PRACTICAL:-6
AIM: TO IDENTIFY
DIFFERENT TYPES OF DOMESTIC WIRING.
THEORY:
There
are four types of wiring used in domestic wiring.
(1)Cleat
wiring
(2)
Batten Wiring
(3)
Casing-Capping Wiring
(4)
Conduit wiring
DOMESTIC WIRING:
(1)CLEAT WIRING:
Cleat is in two parts. Two or three grooves are
provided in the bottom part. Cleats are made from China Clay material. There is
one hole in each part to allow the screw to pass through. Wires are placed in
grooves and after putting the top cleat, it is fitted on wall. Distance of half
a metre is kept between the adjacent cleats. Vulcanized India rubber (VIR) wire
is used in cleat wiring. This type of wiring is used only for temporary use. It
cannot be used for permanent use. Wires are in the open atmosphere so there is
effect of dust, moisture, fumes etc.
(2)BATTEN WIRING:
In this type of wiring a long wooden batten is
fitted on the wall with the help of screws. Small clips are fitted on the
batten with the help of small nails. Wires are fitted on the batten with the
help of clips. The type of wiring depends upon the type of wire used.
(a)PVC Wiring:
In this type of wiring PVC wires are used. Single
PVC or double PVC wires are used. PVC wires on batten wiring are popular for
house wiring.
(b) TRS/CTS wiring:
In this type of wiring Tough Rubber Sheath (TRS) or
Cab Tire Sheath (CTS) wires are employed. It is fitted on the batten with help
of clips. As special type of rubber is used instead of ordinary rubber there is
no effect of moisture. This type of wiring is costlier than PVC wiring.
(c) Lead Sheath wiring:
In this type of wiring lead sheath wire is used. So
there is no effect of moisture, fumes etc. Moreover mechanical protection is
available. It is necessary to earth the lead sheath.
(3) CASING-CAPPING WIRING:
There are two types of casing- capping wiring: (A)Wood
casing-capping wiring and (B) PVC Casing-capping wiring
(a) Wood casing-capping wiring:
In this type of wiring there is long strip of wood
with two grooves along the length. This is called casing. Casing is fitted on the
wall with the help of screws. VIR wires are kept in the grooves. Casing is
covered by thin strip of wood. It is known as capping. In this type wiring
there is protection against moisture, dust, mechanical damage etc. but there is
no protection against fire.
(b) PVC Casing-Capping wiring:
Recently PVC Casing-capping type wiring is becoming
popular. It is called PVC Channel wiring also. PVC Channel is in two parts. One
is the base and the other is the top. Base is of C section. Holes are drilled
at regular intervals in the base for fixing. Channel is fixed on the wall or
ceiling with the help of screws passing through these holes. There is snap on
cover which is fixed on channel by pressing it. No nail or screw is needed for
this. Channels are of two types: continuously slotted type and rigid type.
In Continuously slotted type channel,
slots are given on both the side walls. Wires are taken in and out of the
channel through these slots. In rigid type channel no slots are provided.
This type of wiring is light in weight
and can be easily installed. Wires are not to be pulled as in conduit wiring.
Its cost is less and fault can be detected easily, as the channel can be opened
easily. In addition to this the appearance of wiring is also good.
(4) CONDUIT WIRING:
In this type of wiring long thin hollow tube of
steel or PVC called Conduit is used. Conduit is fixed on wall with the help of
saddle. Inspection boxes are provided at certain intervals.
PVC or VIR wire is kept in
conduit. In conduit wiring there is protection against moisture, dust,
mechanical damage, fire etc. however in PVC Conduit wiring there is no
protection against fire.
Types
of conduit wiring:
Conduit wiring can be done by
two ways: (i) surface conduit wiring and (ii) concealed conduit wiring, in
surface conduit wiring conduit is fixed on the surface of the wall or ceiling
with the help of saddle. While in concealed conduit wiring Conduit is kept
under the ceiling or wall. So conduit is not visible. So the appearance of the
room is not spoiled due to the wiring. It is necessary first to decide
precisely the locations of points because it is very difficult and costly to
alter the locations afterwards. Surface conduit wiring are shown in figure.
TYPES OF CONDUIT:
For wiring the following type of conduits are used:
(1)Rigid
steel conduit
(2)
Rigid non-metallic conduit
(3)
Flexible steel conduit
(4)
Flexible non-metallic conduit
1) RIGID STEEL CONDUIT:
This type of conduit is made up of steel. There are
two types:
(a)Heavy gauge screw type
Heavy gauge conduit is either solid
drawn or welded type. Solid drawn conduit is costly. It is used only for gas
proof or explosion proof wiring installations. While seam welded type heavy
guage conduit is used for domestic, commercial and industrial wiring
installations.
(b) Light gauge.
Light gauge conduit is manufactured by bending the
thin sheet of steel. The vertical joint is sometime open. So it is not useful
for weather proof wiring installations. This type of conduit cannot be used as
earth conductor, but separate earth wire should be run.
2) NON-METALLIC CONDUIT:
Non-metallic conduit is made of fiber asbestos, PVC,
high density polythene (HDP) or poly vinyl (PV). PVC conduits are widely used
as it gives protection against moisture and chemical surroundings. Its weight
is less and is less costly and can be installed easily. This type of conduit
can be buried in wall or ceiling.
3) FLEXIBLE CONDUIT:
Where there are vibrations of the machine and where
there is no possibility of installing rigid conduit. This type of conduit is
used. Earthing wire has to be run.
CONCLUSION
