Page 291 - Electrician - TT (Volume 2)

ELECTRICIAN - CITS

Total wattage = 390 + 370 =760W

As this is well within 800w rating of a branch circuit we can wire up the hall and sit out in one branch circuit. draw
the position of the switches, sockets, lamps and fans in the house plan.
The total load is of lighting, fan and three pin sockets amounting to 760w which is less than 5A as such cables
selected is 1mm2 copper cables, or aluminum cable of 1.5 mm2
Horizontal run j -150cm-1.5m
Total of two to five 25m
1 mm2cable required

Conduit run J= (2.5+0.9+0.8) x 2= 8.4m
Conduit run A = (1.5+0.9+0.8) X 7 =22.4m
---do-------- B= 1.1x 2 = 2.2m
---do-------- C= (1.05 x4+1.85X2) = 7.9m
---do-------- D=(1.5+0.8+0.9) X3 =9.6m

---do-------- F =(1.8+0.9+0.8) x 5=17.5m
---do-------- G =2.2---do-------- x2= 4.4m
---do-------- H= (2.2+0.8) x2 =6m
---do-------- K = (0.9+0.2) x 2=2.2m
Total = 80.6m, say 90m of cable required.

Copper wire 14swg for earthing router K, H, F, E, D and A =16.9m say 20m or 600g
Labour charge
Electrician =Rs150, two days = Rs 300/
Helper = Rs 90 two days = Rs180/
Three phase wiring installations

Separate and distinct circuit for lighting, fan, heating and power wiring
All the wiring conductors shall be run at a height of 2.5m along the wall or on ceiling.
Proper distribution of load should be done at the main db. and Brach db.
The load should have arranged as balanced on all the phases in case of three phase four wire system DB should
be located at a convenient point (at the load center)The third pin of all the wall socket must be earthed with
min size of earth conductor of GI ,14swg or 1.4 mm2aluminumAll the metal boards must be double earthed for
medium and high voltage installation. The phase neutral and earth wire shall be distinctly marked.
General instruction about power installations:
1
2 For power circuit, 3000Watts and above.

3 Induction motors of 3HP and above should be of 3phase type.
4 Motors of up to 5HP can be controlled by DOL starters.
5 Induction motors above 5HP are to be started using starters in order to reduce starting current.
6 For internal wiring, VIR / PVC cables of suitable size is to be used in conduit pipes.

7 In factories, power distribution is effected from a suitable location, known as distribution centre, through a
switch board.
8 All power equipments should have Iron clad switches and conduit pipes.

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CITS : Power - Electrician & Wireman - Lesson 104&105