As an electricity user, it is your duty to make sure your house is properly earthed and bonded. This is to prevent the hazardous effect of faulty current.
The National Electric Code recommends earthing on every new building, and old ones to be earthed during a renovation. An electrician can easily tell if your house has a good earthing and bonding system.
Reasons we earth our houses
- Earthing prevents electric shock by providing a path (protective conductor) which carries the fault currents to the ground.
- To protect electrical appliances from damage arising from faulty currents.
- Prevent the risk of fire outbreaks that may arise from current leakage.
- To maintain a stable voltage in three-phase circuits of an electrical system, even when the load is unstable.
How Earthing works
During house wiring, we usually connect earthing wires from all the sockets to earth links on the distribution board (DB). From the DB, we connect them to the earth plate or electrode.
Whenever there is circuit overload or power surge, current flows through the earth rod to the ground. House earthing protects you from electric shock by providing a conductive plate which carries the faulty current to the ground.
House Earthing Requirement
Electrical grounding requires the following materials:
- Earthing rod.
- Earthing wire.
- Industrial salt.
- Earth link.
The earthing rod has the following features:
- A diameter of 20mm.
- Length of 1500mm.
- An adjustable clamp at the top.
- One conical end structure.
2. Earthing Wire:
Earthing Wires are made of either copper or galvanised iron.
Features of earthing wires
- Excellent conductor.
- Resistant to corrosion
- High tensile strength.
Industrial salt and charcoal
Salt and charcoal are excellent conductors of electricity, they also contain ions and carbon that enhances their conductivity
3. Earthing Tools:
They include spanners and pliers to adjust the clamp
A continuity tester to test for continuity.
Other tools you may need include a shovel, digger, or excavating machine. The earthing pit dimension should be 150cm x 150 cm x 300 cm.
House Earthing Procedures
- To earth a building, you first dig a pit where to bury the ground rod. The pit should be close to the house and about 3 meters deep.
- Put a layer of salt, sand and charcoal and place the earth rod vertically inside the pit. Fill the remaining portion of the pit with salt, sand and charcoal layer.
- Connect the earthing link and the electrode using the earth wire.
- Adjust the clamp using the spanner and plier.
- Once done with the connection, test for continuity using the continuity tester.
How to check house earthing
It is important you know how to check if your house is earthed, and also if it works properly. Although the National Electric Code recommends earthing on every house, older homes may not have it.
If you want to check for your house earthing, use a test lamp, or a multimeter.
To use a test lamp, plug the wires from the lamp into the positive and negative ports of the outlets or socket.
The positive port of the socket should be the right hole, while the negative should be the left hole. ON the switch, the bulb will glow brightly.
Remove the negative wire and insert it into the earthing port of the socket (the top hole).
The bulb should glow brightly as before. If it does not glow, it means there is no earthing in the house. But if the bulb glows and dims, it means that the earthing is faulty.
How to check house earthing with a multimeter.
A multimeter is more accurate when checking the earthing of a house, and you can use them on both alternate current (AC) and direct current (DC).
To check for AC current, move the pointer of the multimeter to AC value. The same applies to DC, you can move the pointer to DC value.
Attach the red probe to the port labelled “V”, “Ω,” or “+”, and the black probe on the port labelled “COM” or “-”.
Insert the red probe on the positive hole, and the black on the negative hole. Check and write the value.
Remove the black probe and insert it into the earthing hole of the socket. Observe the value, it must tally with the earlier value.
If there is less or no value, know that the earthing is faulty.