How can the noise from a power earthing system be isolated from a communications network?

While there needs to be a common earthing network and earthing electrode grid, the earthing buses within the system can still separate power earth from communication/signalling earth.

In an earthing system, there needs to be a single earthing grid or network that bonds the earthing electrodes and the main earthing structure within a facility. Some national codes require this single earthing grid or network. There can be various earthing buses that attach to this network to allow for the separation of power earths and communications/signalling earths. In some cases, different 'zones' can be created for the power systems and the communications/signalling systems.

IEC 61000-5-2 provides a great deal of information regarding earthing networks and their implementation. Some excerpts from this standard and additional notes are in the attached document for a brief summary of the basic concepts.

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