Importance of Grounding in Household Circuit

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The Importance of Grounding in Household Circuits:

First of all, let us understand what is grounding. Then will see the importance of grounding.

 “Grounding” is an American standard term and is equivalent to “Earthing” which is IEC standard term.

Current flows in a continuous closed path from the source, through a device that uses the power, and back to the source. But electricity need not flow in wires to make the return trip to the source.

It can return through any conducting body including a person that contacts the earth directly or touches a conductive object that in turn enters the earth. And if you accidentally become a link in an electrically live circuit, you’ll get a shock.

Electric Shock due to lack of Grounding
Electric Shock due to lack of Grounding

For example, as shown in the above figure, if the hot wire accidentally became dislodged from a light fixture terminal and came into contact with the light fixture’s metal canopy, which is highly conductive, the fixture would become charged. If you touch the fixture under these conditions, a current leakage or ground fault could occur in which you would provide the path to ground for electric current and you would get a shock.

This shock can be prevented if the circuit had a grounding system. Grounding is achieved when one of the conductive wires serving as part of the circuit path is intentionally given a direct path to the earth, which by virtue of moisture contained within the soil, serves as an effective conductor.

This is why grounding is so important in our household circuits.

What happens if you don’t ground your electrical system?

If you ignore the importance of grounding, then it leads to happen following severe circumstances.

Besides ruining your appliances beyond repair, without grounding, the high amount of electricity in your system can start an electric fire, which puts your property and the lives of your loved ones on the line. Another risk of an overload is an electrical shock that could be painful, or worst, fatal.

Standard Procedures of Grounding:

A “ground” connection to local earth is normally provided for our AC electrical system and for the equipment owned by the utility. Electrical codes require that all circuits 120 volts and above have a system of grounding.

This ground connection must be of the low impedance, or with regard to the generally lower frequencies of AC power, its resistance must be low.

 For example, the US National Electric Code (NEC) specifies an acceptable limit for ground impedance as 25Ω. IEEE Standard 142 recommends a resistance between 1 and 5Ω for the connection between a system’s main ground node and earth for commercial and industrial power systems.

 Your utility will typically target 6-8Ω for the pole connection to the ground. Soil conditions vary widely and will greatly impact ground impedance.

In any case, for the protection of ourselves and any powered equipment, we want this resistance to be as low as possible, and most electricians will shoot for a measured ground impedance of less than 5Ω, typically 2-3Ω.

In fact, troubleshooting problematic power systems usually start with measuring the impedance of the system’s connection to earth ground using special equipment, like a Fall-of-Potential Tester or Clamp-on Tester. In some cases, the remedy might involve bonding additional ground stakes to the system ground.

Clamp Meter used to measure ground resistance
Digital AC/DC Clamp Meter

When all conductive objects are bonded to the same earth ground system with low impedance, the risk of electric shock is minimized, as the voltage is absorbed by the earth and its energy (charge) is dissipated in its large mass.

Grounding Objectives: Importance of Grounding

  1. It limits the voltage rise induced on powered circuits, typically via lightning, line surges, or unintentional contact with higher voltages (limiting the induced voltage magnitude).
  2. For example, a low-impedance connection to earth will limit the voltage that develops if high-voltage conductors fall down onto lower-voltage conductors, which are usually mounted lower to the ground in modern power distribution systems, and this helps to minimize the potential shock to any powered equipment. This low impedance path to earth also helps if a failure occurs within the utility’s distribution transformers.
  3. It provides an alternative path for fault current to flow (safety reasons).
  4. It limits the maximum voltage to the ground under normal operating conditions.
  5. It provides the automatic opening procedure of the circuit using breakers like ELCB if an accident or fault ground occurs on one of its ungrounded conductors.
  6. The fundamental purpose of electrical grounding is to both protect personnel as well as property. An electrical ground prevents conductor voltages from exceeding the rating of the respective conductor insulation.
  7. To minimize disturbances caused by EMI, and RFI that may affect electronic equipment.

Grounding Method:

  • Grounding is commonly accomplished by connecting one of the circuit wires (typically neutral) to the soil or ground by running a wire to a ground rod; a long copper rod is driven directly into the soil.
Earthing System Practice
Earthing System
  • Grounding assures that all metal parts of a circuit that one might come in contact with are connected directly to the earth, maintaining them at zero voltage. During normal operation, a grounding system does nothing. In the event of a malfunction, however, the grounding protects from electric shock or fire.

Results for Poor Grounding:

If the grounding is not carried out properly, it can cause a number of problems.

  • An improper grounding results in a higher potential being created in the equipment that could even move through the insulation gear you use to operate the machine and reach your skin.
  • It can cause a delay in the clearing of faults that will result in insufficient current flow.
  • It causes repeated electric shocks to you whenever you operate the machine.
  • The dangers of a fire caused by leaking electricity are increased exponentially.
  • It can cause a reduction in the operational efficiency of the machine.

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