Page 239 - Electrician - TT (Volume 2)

ELECTRICIAN - CITS

Different colour may be used to aid identification of group of controls and functions.
The associated earth and neutral conductor should be routed close to the respective live conductors to avoid
undue loop resistance.

Select the race ways to leave some slacks or looping of the cable inside it. The wires inside the race way should
not more than the half fill.
Bunching and tying
Run the wires in horizontal and vertical lines avoid diagonal runs as possible. Do not run the wire over the
other devices or race ways. Uses of spring cage terminals instead of standard screw terminals can reduce the
termination error, the wiring and maintenance time which in turn reduce the cost and labour.

To connect the accessories, cut the individual control wires to the proper lengths, strips the insulation, mark wire
identification, insert ferrules at the ends of wires, use suitable lugs or thimbles.
The wires should be neatly bundled, run in the race ways and routed with smooth radius bends.
All the terminals, wires and components should have identification marks and labels. A good labelling and
identification will reduce the errors in termination, testing, maintenance and repairs. A legible and durable label in
an efficient and cost effective manner may be chosen.
To the possible extent the power and control wiring should be run in separate race way or cable management
which will reduce the radio interference, trouble shooting time and make the future alteration if any is easier.

By taking some extra cares like pest control, dust control, adequate terminal pressure, selection of proper wires
and accessories, it can be ensured that the control panel has no failure time and with moderate maintenance it
will be trouble free panel for entire life.

Where the multiple earths are used it is necessary to use a common earth terminal or connectors as in Fig 5.
Tests
Before energizing the control panel all necessary tests should be carried out like open, short, earth continuity and
earth soundness etc. The supply voltage and frequency are also to be checked.
Control elements
Difference between control panel and switch board
A panel board contains a single panel or a group of panel units as single panel that includes bus-bars, protective
devices and control switches, instruments and more starters etc.
For wiring of control panel board the following control elements / components and accessories are required.
They are
- Isolating switch

- Push button switch
- Indicating lamp
- MCB (Miniature Circuit Breaker)
- Contactors
- Electro mechanical relays

- Thermal over load relays
- Time delay relay (timers)
- Rectifiers
- Limit switches
- Control transformers etc.

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CITS : Power - Electrician & Wireman - Lesson 93-100 CITS : Power - Electrician & Wireman - Lesson 93-100