Testing Insulation Resistance

Testing circuit wiring to confirm the condition of the insulation.

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Insulation Resistance

Before energising any new circuit, an insulation resistance test is done to confirm that the insulation of the wires has not been damaged. For 230V AC circuits, a test voltage of 500V DC is applied between the circuit conductors and the resistance of the insulation is recorded.

For new circuits, resistance values should be many 100s of megohms both between the conductors themselves and between those conductors and the installation earth.