97. Insulation of returns .-(1) Where any rails on which cars run, or any conductors laid between or within 0.9 metre of such rails, from any part of a return, such part may be uninsulated. All other returns or parts of a return, shall be insulated, unless they are of such conductivity as to secure the conditions required by sub-rules (2) and (3) of rule 98.
(2)Where any part of a return is uninsulated, it shall be connected with the negative or neutral of the system.
