In Electrical Engineering, earthing refers to the method of creating low impedance path to the ground. Generally, a rod (known as earth rod) is driven into the earth to which earth conductor is tied.
MCQ on Electrical Earthing
The earthing rod orientation in the pit should be:
- 45°
- Horizontal
- Vertical
- 75°
Correct answer: 3. Vertical
Ground resistance value for sensitive installations is:
- Less than 5 ohms
- 5 – 25 ohms
- 50 ohm
- 100 ohms
Correct answer: 1. Less than 5 ohms
Doubling the length of the ground electrode will cause resistance to:
- Increase by 10%
- Decrease by 10%
- Increase by 40%
- Decrease by 40%
Correct answer: 4. Decrease by 40%
The easiest method for earth resistance measurement:
- Fall of potential
- Selective measurement
- Stakeless measurement
- All are equally easy
Correct answer: 3. Stakeless measurement
Statement: Which one of the following is used in earth pit:
- Aluminum and Iron
- Graphite and Silver
- Graphite and magnesium
- Salt and charcoal
Correct answer: 4. Salt and charcoal