[=Connection of negative wires, pipe lines and track. Bonding of
track.=] The bonded track, the negative wires and metallic pipe
lines, when coming near each other, may be connected together at
intervals not exceeding five hundred feet, and any track used as the
return or earth system shall be properly bonded. In no case shall a
pipe line, or any part thereof, be used exclusively as the return,
and when connected to the earth system, the negative wire or bonded
track shall be of ample capacity, exclusive of the pipe line, to
carry the current.


[=Trolley wires; how erected.=] The trolley wire shall be carried
upon hangers or other fixtures which will properly insulate it from
contact with the roof or other substances, and so the trolley wheel
can trail without the necessity of being constantly attended for
that purpose, and no trolley shall be run on any wire not so
carried.


[=Locomotive must not be operated improperly.=] No locomotive shall
be operated by means of a person holding and sliding upon or
frequently making contact with the positive wire with any device
attached to the cable as a substitute for a trolley, but these
provisions shall not prohibit the operation of a locomotive by means
of a cable without the use of the trolley, provided the cable be
connected to and disconnected from the positive wire when the
locomotive is not in motion.