Electrical installation testing: what gets checked under the HD 384 wiring standard

The test report that accompanies the installer’s declaration (in Greece, the YDE) isn’t a list of tick boxes — it’s a record of real measurements. Below: what gets measured on every installation and what each value means.

Before the instruments: the visual inspection

Inspection always starts with your eyes, not the multimeter. You check that equipment is suitable, that conductor sizes match their protective devices, that circuits are fixed and labelled, that the board is accessible and that the required protective devices are present.

A board with no circuit labelling is a finding in itself: whoever comes after you won’t know what they’re isolating.

Continuity of protective conductors

This confirms that every metal part that should be earthed really is connected to the protective conductor, without a break. The bonding conductors — main and supplementary — are checked too.

It’s the measurement with the greatest practical importance: a break in the protective conductor cancels out all the other protection in the installation.

Insulation resistance

Measured by applying a DC test voltage, it shows whether the conductors’ insulation is still adequate. Low readings point to damp, ageing insulation or a damaged cable inside a conduit.

In practice: disconnect sensitive loads and electronic equipment before testing — otherwise you’ll be measuring the appliance, not the installation, and putting it under stress.

Automatic disconnection of supply — earth fault loop

This checks whether, in the event of an earth fault, the protection will disconnect quickly enough. The earth fault loop impedance is measured and compared with the maximum permitted value for that particular protective device and the required disconnection time.

If the value is higher than permitted, the circuit isn’t properly protected — no matter how new the board is.

Residual current devices (RCDs)

Both the tripping current and the trip time are tested, with instruments and not just the test button. The button confirms that the mechanism moves; it doesn’t confirm that it trips at the right current and in the right time.

Record the rated sensitivity (e.g. 30 mA) next to the measured value. It’s the pair that means something, not the reading on its own.

Earth electrode resistance

The resistance of the earthing system is measured. The acceptable value depends on the type of system and the protective devices used, which is why the measurement is always assessed together with the other results, never in isolation.

Polarity and phase sequence

You confirm that switches and fuses are in the line conductor and not the neutral, that socket outlets are correctly wired and — on three-phase supplies — that the phase sequence is correct.

Recording is part of the measurement

A measurement that wasn’t recorded when it was taken didn’t happen. The test report is filled in on site, circuit by circuit, with the value and the instrument. When that’s done on a phone against the board record, the next periodic inspection starts with the previous values already there for comparison — that’s what ElectroPro does.

Note

Requirements, limits and test methods are set by the applicable standard and legislation in your country (in Greece, ELOT HD 384). This article describes the logic of the inspection; for exact values and procedures, refer to the current text of the standard that applies to you and to your instrument manufacturer’s instructions.