With reference to a three phase shipboard electrical distribution system:

(a) Enumerate the advantages of an insulated neutral system (4)

(b) Enumerate the disadvantages of an insulated neutral system (4)

(c) State why an Earthed neutral system may be earthed through a resistor (4)

(d) Compare the use of an insulated neutral system as opposed to the use of an Earthed neutral system with regard to the risk of electric shock from either system (4)