LINE LEAKAGE TEST

The Line Leakage Test is the fourth test required by the electrical safety testing standards.

The Line Leakage Test is done through a milliammeter with a 1750Ω impedance and a time constant of 225µs (for the EN60335-1 standard) equivalent to the human body. This milliammeter is connected between the neutral conductor and the ground of the DUT for the first line leakage test and then between the phase conductor and the ground of the DUT for the second line leakage test.

A- Line leakage test - Operating mode without insulation transformer:
If the DUT is connected to the earth, the differential breaker of the electrical installation of the building will operate (230 Volts on 1750Ω will drive approximately 130mA).

If the DUT is not connected to the earth, the differential breaker will not operate, but when doing the second measurement (phase/ground), the voltage difference between the housing of the DUT and the earth will be 230 Volts : this voltage is dangerous for the operator. When doing the first measurement, (neutral/ground), the voltage difference between the housing of the DUT and the earth will be only a few volts : this is less dangerous, but not recommended. During this operation mode, it is advised to deny the access to the DUT to anybody without ability, by the use of a safety enclosure or a mechanical, respectively optical barrier.

B- Line leakage test - Operating mode with insulation transformer:

If the DUT is connected to the earth, the differential breaker of the electrical installation of the building won't operate, because of the galvanis insulation between the mains and the DUT. In this operating mode, the ground of the DUT can be permanently connected to the earth, which is safer for the operator.