current from all the loads to the battery. There are no additional conductive wires for negative connection.


Advantages of Common Grounding

  • Reduce Grounding Resistance
  • Make balanced system
  • Reduce Costs to make higher for individuals.
  • Drained most of the fault current as much as possible
  • Makes the system simplified, relaxed design
  • Capability to drain more fault current

It also helps to keep backups if any earthing system is damaged. For example, there are two different electrical systems and each of them has its own grounding system but they are not interconnected to each other. In this case, if any one of the grounding systems is damaged, the electrical system connected to that system will be unprotected. But if both of the systems are interconnected, damaging any one of the grounding systems does not affect the system because it can use another grounding system.

The common grounding system not only has advantages but it has some disadvantages also. Here, we need additional conductors and equipment for the interconnection. If there is a much distance between different systems then the cost also is increased.


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What is Common Grounding? Examples, Advantages What is Common Grounding? Examples, Advantages Reviewed by Author on 11/05/2022 Rating: 5