What type of PE wire should be used in the distribution box

The PE (protective earth) wire in a distribution box must be sized according to fault current, material, and standards, typically matching or exceeding the cross-section of phase conductors, and securely connected to a PE busbar.

Purpose of PE Wire

The P

E conductor is a safety wire that provides a low-resistance path to earth, preventing electric shock and ensuring proper operation of protective devices. It is not normally current-carrying and should never be energized under normal conditions, but it must safely conduct fault currents during short circuits or insulation failures.

Sizing of PE Conductors

The cross-sectional area (c.s.a.) of the PE wire depends on the phase conductor size, material, and earthing system: For copper conductors: If phase conductor ≤ 16 mm²: PE = phase conductor sizeIf phase conductor 16–35 mm²: PE = 16 mm²If phase conductor > 35 mm²: PE = half the phase conductor sizeFor aluminium conductors, the values are slightly larger: 16 mm² minimum for small circuits, up to 35 mm² for larger circuits. Special rules apply for PEN conductors in TN-C-S systems: the cross-section must be at least 10 mm² for copper or 16 mm² for aluminium, as it functions as both neutral and protective conductor. Installation in Distribution BoxesPE conductors are connected to a PE busbar inside the distribution box, which is clearly marked “PE”.

For conductors up to 16 mm², a C-rail (NS35/7. 5) with grounding terminals can be used. For conductors larger than 16 mm², a copper busbar (e.g., 30 x 5 mm) is required, with attachment clamps to ensure secure connection.

All P

E busbars in multi-column switchboards must be interconnected using fish plates or bolts, with the connection cross-section at least equal to the PE conductor. Standards and Safety ConsiderationsPE conductors must comply with IEC 61439-1, DIN EN 61439-1, and VDE 0660-600-1 standards. The conductor must withstand thermal and electrodynamic stresses from fault currents, typically for durations between 0.

2 s and 5 s. Insulating devices should never be included in the PE conductor path to maintain a reliable earth connection.

Summary

To ensure safety and compliance: Use copper or aluminium PE conductors sized according to phase conductors and earthing system. Connect securely to a PE busbar inside the distribution box. Ensure continuous cross-section throughout the switchboard.

Follow IE

C 61439-1 and local standards for installation, fault current rating, and mechanical attachment. This ensures the PE system effectively protects personnel and equipment during fault conditions.