How to test earth continuity with a multimeter

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Electricity involves the motion of electrically charged particles through metallic wires, and it has allowed mankind essential technologies such as lighting and heating. Electrical currents flow from high voltage to zero voltage, which is also called ground or earth voltage. The continuity of this voltage path is essential to the safe functioning of any electrical device. A digital multimeter is a portable unit capable of measuring resistance, voltage and current. It can also be used to check the safe functioning of electrical appliances by measuring the appliances earth continuity.

Switch off the appliance that needs to be checked and remove the electrical plug from the outlet socket. To be safe, wait one hour for any capacitors to discharge. Using a screwdriver, remove screws, and open back of the appliance where the power line enters.

Locate the earth wiring. This will normally be a thick green wire attached to the casing of the appliance.

Switch on the multimeter, and using the dial on the front, select the resistance function. The multimeter will have two probes with metallic pointed ends. Place the probes on either side of the earth wire. The display on the multimeter should show a low resistance of approximately 0.5 Ohms. If the resistance is significantly higher than this, the wire is faulty and needs to be replaced.

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