Observation

(a)       (i)   Open circuit: This type of fault occurs as a result of failure of one or more  
conductors e.g. fuse in an electrical circuit leading to extremely high resistance value and zero current flow in the circuit.  OR when the conductor breaks cut
OR when there is discontinuity.                                                                                                
(ii)  Short circuit:  This type of fault occurs when contact is made between two wires  
of different polarity (live and neutral) thereby leading to the flow of excessive current in the circuit.                                                                                                                     

1.  Earth leakage: Is the unwanted flow of electrical current from live wire to the

 earth.  Earth leakage in an uncontrolled amount can lead to rise in current, damaging conducting paths and causing electric shock.                                              

(b)       (i)   Advantages of all – insulated and sheathed surface wiring system

                    -   simple and easy to install.
-   faults are easily detectable
-   easy to customize (alteration and addition)
-   suitable for temporal use.
-   easy inspection.
-   prevents electric shock

           (ii)     Disadvantages of all – insulated and sheathed surface wiring system

                    -   sag may occur after sometimes
-   It has poor (duty) appearance
-   The risk of fire outbreak is high
-   since cables are in open air, they can be affected by smoke, humidity and acidic   
effect to cause damage to the cables.
Most candidates who attempted this question did not do so well. They could not
explain the terms well and failed to give the required advantages and disadvantages.