Electrical Grounding Explained

By Pablo Diaz, P.Eng.

Electrical Grounding is the process of removing excess charge on an object by transferring electrical charges from a short circuit between this object and another larger object. This is where the term grounded comes from.

When a charged object has proper grounding, the excess charge is balanced by the transfer of electrical charges between the charged object and a ground, which provides a return path for a charge to safely travel from an object to the earth. This is called a path of least resistance.

The National Electrical Code and many other electrical codes provide rules to govern the proper installation of ground wires in an electrical system to avoid potentially dangerous electric shock accidents. The ground connection provides a path for electric current to flow, for instance from an electric circuit breaker or electrical box through an electrical connection to a cold water pipe that travels into the earth, and that assists the dissipation of energy into the actual ground.

A ground is an infinite reservoir of electrical charges; the ground is capable of transferring electrons to or receiving electrons from a charged object in order to neutralize that object through a neutral wire.

Electrical Grounding of a negatively charged object

Any negatively charged object has an excess of electrical charges or electrons. If it is to have its charge removed, then it will have to lose its excess electrons. Once the excess electrons are removed from the object, there will be equal numbers of protons and electrons within the object and it will have a balance of charge.

To remove the excess of electrons from a negatively charged object, the charged object will have to be connected by a conducting pathway to another object that is capable of receiving those electrical charges. The other object is the ground. And this process is called “Electrical Grounding”.

The process of grounding takes place because excess electrons find each other repulsive.

Grounding is simply an object with significant enough size to share the overwhelming majority of excess charge.

Grounding of a Positively Charged Object

When an object is positively charged how this object is neutralized? We can consider the grounding of a positively charged object. A positively charged object must gain electrical charges in order to acquire an equal number of protons and electrons. By gaining electrons from the ground, the object will have a balance of charge and therefore be neutral.

Grounding is the grounding of a positively charged object and involves the transfer of electrons from the ground into the object. The excess of positive charge on the object attracts electrons from the ground. As in the case of grounding a negatively charged body, the grounding of positively charged electroscope involves charge sharing. The excess positive charge is shared between the object and the ground. And once again, the extent to which an object is willing to share excess charge is proportional to its size. The person is an effective ground because it has enough size to share the overwhelming majority of excess positive charge.

Grounding provides a Conducting Pathway

Any object can be grounded provided that the charged atoms of that object have a conducting pathway between the atoms and the ground.

In our case this pathway or conducting pathway is the “Grounding Conductor, when a metallic equipment metal frame enclosure is to be connected to the earth.

Grounding is simply the removal of excess charges on a body therefore if a charged body is grounded, the excess charges are balanced by charge transference between the body and the ground.

When electrical devices are connected to earth or ground we attach this equipment to a metallic plate or ground rod to ground.

Grounding or Eathing requires a conducting pathway between the ground and the object to be grounded. Electrons will travel along that pathway.