Question 1 

 Why does a good earthing system need a uni-potential / equi-potential platform to work well?

Earthing is about safety. During a lightning or fault event, potentials will develop between disparate earthing systems, injury and equipment damage can then result in this scenario. For safety of personnel, plant, and equipment, a uni-potential earth platform must be established where all equipment or systems meant to be at earth potential, are solidly tied together.

Question 2 

What is a clean earth?

This is a misnomer, there is no such thing as a clean earth. Clean earths are sometimes requested by electronic equipment suppliers. This is typically a result of interference on the mains earthing system causing electronic equipment malfunction. What the equipment actually needs is a dedicated (insulated) earth cable from the main earth bar, ideally via an earth electrode system.

Question 3 

Why would I need a surge suppressor earthing system?

Surge Suppressors are high speed shunt devices, designed to operate at high frequencies with high currents. A Surge Suppression earthing system must offer a low impedance at high frequencies and be in close proximity to the TVSS units. A long cable run back to the main earthing system has a high cumulative impedance and inductance, which serves to limit efficient TVSS operation. This earthing system must be at the same potential as the mains earth and offer multiple paths into the body of the earth.

Question 4

How can I protect the equipment inside the building with a lightning protection system?

Use a Faraday cage system i.e. inter connected lightning protection earthing system and air terminal arrangement to ensure that the equipment inside the building is protected. Note the lightning protection system must be at the same potential as the mains earthing system.

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Technical & Engineering Installation of Earthing and Lightning Protection Systems