Question

Propose THREE protection methods to against electric shock for direct contact and THREE protection methods for indirect contact.

Answer 1

Protection methods against electric shock for direct contact: - The methods of preventing direct contact are mainly concerned with making sure that people cannot touch live conductors. These methods include: 1) The insulation of live parts - this is the standard method. The insulated conductory should be further protected by sheathing, conduit ete, 2) The provision of barriers obstacles ori enclosures to prevent touching (1924). Where surfaces are horizontal and accenible, (P44 protection applies .. 3) Placing out of reach of on the provision of obstacles to - prevent people from reaching live parts . 4) The provision of residual current devics CR CDA) provides supplementary protection but only when contact is from a - live part to an earthed part . Protection methods against electric shock for indirect contact: - There are three methods of providing protection from shock after contact with a conductor which would not normally be live : 1) Making sure that when a fault occurs and make the parts - live, it results in the supply being cut off within a top time. In practice, this involves limitation of earth

fault loop impedance , 2) Culling off the supply before a fatal shock can be received during a residual current device 3) Applying local supplementary equipotential bonding which will ensure that the resistance between the parts which can be touched simultaneously is to low that it is imponible for a ongerous potential difference to erist between them. It is important to stress that whilst this course of action will eliminate the danger of cinderect contract, it will still be necessary to provide disconnection of the supply to guard against other fouets, such as over heating