wiring and earthingAFAFAFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF

DFW

1. Types of wires

2. Wires and cables
•Conductor and insulator
Electricity can flow easily through conductor
Copper and aluminium
Insulators offer a very high resistance to the
flow of electricity
The type of wire depends upon the type of
insulation used. Generally rubber and PVC
are used as insulation on wires

3. Types of wires
•V.I.R. wires
–Vulcanised Indian rubber wires-used in cleat
casing, capping and conduit wiring.The
conductor is insulated with indian rubber and
vulcanised
•C.T.S./ T.R.S. wires-
Tough rubber sheathed or Cab tyre sheathed
wires- over the insulation of conductor tough
rubber sheath is provided for additional
insulation and protection against wear and tear.

4. Types of wires
•P.V.C. wires
Conductors are insulated with PVC-used in
cleat casing, capping and conduit wiring.
The use of these wires is avoided in for
giving connection to heating apliances.

5. Cables
•Cables means any current carrying conductor
either solid or stranded section provided with
overall insulation.
•The cables may be constituted of one or more
than one conductor section called ‘cores’.
•Each core conductor is insulated individually and
all cores are enclosed i.e. bunched together in
one common mechanical protective covering or
sheath.
•Cables can be used as Aerial cable or
underground cables

7. Armoured Cables
•Conductor –one core in the centre and
number of cores of stranded (aluminium or
copper conductor)
•Insulation over cores
•Metallic sheath
•Bedding
•Armour

8. Armoured cable

9. Size of a wire
•The current cattying capacity of a
conductor is limited. When current flows
through a conductor, it gets heated. There
is a limit to the amount of heat which a
particular size of conductor and type of
insulator can withstand safely.
•The size of wire is selected depending the
amount of current it is expected to carry.

10. Standard wire gauge

11. Size of wires
•S.W.G.
Standard wire gauge
1/18 single core wire of 18 gauge.
Now described 1/0.048 inch or 1/ 1.2192 it is
1.1675 sq mm
37/16- 37/0.064 – 37/1.6256
16 gauge is 2.0755 sq mm wire.
Current rating is maximum current carrying
capacity of a wire.

14. Types of wiring

15. •Casing and capping
•Cleat wiring
•Conduit wiring – open or concealed
•Metal sheathed wiring
•Cab Tyre sheathed (C.T.S) or tough
rubber sheathed wiring (T.R.S.)
•Wiring by mineral insulated wires.

16. Conduit wiring
• Conduit wiring is the best system of
wiring, there are two methods of laying
conduits.
•Surface wiring
•Concealed wiring.

18. EARTHING
•The main objectives of the earthing are to:
•Provide an alternative path for the fault current to flow so that it will
not endanger the user
•Ensure that all exposed conductive parts do not reach a dangerous
potential
•Maintain the voltage at any part of an electrical system at a known
value so as to prevent over current or excessive voltage on the
appliances or equipment.
The qualities of a good earthing system are:
•Must be of low electrical resistance
•Must be of good corrosion resistance
•Must be able to dissipate high fault current repeatedly

19. G. I. plate or copper plate
earthing-

20. G. I. plate or copper plate
earthing-
•G. I plate- 60cm X60cmX3.18 mm thickness
•Socket is soldered at the end of earthed wire this socket is bolted to
the plate by copper nulls and bolts.
•G. I. pipe of 12.7mm diameter is placed of the top of earthing plate.
Through this pipe the earth wire is drawn. This pipe should be at
least 60 cm below ground.
•Another pipe of 19.05 mm diameter is also placed at top with a
funnel .The top of funnel remains in a chamber 30 cm X 30 cm
X30cm with brick walls and cast iron plate as a cover.

21. Pole Earthing

22. Pole Earthing
•G. I. pipe is used as earth electrode The size depends upon fault
current and condition of soil.
•The length of pipe in soft and moist soil is 2 meter, if the soil is dry it
should be 2.75 m.
•To maintain the contact between inner surface of the pipe and soil-
some holes of 12 mm X are made on the pipe of equal interval.

23. Pole Earthing
•The pipe is placed up right in the pit. It should be placed of a depth
of 4.75 m. below the grand level.
•The pipe of the bottom is surrounded by charcoal or Brocken pieces
coke. For and salt for a distance of 15 cm around the pipe.
•Charcoal increases the contact surface salt decreases the earthing
resistance
•Alternate layers of salt and charcoal are arranged in earth pit.
•To maintain the moist condition of soil for effective earthing,
arrangement should be done for pouring water
•G. F. pipe of 19 mm diameter is connected to top of earth electrode-
with a funnel of top.

24. G. I. plate or copper plate
earthing-
•G. I plate- 60cm X60cmX3.18 mm thickness
•Socket is soldered at the end of earthed wire this socket is bolted to
the plate by copper nulls and bolts.
•G. I. pipe of 12.7mm diameter is placed of the top of earthing plate.
Through this pipe the earth wire is drawn. This pipe should be at
least 60 cm below ground.
•Another pipe of 19.05 mm diameter is also placed at top with a
funnel .The top of funnel remains in a chamber 30 cm X 30 cm
X30cm with brick walls and cast iron plate as a cover.

25. Lightning conductor
•The
 
lightning 
diversion theory
states that a lighting
rod
 
protects a building 
by
providing a conductive
pathway of the charge to the
Earth. ... By diverting the
charge through
the
 
lightning 
protection
system, the
 
building 
is spared
of the damage associated with
a large quantity of electric
charge passing through it.