Directional ground fault protection

Contacts with other pipelines or grounds can be localized to within a few hundred meters by pipe current measurements. Contacts with foreign pipelines or cables can also be found by measuring potential at the fittings of the other line while the protection current of the cathodically protected pipeline is switched on and off. While the potential of unconnected pipelines will assume more positive values when the protection current is switched on, the cathodic current may also enter any line in contact with the cathodically protected pipeline and thus shift its potential to more negative values. Should the contacting line not be located by this method, fault location can be attempted with direct or alternating current. 

Insulation separates live parts of the product from the user and prevents live parts from coming into contact with each other. For protection against direct and indirect contact with live parts insulation is safer than grounding or fusing. The protective measures are shown in the relative product standards and apply to all products and machines. The types of insulation applied between circuits of different potentials and metal parts depend on the equipment class, possible faults, and the parts in question. The voltage and part or circuit accessibility are also important for proper selection of the insulation type, such as double or reinforced insulation between live parts and user-accessible parts. Basic insulation is required between live parts and grounded metal parts. 

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