Equipotential bonding systems

Normative requirements for equipotential bonding:

• IEC 60364-4-41 Equipotential bonding

• IEC 60364-5-54 Protective equipotential bonding cable

• IEC 60364-7-701 Bathroom

• IEC 60364-7-702 Swimming pools

• IEC 60364-7-705 Agriculture

• IEC 61784 Telecommunication systems

• IEC 60728-11 Antenna earthing

• IEC 62305 Lightning protection equipotential bonding

• DIN 18014 (foundation earthers) Lightning protection equipotential bonding

A distinction is drawn between "protective equipotential bonding" and"additional protective equipotential bonding".

Protective equipotential bonding

All extraneous conductive parts routed into the building must be connected with one another in order to prevent differences in potential.

Connection of all extraneous conductive parts to the main earthing busbar (MEB)

• Foundation earth electrodes

• Lightning protection earthing

• Conductor for protective equipotential bonding

• Protective conductors within the electrical system

• Metallic water, gas and heating lines

• Antenna earthing

• Metal parts of the building, e.g. air-conditioning ducts, lift guide rails, etc.

• Metal cable shields

Additional protective equipotential bonding

The lightning protection equipotential bonding is an extension of the general protective equipotential bonding. It is achieved by using surge protection devices to create an additional equipotential bonding system for all supply lines of the low-voltage system and in-formation technology.
For installations under special environmental conditions, e.g. potentially explosive areas, or where explicit normative requirements apply, additional protective equipotential bonding must be implemented.
The bodies of all fixed (non-portable) equipment in the immediate vicinity of the place of installation that can be touched at the same time must be connected with all extraneous conductive parts that can be touched at the same time. This includes the functional equipotential bonding cable as per DIN 18014 and the metal main reinforcement in reinforced concrete.

3.1.1 Planning methods

To avoid potential differences, the following system components must be connected, via the main earthing busbar, with equipotential bonding cables in accordance with IEC 60364-5-54 (VDE 0100-540):

• Electrically conductive pipelines

• Other conductive components

• Protective conductors

• Functional earth electrodes

The main earthing rail must be located in the main connection area or close to the building connections. In each building, the earthing cable and the following conductive parts must be connected to the protective equipotential bonding via the main earthing rail:

• Metallic pipelines of supply systems

• Extraneous conductive parts of the building structure

• Metallic central heating and air-conditioning systems

• Protective conductors within the electrical system

• Metallic reinforcements of building structures made of reinforced concrete

The protective equipotential bonding cables must meet the requirements of IEC 60364-441/ IEC 60364-5-54. In the lightning protection equipotential bonding,the cables of the equipotential bonding must be dimensioned for higher currents. Cross-sections must be designed according to IEC 62305 (VDE0185-305).

Requirement to be met by equipotential bonding:
• Must be possible to isolate conductors
• Reliable connection
• Can only be undone with tools

Equipotential bonding according to IEC 60364-4- 41 and IEC 60364-5-54 (DIN VDE 0100410/-540)

Protective conductors must be protected in a suitable manner against mechanical damage, chemical or electrochemical destruction as well as against electrodynamic and thermodynamic forces. Switching devices must not be inserted into the protective conductor. Connections for testing purposes are permitted.

3.1.2 Versions

Each system has different environmental and normative requirements relating to equipotential bonding. To implement equipotential bonding correctly, it is there-fore necessary to select the right components to use. Equipotential busbars and earthing clamps are key components of this kind of installation. In the context of lightning protection equipotential bonding, these must fulfil the requirements and undergo tests as defined in IEC 62561-1 (VDE 0185-561-1).

3.1.2.1 Industrial applications

In an industrial environment, it is particularly important that the products used are thermally and mechanically stable. The OBO type 1802 “BigBar” equipotential bonding rail can be used without problems in these situations as a main earthing or equipotential bonding rail.

OBO 1802 "BigBar": (Figure 3.3)

• Tested with 100 kA (10/350) as per IEC 62561-1

• Can be used indoors and outdoors

• Stainless steel and copper versions available

• 5–20 pin versions available

• Quick mounting with carriage bolts

When connecting metallic pipes to the equipotential bonding, earthing pipe clamps such as OBO type 927 are generally used. These offer a wide range of ad-vantages over pipe clamps during assembly. With their rustproof stainless steel tightening strap, they are suitable for a wide range of pipe diameters and materials.

3.1.2.2 Residential and office buildings

Even though the environmental conditions in residential buildings and office buildings are less challenging, here, too, it is necessary to ensure that no dangerous touch voltages can occur. Equipotential busbars types 1801 and 1809 meet all requirements for main earthing rails or equipotential busbars in these applications. They ensure secure contact for all standard cross-sections. For specialised applications, OBO offers its equipotential bonding system type 1809 NR, made from renewable raw materials with a lead-free contact strip.

3.1.2.3 Potentially explosive areas

Systems in potentially explosive areas require equipotential bonding according to IEC 60079-14 (VDE 0165-1). All the bodies of electrically conductive parts must be connected to the equipotential bonding system. Secure equipotential bonding connections against self-loosening according to IEC 60079-14 (VDE 0165-1) and the Technical Rules for Operating Safety (TRBS) 2152 Part 3.
According to TRBS 2152 Part 3 and IEC 62305-3 (VDE 0185-305-3), the arresting paths of the lightning must be created in such a way that heating or ignitable sparks or spray sparks cannot become the ignition source of the poentially explosive atmosphere.

Potentially explosive areas ATEX zones 1/ 21 and 2/ 22

The unique EX PAS equipotential busbar (equipotential busbar for potentially explosive areas) is used for lightning protection equipotential bonding according to IEC 62305-3 and protective/functional equipotential bonding according to DIN VDE 0100 Part 410/540. Thanks to its patented design, the equipotential bus-bar can be used for installation according to IEC 60079-14 and IEC 62305-3 in the Ex zones 1/21 and Ex zones 2/22.
The lack of ignition sparks in an explosive atmosphere has been tested on the basis of IEC 62561-1 according to explosion group IIC and can thus also be used for the explosion group IIA and IIB. The EX PAS equipotential busbars do not have their own potential ignition source and are thus not subject to the European Directive 2014/34/EU. It is confirmed that the EX PAS type equipotential busbars are suitable for use in potentially explosive areas of Zone 1/2 (gases, vapours, mist) as well as Zone 21/22 (dusts).

The EX PAS (equipotential busbar for potentially explosive areas) offers the following advantages:

• Free of ignition sparks

• Tested by independent testing body up to 75 kA

• Explosion groups IIC, IIB and IIA