Potential equalization

Protective equipotential bonding (SPA)

Protective equipotential bonding, also known as main equipotential bonding, creates an electrically conductive connection that brings the bodies of equipment and other conductive parts to the same potential. This limits voltage differences and prevents them from occurring in the first place, even in the event of a fault such as an earth fault or short circuit.

In the interior of a building, all extensive metal installations must be electrically connected to each other and routed to the earth electrode. This means that these parts have the same potential. If individual parts are touched, there is no voltage difference that could endanger people or objects. At most, a potential difference could still exist to the earth electrode or conductors connected to it (e.g. neutral earth conductor, protective earth conductor). To avoid this too, the equipotential bonding conductor must be connected to these system parts so that all conductive parts within a building have the same potential.

Parts to be connected to the main equipotential bonding:

• Water, gas, heating and ventilation pipes
• Lift rails
• Supporting metal structures
• Expanded metal parts of building structures
• Metal chimneys or metal insert pipes
• Cable sheaths
• Main earthing conductor, main earthing busbar
• PEN conductor of the connecting cable
• Main protective earth conductor (PE)
• External lightning protection system