Why is steel wire armour (SWA) not used as the protective conductor in agricultural cable installations?

Why is steel wire armour (SWA) not used as the protective conductor in agricultural cable installations?

• A. Because a core within the cable should be used for this purpose
• B. Because SWA is banned in agriculture
• C. Because SWA has insufficient mechanical strength
• D. Because SWA increases corrosion risk

Answer: (A)

Protective conductors need a reliable, continuous earth path that is specifically designed to carry fault current. Steel wire armour is there mainly to protect the insulated cores from mechanical damage; it isn’t guaranteed to remain continuous or properly bonded under all operating conditions in agricultural environments. If the armour were used as the earth path, damage, corrosion, or joint failures could break the fault-current return path and leave equipment unearth ed, posing a shock risk. A dedicated, insulated core inside the cable provides the required continuity, insulation, and bonding, so the protective conductor is designed for that purpose. That’s why a core within the cable is used for the protective conductor rather than the SWA.

Protective conductors need a reliable, continuous earth path that is specifically designed to carry fault current. Steel wire armour is there mainly to protect the insulated cores from mechanical damage; it isn’t guaranteed to remain continuous or properly bonded under all operating conditions in agricultural environments. If the armour were used as the earth path, damage, corrosion, or joint failures could break the fault-current return path and leave equipment unearth ed, posing a shock risk. A dedicated, insulated core inside the cable provides the required continuity, insulation, and bonding, so the protective conductor is designed for that purpose. That’s why a core within the cable is used for the protective conductor rather than the SWA.