What should be the earth pit resistance value?

Ideally a ground should be of zero ohms resistance. There is not one standard ground resistance threshold that is recognized by all agencies. However, the NFPA and IEEE have recommended a ground resistance value of 5.0 ohms or less.

Why does the earth need low resistance?

The inductance of the ground system dominates during the rapid change of current with time as the current is injected into the earth. A low resistance contact ensures the safe dissipation of this excess energy into the ground.

What is resistance for earthing pit *?

The acceptable Earth Resistance at earth MEEB busbar shall not be more than 1 ohm. For achieving this value more than one earth pits can be installed if necessary depending upon the soil resistivity.

What happens if earth resistance is high?

If the soil has high resistivity, and the ground electrode not sufficiently arranged to offset this, the dissipation of the electrical current running through the system will result in a higher voltage on the grounding system.

What will happen if earth resistance exceeds the permissible limits?

In case the earth resistance exceeds the permissible value, then in the event of an earth fault, the fault current may not reach a sufficient value to operate the protective equipment (such as fuses or relays) and dangerous condition may arise.

What are the factors affecting earth resistance?

Factors affecting on Earth resistivity

• Soil Resistivity. It is the resistance of soil to the passage of electric current.
• Soil Condition.
• Moisture.
• Dissolved salts.
• Climate Condition.
• Physical Composition.
• Location of Earth Pit.
• Effect of grain size and its distribution.

Why is earth’s wire connected to low resistance?

So when there is a fault in the circuit the Earthing wire provide path for the current to flow to ground and the user will not get shock when touches the metal parts . So to drive sufficient current it should offer low resistance to drive more current to ground .

What is the resistance of earth wire?

As per IE rules, the resistance between the consumer earth terminal and the earth continuity conductor must be less than 1 ohms. Earth resistance in a typical domestic wiring must be less than 5 ohms.

What is the importance of earth resistance?

Earth resistance is an important parameter for calculating the amount of short circuit/leakage current dissipating in the ground.

What are the factors affecting the earth resistance?

How is earthing resistance reduced?

There are several simple methods to reduce this resistance. The most effective methods are to increase the depth of the electrode, place several electrodes, and perform a chemical treatment to the soil near the electrodes.

Which one of the following is used in the earth pit to decrease the soil resistance?

Alternate layers of coke and salt are used to increase the effective area of the earth and to decrease the earth’s resistance respectively. Generally, 10 kg of charcoal and 10 kg of salt are used for this purpose.