Question

which circuits must not be connected to any system containing trolley wires with a ground return? a. ground wires b. grounding conductors c.circuits for lighting and power d. ungrounded trolley wires

Answer 1

Circuits for lighting and power shall not be connected to any system that contains trolley wires with a ground return.

Because "Lighting and Power Circuit" contains the high voltage electricity phase powers and We know that when phase is directly touched the ground may causes the electrical short circuit or electrical hazards because of ground returns exist in trolley wires.

An example of that, with a grounded frame, an accidental ground in a machine may result in damage if there is an accidental ground or a ground connection in the external circuity while on the contrary, if the frame of the machine were insulated, no damage would occur.

This is said to be particularly the case with railway power-plant machinery feeding energy into a trolley system with ground return, and to a considerable degree, at least, with electrical machinery of all kinds.

* Exception where Circuit for Lighting Power may be permitted:-

- Car House

- Power House

- Passenger and Freight stations operated in connection with electric railways.

Hence option "C" is correct answer.

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