Question 5
State the regulation guiding the following parameters with respect to installation of earthing.
- distance;
- cross-section of earth continuity conductor;
- cross-section of the earth wire;
- electrode;
- earth resistance.
Observation
The expected answers were;
Regulations guiding listed parameters with respect to installation of earthing
- Distance: the distance of the earth electrode from the installation at the premises should not be more than 1.5m.
- Cross-section of the earth continuity conductor: the size of the earth continuity conductor used in the circuit should not be less than (2.5mm2 – 4.0 mm2) copper wire.
- Cross-section of the earth wire: the cross-section of the earth used in the circuit should not be less than half of the cross-section of the main wire of the conductor. The minimum size of the earth wire should be (10 mm2 - 16mm2) copper wire.
- Electrode: the earth electrode and earth wire should be of same material and the electrode should always be buried in the vertical position.
- Earth resistance: the earth resistance of any earthing should be less than1 ohm for better performance.
Many candidates who attempted this question performed poorly. This question is a recall of the regulation on the parameters which is outside the classroom.