Regular Electric Wiring Inspection and Installation of Substation

A distribution system can include substations, main feeders, sub feeders, panel branch circuits, and a variety of switch-gear and fusing devices. Main feeders, sub feeders branch circuits are two or more wires enclosed in a protective covering and conduit.

Wiring systems should be checked frequently to reduce fire hazards, correct defective wiring, and eliminate oversized lamps and overloaded circuits.

A Regular Wiring Inspection Should:

i. Improves conditions or eliminate wiring from locations that are dirty, poorly ventilated, moist, or subject to chemical fumes:

ii. Eliminate improper or unauthorized connections;

iii. Repair damaged wiring devices, defective insulators, broken parts, or exposed live parts:

iv. Eliminate excessive cable sag and vibration;

v. Eliminate crowded cable spacing and conduits or raceways;

vi. Look for evidence of overheating, grounds, and short circuits;

vii. Protect non-current-carrying parts from corrosion with paint or other material; and

viii. Eliminate unsafe, unreliable, cable and wire to power panels.

Installation of Substation:

1. Fire extinguishers suitable for electricity must be installed in sub-station/switch station.

2 Every frame of transformer/switch gears and any other used for regulating or controlling energy at medium high or extra high voltage must be doubly earthed.

Fuses protect the wiring system and electrical equipment from short circuit and overloads. The ampere rating of the circuit and its fuse must be consistent. Periodically, fuses should be inspected to determine whether

i. Breaks, cracks, or burns exist in the insulator:

ii. Contact surfaces of the fuse are pitted, burned, or misaligned

iii. The fuse holder is corroded or dirty; and

iv. The bolts, nuts, washers, pins, and terminal connectors of a fused circuit are in place and in good condition.

Although a circuit breaker functions like a fuse, it can be repaired, if a circuit breaker open due to an overload, only a reset is necessary. It a circuit breaker fails to open when required, however, serious damage can result. Regu­lar inspections of the circuit breaker should look for

i. An oil gauge reading,

ii. Breaker tank oil levels,

iii. Oil or air leaks,

iv. Broken porcelain,

v. Loose-hardware,

vi. Broken or missing cotter pins,

vii. Air-supply compressor,

viii. Deenergized cabinet heaters,

ix. Excessive corrosion or rust,

x. Loose gasketed covers, and

xi. Unusual noise, smoke, or temperature.

Distribution panels and cabinets should be inspected for signs of rust, dirt, oil, debris, moisture, loose connections, and unauthorized or nonstandard attach­ments. Disconnecting devices contained in the cabinets should be labeled to indicate circuit or feeder designation, and the unit should be labeled to show all current and voltage characteristics.

To prevent tampering, cabinets should be locked. Because moisture and humid conditions can create problems, large cabi­nets may require strip heaters to maintain a temperature that inhibits condensation when the equipment is not operating.

Dangerous conditions may develop if the switch-gear is totally neglected. Periodic inspection is necessary; the fault may not become apparent as in the case of rotating machinery. Periodic inspection and cleaning of switch boards panels etc. is made to prevent the deposition of dust. A good wax polish is rec­ommended for this purpose.

A detailed program should be drawn-up for the proper maintenance of switch-gears and switchboard installation –

(i) For the frequently operating gears the inspection period should be between one to three months.

(ii) For the infrequently operating gears yearly inspection period is sufficient.

(iii) If any switch-gear is left close for more than six months without any operation, it should therefore be operated (open-and-closed) for few times to ensure that it is in perfect working order.