E&C-elearn.pdf

ESTIMATING AND COSTING
OF DOMESTIC INSTALLATION
BASIC CONCEPTS AND IE
RULES

DOMESTIC INSTALLATIONS
Electrical installations is used for both
Industrial and non industrial buildings.
(a) Electrical networks in industrial buildings serve the
purpose of distributing the required power to the
consuming points where it is used for multitude of
purposes in the industry.
(b) Non industrial buildings include domestic dwellings
,office,buildings,
shopping and commercial centres institutions, medical
establishments, hotels and sports buildings etc.

WIRING ACCESSORIES
• Fuse (Re-wirable fuse, MCB, etc)
• Sockets & switches
• Weatherproof cables
• Ceiling rose
• Ceiling plate
• Pendant holder
• Earthing thimbles
• Combination switch plates
• Junction boxes
• Hand tools
• PVC casing & caping
• Fasteners
• Distribution board
• Protective devices like ELCB , Main switch , MCB etc

MAIN SWITCH
• MAIN SWITCH – It is a control equipment
which connect or disconnect the main supply. A
iron clad main switch which operate phase &
neutral simultaneously has a fuse and a neutral
link. For single phase DPIC(Double pole iron
clad) main switch with fuse and neutral link is
used. For three phase TPIC(Triple pole iron clad)
main switch with three fuse and neutral link is
used.The rating for main switch for single phase
supply is 5A, 10A, 15A, 30A upto 250 V. For three
phase ratings are 30A, 60A, 100A, 200A, 300A
upto 500V. The thick wire is used for the neutral
link. The main switch rating is calculated by
multiplying the full load current of a subcircuit
by 1.5

DISTRIBUTION BOARD
• It is used to distribute the supply from the
main circuit into various circuit & sub-
circuits .

Selection of wire
• Minimum size of cable or insulated wire for
mechanical reasons.
• Voltage drop
• Current carrying capacity
• Type of insulation used i.e. VIR, PVC, TRS etc.
• Grade i.e. 250 volts, 500 volts, 660 volts grade
etc.

Electrical wiring code
• PVC insulated Aluminium conductor wire
(a) OF size 1.5mm^2 or 1/1.40mm diameter
used for wiring light/fan/5amp. socket points.
(b) OF size 4mm^2 or 1/2.24mm diameter
used to wire 15 amp socket points.
(c) OF size 6mm^2 or 1/2.80 diameter used to wire
15 amp socket points to be used for geysers
,electric oven or other heavy loads.

SEQUENCE TO BE CARRIED
OUT FOR ESTIMATE.
• Drawing the installation plan.
• Calculation 0f total load in Amp.
• Selection and rating of main switch & sub main switch
• Selection & rating of main distribution board .
• Calculation for the length of conduit pipe.
• Calculation for the length of phase and neutral wire.
• Calculation for the length of earth wire.
• Preparing the material table.

CALCULATION OF LOAD
• Tube point - 1x40 = 40 watt
• Lamp point – 1x100 = 100 watt
• Fan point - 1x 60 = 60 watt
• 5 amp socket – 1x100= 100 watt
Total load in amperes = 300/230 = 1.3 A
Selection of main switch – Here a D.P.I.C Main switch of 5.Amp
Rating 250 volt grade is selected.

ASSUME
• Total height from floor to ceiling = 3.5 mt.
• Height of horizontal run from floor = 3.0 mt.
• Height of switch board from floor = 1.5 mt.
• Light and tube points from ceiling = 0.5 mt.
• HR = Horizontal run i.e conduit running parallel to floor
half metre below ceiling.
• VR= Vertical run i.e wires or conduit running between
switch board and HR.

CALCULATION FOR LENGTH OF
CONDUIT PIPE OF 20mm diameter
• From SB to HR = 1.5 mt.
• From entry of circuit into room i.e along H.R upto middle
of room = 2.0 + 0.5 = 2.5 mt.
• From H.R to Lamp point = 0.5(Rise) + 4.0 + 0.5(drop)
= 5.0 mt.
• From fan to tube point = 2.5 + 0.5(drop) = 3.0 mt.
• Total length of conduit pipe = 12mts.
• Taking 10% wastage = 1.2 mt.
• Total length of conduit pipe required for wiring the room
= 13.2 mt. say 13.0 mt.

CALCULATIONS FOR LENGTH OF
PHASE WIRE
• From point of entry of circuit into room upto SB = 2.0(H.R) +
1.5 (H.R) = 3.5 mt.
• From SB upto fan = 1.5(V.R) + 0.5(H.R) + 0.5(rise) + 2.0
along ceiling upto fan = 4.5 mt.
• From SB to lamp = 4.5 mt (upto fan) + 2.0 + 0.5(drop)
= 7.0 mt.
• From SB to tube point = 4.5 upto fan + 2.5 upto ceiling +
0.5(drop) = 7.5 mt.
• Total length of phase wire = 22.5 mts.

NEUTRAL WIRE
• From point of entry of circuit into room upto switch board
= 2.0 along H.R + 1.5(V.R) = 3.5 mt.
• From SB to fan = 1.5 + 0.5 + 0.5(rise) + 2.0 along ceiling
= 4.5 mt.
• From fan to lamp point = 2.0(along ceiling) + 0.5(drop)
= 2.5 mt.
• From fan to tube point = 2.5 + 0.5 (upto tube point)
= 3.0 mt.
• Total length of neutral wire = 13.5 mts.

TOTAL LENGTH OF WIRE
• Total length of wire required for wiring the room
(phase + neutral) = 22.5 mt. + 13.5 mt. = 36 mts.
• Allowing 15% extra for wastage and connections
= 5.4 mt
• Total wire required for wiring the room = 36.0 +
5.4 = 41.4 mts. say 41 mts.

EARTH WIRE
• The earth terminal of the socket outlet is solidly
connected to the switch board with a 14 SWG,
earth wire through an earthing thimble.
• Earth wire of 14 SWG (Say 0.25 mt) will serve the
purpose.

LIST OF MATERIALS
• Conduit pipe 20mm dia. Qty -13 mt.
• PVC insulated, aluminium conductor, single core 250 volt
grade of size 1.5mm^2 or 1/1.40 mm dia. Qty- 41mt.
• Earth wire 14 S.W.G GI. Qty - 0.25 mt.
• Iron clad, concealed type, switch boards, with bakelite
sheets 20cm x 25cm. Qty – 1 No.
• Conduit pipe accessories for 20mm dia conduit
1 way junction box. Qty - 2 Nos.
2 way junction box. Qty – 1 No.
3 way junction box. Qty – 2 Nos.
Conduit bends. Qty – 3 Nos.
Conduit nuts hexagonal to fix conduit with SB . Qty – 8
Nos.
Conduit sockets to connect two pieces of conduit. Qty –
8Nos.

LIST OF MATERIALS
• Switch, 5 amp rating. Qty – 4 Nos.
• Socket , 5 amp rating . Qty – 1 No.
• Ceiling roses, 2 – plate, bakelte. Qty – 2 Nos.
• Junction box covers. Qty – 2 N0s.
• Lamp brass bracket with holder. Qty – 1 No.
• Earthing thimbles. Qty – 1 No.
• Hexagonal headed bolt and nut 6 mm dia. 25mm long
for fixing earthing thimbles with switch board
Qty- 1 No.
• Labour charges @ 20.00 per point for 4 points
• Miscellaneous expenses @ 10% of total cost.
(including supervision charges)
Apply the suitable rates for the materials and
the calculate the -
• Total cost of wiring Rs________

WHAT IS ESTIMATING?
ESTIMATING is an art of assessment of quantities of
different items and costs thereof to plan the amount
required for executing a work before carrying out the
work.

PURPOSE OF ESTIMATING
 MONEY - To determine necessary amount of money required
by the owner to complete the proposed work.
 QUANTITY – To determine the quantities of materials require
d in order to program their timely procurement.
 WORKER – To determine the number of various types of wor
kers required in each work.
 TOOLS AND PLANTS – To arrange necessary tools and plan
ts as per schedule of work in correct numbers.
 SCHEDULE – To create a schedule of work.
 TIME - To calculate the completion time of project.

POINTS TO REMEMBER:
 Complete specifications of materials.
 Complete schedule of the points to be wired for with
their switches and fittings.
 Plans and selections marked with details, at least wit
h the position of main switchgear and distribution
board. Other information about factors affecting the
cost of an estimate.

WHAT IS INDUSTRIAL INSTALLATION?
 Industrial installation means an installation int
ended for use in the manufacture or processi
ng of products involving systematic labor or h
abitual employment and includes installations
in which agricultural or other products are ha
bitually or customarily processed or stored fo
r others, either by buying or reselling on a fee
basis.

IMPORTANT CONSIDERATIONS REGARDING
MOTOR INSTALLATION WIRING.
 Equipments should be of iron clad construction and wiring shall
be of armoure cable or conduit type.
 Woodwork shall not be used for mounting of switchgear.
 The length of conduit between terminal bases of motor and sta
rter, switches and motor shall not exceed 1.25 Mtrs.
 Looping of conductors and use of joints shall not be done.
 Every motor shall be provided with separate switch fuse placed
near it.
 All motors should be provided with suitable starters.
 The conduit should preferably be laid in covered trenches.
 Laying of cables must be in separate conduits for separate mot
ors.

CONSIDERATIONS CONTINUED:
 Minimum cross section of aluminum conductor : 2.5 mm2 and minim
um cross section of copper conductor : 1.25 mm2.
 The current rating of the cables for supply to motor may be based on
normal full load current of the motor but fuse rating should be based
on starting current.
 Conduit used shall be electrically continuous throughout and connec
ted to frame of motor.
 Wire used to earthing conductor shall be of copper or galvanized iro
n.
 Consumer is required to provide his own earthing system with and in
dependent electrode.
 While dividing the current rating of main switch controlling a group of
motors, starting current of one motor plus full load current of remaini
ng motor shall be considered.

QUESTION
 A 3 phase induction motor of rating 5HP
, 50 Hz, 415 V is to be installed in a roo
m of size 5m x 3m x 3.5m high. The mo
tor should be one meter away from the
nearest walls. Prepare the list of materi
als and estimate their cost. Also, draw t
he installation plan, single line diagram
and wiring diagram.

ANSWER
 Assumptions:
1. 1. Height of main distribution board (MCD) from floor level = 1
.5 m.
2. 2. The motor installed on a foundation 0.25 m above floor leve
l.
3. 3. Two number earth wires enclosed in G.I pipe are installed s
ide by side for earthing the motor.
4. 4. Height of horizontal run of conduit pipe below ceiling is 0.5
m.

Selection of TPIC main switch.
The full load current is 8 amperes. Assuming 50% overload i.e.
8x1.5=12.0 amperes the standard size of kit-kat fuse available in the
market is 16 amp. Since 16 amperes is very close to the value of
12 amperes the next higher standard size of kit-kat fuse i.e.
32 amperes is selected. So, TPIC main switch of rating 500V,
32 amperes will be used.

Selection of size 3 core cable.
PVC cable of size 3 core 4 mm2 , 1/ 2.24 mm 660V, will
be used which has a current rating of 14 amperes that is
more than 12 amps.

• Calculation of length of HEAVY GAUGE conduit pipe,
15 mm Diameter.
From main distribution board (MBD) to motor foundation
=1.5+3+1.5+1.5+0.2+0.5+0.2+0.25 = 8.65 mtrs.
10% wastage = 0.86 mtrs.
Total length of conduit required = 9.51 say 10 mtrs.

• Calcluation for length of HEAVY BOARD gauge conduit
pipe 15 mm Diameter, for earth wire.
From main distribution board (MBD) to top of motor foundation
(Total length of 15mm conduit required) x 2 = 10 x 2 = 20 mtrs.

• Calculation for 3 core PVC cable of size 4mm2
From 3 φ energy meter to MBD = 1.5 + 3 + 1.5 = 6 meters.
From MBD to 3 φ induction motor= 1.5+0.2+0.5+0.2+0.25
=2.6 meters.
Total = 8.65 meters.
10% wastage = 0.865 meters.
Total length = 9.51 say 10 meters.

• Calculation for length of 8 SWG GI Earth wire
From MDB to 3φ induction motor = (1.5+0.2+0.5+0.2+0.25)x2
= 2.65 x 2
= 5.30 meters.
10% wastage = 0.53 meters
Total length = 5.83 or say 6 meters.

LIST OF MATERIALS
S. No. Specification of material Qty. Rate Amount
1. TPIC, main switch, 16 amps rating, 500V
grade
1 No. 700 700.00
2. Heavy gauge conduit pipe, black enamel 15
mm diameter
Conduit accessories : conduit bends
Conduit saddles to hold conduit with wall
30mts
2 Nos.
4 Nos.
30/mts
20/each
40/doz.
900.00
40.00
4.00
3. Flexible conduit 15 mm diameter 1 m. 30/mts. 30.00
4. Flexible conduit coupler to connect rigid
conduit and flexible conduit together
2 Nos. 20/each 40.00
5. Flexible conduit attachment with locks nuts
to attach flexible conduit with main switch,
starter, motor etc
6 Nos. 5/each 30.00
`
6. PVC insulated, aluminum conductor, 3 core,
4mm2 or 1/ 2.24mm diameter, 660 volt
grade wire
10mts 150/mt. 1500.00

S.
No.
Specification of material Qty. Rate Amount
8. Earthing thimbles 16 amp rating with
nuts and
bolts to connect earth wire with
components
10
Nos.
5/each 50.00
9. Iron clad board fabricated with angle
iron and MS sheet of size 30cm x 45cm
1
Nos.
180/eac
h
180.00
10. A> Rag bolt of dia 12mm and 20cm long
with nut
For holding iron clad board with wall
B> Bolts with nut 10mm dia 30mm long,
for fixing main switch and starter with
MB
4
Nos.
8
Nos.
10/each
1/each
40.00
8.00
11. Teak wood guttis (plugs) for fixing
conduit saddles with wall
30
Nos.
2/each 60.00
12. Wood screws, 25mm long for fixing
saddles with wall
30
Nos.
1/each 30.00
13. Caution plate (danger 440 volts) 1 No. 50 50.00

S.
No.
Specification of material Qty. Rate Amoun
t
15. Civil engineering works such as grouting of
Rag bolts for fixing main board and motor
Control board, making motor foundation,
Concrete pit, cover for pit etc. =1 ½ bag
cement
500.00
16. Labour charges for civil engg. Works - - 300.00
17. Transport of wiring material to work site.
Contingencies @5% of total wiring cost.
Total cost involved in power wiring.
-
-
-
-
100.00
4912.0
0
245.00
5157.0
0
18. Earthing set 2 Nos. complete as under
assuming depth of earth electrode to be 7
meters using
plate earthing system:
1. G.I earth plate 60cmx60cmx6.36cm
2 Nos.
24
150/eac
h
300.00
600.00

S.
No.
Specification of material Qty. Rate Amoun
t
3. G.I pipe 20mm dia for watering i.e. from
funnel to earth plate
4. 8 SWG GI earth wire from main board to
earth plate
5. Cast iron frame 30cmx30cm for both
sets
6.Cast iron frame 30cmx30cm for both sets
7. Funnel with wire mesh
8. G.I bolts 10mm dia, 25mm long with
nuts
9. Earthing thimbles 60 amps rating to
connect earth wire with earth plate
10. Charcoal 15 kg for each set
11. Salt 20 kg for each set
12. G.I pipe bends for 15mm dia pipe
13. Soldering material for soldering earth
wire with thimble
14. Cement, sand, concrete
15. Labour for earthing
16. Expenditure on transportation of
10
mts
6 mts
2 Nos.
2 Nos.
2 Nos.
4 Nos.
2 Nos.
30 kg
40 kg
6 Nos.
-
-
-
-
-
25/mt
50/mt
50/each
20/each
15/each
2/each
6/each
4/kg
2/kg
10/each
20/each
-
-
-
-
-
250.00
300.00
100.00
40.00
30.00
8.00
12.00
120.00
80.00
60.00
40.00
500.00
300.00
100.00
2840.0
0

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