Code of Practice for Power Installations, materials required for power circuit wiring and their specifications, Prepare the layout diagram of machines showing clearances as per IS standards, draw wiring plan of the Power circuit for workshops, Decide the type of wiring system, load calculations, determine the size of conductors, main switch, Isolators, sub switches and protective devices, Draw the SLD of Power Distribution Scheme showing grading/discrimination of ratings of protective devices, Prepare the schedule of materials with specifications for workshops and their estimates, Determine the rating of motor for IP set and the concept (only)of pump house wiring.

1. 1
Prepared By:
Mr.Premanand Desai L/EE
B.L.D.E.A’s SHREE SANGANABASAVA
MAHA SWAMIJI POLYTECHNIC,
VIJAYAPUR-03
E-mail ID:ssmp.premananddesai@bldea.org
cell no : +91 7892881829
COURSE & CODE: ELECTRICAL ESTIMATION AND COSTING (15EE54T)
UNIT - 04
POWER INSTALLATIONS

2. 2
COURSE & CODE: ELECTRICAL ESTIMATION AND COSTING (15EE54T)
UNIT - 04
POWER INSTALLATIONS
4.0 Introduction
Power circuit can be divided into two main categories.
1. Power circuits for heaters, coolers, refrigerators, air-conditioners and other similar
load.
2. Power circuits for motors, generators, air-conditioning equipment / ventilation
equipment, machine tools , other special purpose large loads.
4.1 Code of Practice for Power Installations.
1. Power circuit most be drawn in surface conduit system only. Lighting circuit also
done in conduit system itself with sufficient numbers of circuits.
2. The length of Flexible conduit used for connections between the terminal boxesof
motors andstartersswitchesmotorshallnotexceed1.25meters.
3. The conduit should be preferably be laid in covered trenches to facilitate operator
movement (safe).
4. In addition to switch and fuse motors shall be provided with suitable means for
starting and stopping (starters) at suitable places. For Slipring motors resistance
starters along with oil immersed, D.O.L starters are used and in squirrel cage I.M.
up to 3 HP DOL, 5 to 10 HP star-delta semi- automatic and 12 to 25 HP fully
automatic starter are to be used.
5. Suitable size of conductor according to current rating with factor of safety of 2 is to
be calculated.
6. Each machine must be provided with two earthing and the earthing wire should not
looped
7. All metallic parts such as bodies of equipment’s covers of switch gear etc., must be
earthed properly with lugs fixed by nuts and bolts.
8. Penal board and meter board are to be fixed at a height of 1.5 m above the floor.
9. To improve the power factors of Induction motor each motor is provided with
capacitor of 1 RKVA for each 2.5 HP.
10. M.C.B up to 5 KW load and above 5 KW load E.L.C.B and M.C.B is to provided.
11. For connected load above 100 KVA, H.T (11 KV) supply is to be taken.
4.2 Materials required for power circuit wiring with their specifications.
1. Main Switch
a. Two - wire (1-phase AC circuit) – 240V , 16A , D.P.I.C switch with Fuses.
b. Two - Wire (DC circuits) – 500V , 32A /63A/100A/150A etc., D.P.I.C switch with Fuses.
c. Three Phase circuits – 415V , 32A /63A/100A/150A etc., T.P.I.C switch with Fuses.
2. Miniature circuit breaker (M.C.B) - 1Ø /3Ø , 5A/10A/15A/20A/30A/40A etc.,
250V/500V Voltage grade.

3. 3
3. Earth Leakage Circuit Breaker (E.L.C.B) - 1Ø /3Ø , 5A/10A/15A/20A/30A/40A etc.,
250V/500V Voltage grade.
4. Starters - The Choice of a starters depends on the following factors
a. Type of motors used. b. BHP of the motor.
Sl.No. Type of Motors Method of Starting
1. Induction motors of very low rating.(Up to 5HP) Direct Online Starters
2. Induction Motors of Medium rating (Up to 15 Hp) Start – Delta Starters
3. Induction Motors of High rating (Above 15 Hp) Auto Transformer starter
4. Slip ring induction motors of high rating Rotor resistance stater
5. D.C Series motors Two point starters
6. D.C Shunt Motors Three point Starters
7. D.C Compound Motors Four point starters
5. Cable – Copper or Aluminium , In copper – 1 sq.mm, 1.5 sq.mm, 2.5 sq.mm, 4 sq-mm,
6 sq.mm, 10 sq.mm etc., In Aluminium – 4 SWG, 6SWG, 10SWG, 25 SWG, 35 SWG,
50SWG, 95 SWG, 120 SWG, etc., PVC or CTS or VIR insulation , 1.1 KV voltage Grade.
6. Conduit – Rigid or Flexible PVC, 15mm, 20mm, 25mm, 30mm, 40mm diameter &
2mm or 3mm Think
7. Energy Meter – (Induction type or Electronic Type)
1Ø / 3Ø , 5A /10 A / 15A/ 20A , 50Hz , 230V/440V
8. Power capacitor (For p.f Corrections ) - 1KVAr / 2KVAr / 3KVAr etc., 1Ø /3Ø, Oil or Paper
Insulation, 440V Voltage graded.
4.3 Layout diagram of machines
M.B- Meter Board , M.S.B- Motor Switch Board , MF – Motor Foundation

4. 4
4.4 Single Line Diagram(SLD) of Power Distribution Scheme
4.5 Wiring plan of the Power circuit for a small workshop

5. 5
4.6 Rating of motor for IP (Irrigation Pump) set.
Pump is a machine which lifts water (or Liquid) When driven from lower head to higher head.
In order to drive the pump induction motors are used.
The Power of motor required to drive the pump =
𝟗.𝟖𝟏 × 𝐐 × 𝐇𝐦
𝒉𝒐
kW
Where , Q = Discharge of the pump in m3 /Sec
Hm = Manometric head of water in meter = Suction head + Delivery head + Loss of head
ho = Overall efficiency the pump including that of induction motor.
= hpump + hmotor (Approximately = 0.8×0.8 = 0.64)
For Example : Calculate the HP of induction motor required for centrifugal pump to have a
manometric head of 30M having discharge of 30 Liters / Second.
Solution : Discharge = Q = 30liters/Sec = 30/1000m2/Sec = 0.03m2/Sec
Induction motor Power required =
9.81 × Q × Hm
ℎ𝑜
Kw
=
9.81 × 0.03 ×30
0.64
Kw
= 13.7952KW
In HP =
13.7952
0.735
= 18.77HP ≈ 20HP (Market availability)
4.7 Concept of pump house wiring.
A pump in general may be defined as a machine, when driven from some external source, lifts
water or some other liquid from a lower level to higher level.
The successful working of a centrifugal pump depends upon the correct selection and layout
of its piping system. An extreme care should always be taken in selecting the size of the pipes
and their arrangement.
Pumping systems play important role in providing energy to the fluids in domestic,
commercial and agricultural services. In addition, they are extensively utilized in municipal
water and waste water services as well as in the industrial services for food processing,
chemical, petrochemical, pharmaceutical processing and mechanical industries

6. 6
4.8 Images of Materials
Teak wood board for Motor Control
Flexible conduit pipe P.V.C conduit pipe
Iron Clade Switch Pilot lamp
Rawal plugs
PVC Pipe Coupler
Flexible PVC Pipe Coupler Three Phase Energy meter

7. 7
Example : 01
Prepare the Schedule of materials & Estimation of cost required for installing a 15HP , 440V ,
3Ø , 50Hz induction motor with a layout diagram of wiring. The plane of the workshop is as
show in the figure below:
Solution :
Wiring plan
Single Line diagram of wiring.

8. 8
Assuming ɳ = 0.85 , V= 440V , p.f = cosØ = 0.8
Load Current , IL =
HP of motor ×736
√3×ɳ×cosØ×V
=
15 ×736
√3×0.85×0.8×440
= 21.3Amps
IL= 21.3Amps.
Actual value of load current , I = IL× Factory of safety
= IL×1.5
= 31.95 Amps
From the wiring table the size of the wire from the main switch board to motor terminal is of
16sq.mm , 500V Grade PVC insulated wire.
The size of the conduit pipe from the main switch board to motor switch 31.8mm dia rigid
conduit pipe and from motor starter to motor terminal since 6 wire are running the size of
the rigid conduit pipe is of 38 mm dimeter.
Schedule of materials :
1. 500×450×45 mm Teak wood Varnished Board = 2 Nos.
2. Pilot lamp = 3 Nos.
3. 60A, 500V Grade T.P.I.C = 2Nos. (Main switch & Motor switch)
4. 60A, 500V Grade M.C.B = 1No.
5. Star - Delta Starter 15HP, 400V , 50Hz = 1Set
6. Length of 31.8 mm dia, 500V Grade rigid conduit pipe
= 1.5+0.5+25+0.5+1.5 + (15% Allowance for wastes ) = 34 meter ≈ 12 pieces
7. Length of 31.8 mm dia, 500V Grade flexible conduit pipe = 1 meter.
8. Length of 38 mm dia, 500V Grade rigid conduit pipe
= 1.5+0.5+03+0.5+01+(15% Allowance) = 7 meter ≈ 3 pieces
9. Length of 38mm dia ,500V grade flexible conduit pipe = 1 meter.
10. Length of 16 sq.mm 500V grade PVC insulated copper wire = 2 coil.
11. Length of 1 Sq.mm P.V.C insulated copper wire = 1 coil.
12. 38mm dia. 3mm thick 2.5m length G.I pipe for Earthing = 2 Nos.
13. Earthing bus (wire) 8 SWG G.I (2×2Kg) = 4 Kg.
14. Rawal plugs = 6 dozen.
15. Saddles : a. 31.8 mm diameter = (34×2) = 68 Nos.
b. 38 mm diameter = (7×2) = 14 Nos.
16. Couplers : a. 31.8 mm diameter = 10 Nos.
b. 38 mm diameter = 02Nos.

9. 9
17. Flexible couplers : a. 31.8 mm diameter = 02 Nos.
b. 38 mm dimeter = 02 Nos.
18. Bends : a. 31.8mm diameter = 04Nos.
b. 38 mm diameter = 03 Nos.
19. Miscellaneous items like screws , Bolts, Nuts , sand , cement , etc., = Lumpsum .
Estimation of cost :
Sl.
No List of Materials with Specification
Quantity Required Rate /
Item
Amount
In `
Quantity Units
1 500×450×45 mm Teak wood Varnished Board 02 No. 400=00 800=00
2 Pilot lamp 03 Nos. 20=00 60=00
3 60A, 500V Grade T.P.I.C 02 Nos. 1550=00 3100=00
4 60A, 500V Grade M.C.B 01 No. 2000=00 2000=00
5 Star - Delta Starter 15HP, 400V , 50Hz 01 Set 5500=00 5500=00
6 31.8 mm dia, 500V Grade rigid conduit pipe 12 Pieces 50=00 600=00
7 31.8 mm dia, 500V Grade flexible conduit pipe 01 Meter 35=00 35=00
8 6 sq.mm 500V grade PVC insulated copper wire 02 Coil 7500=00 15000=00
9 1 Sq.mm P.V.C insulated copper wire 01 coil 1050=00 1050=00
10 38mm dia. 3mm thick 2.5m length G.I pipe for
Earthing
02 Nos. 200=00 400=00
11 8 S.W.G - G.I wire (For Earthing ) 04 Kg 100=00 400=00
12 Rawal plugs 06 Dozen 10=00 60=00
13 Saddles- 31.8 mm diameter 68 Nos. 01=00 68=00
14 Saddles- 38 mm diameter 14 Nos. 02=00 28=00
15 Flexible couplers - 31.8 mm diameter 02 Nos. 40=00 80=00
16 Flexible couplers - 38 mm dimeter 02 Nos. 45=00 90=00
17 Bends : a.31.8mm diameter 04 Nos. 05=00 20=00
18 Bends : b.38 mm diameter 03 Nos. 05=00 15=00
19 Miscellaneous Materials such as wooden
wedges, Nut bolts ,Screws, Charcoal salts etc.,
Lumpsum -- -- 500=00
20 Contingency @5% on Materials Cost -- -- -- (29806 × 5%)
1490=00
21 Labour Charge
b. Fixing Meter Board and wiring
c. For Earthing
01
02
No
Nos
1000=00
250=00
1000=00
500=00
Grand Total ` 32,796=00
Total Estimate of cost is Rupees Thirty Two Thousand Seven Hundred ninety six rupees only.

10. 10
Example : 02
In a workshop one 10 Hp , 440V , 50Hz , Three phase induction motor is to be installed.
Prepare a schedule of materials with a layout of wiring. The plan of the workshop is shown
below :
Solution :
Wiring Plan
Wiring Diagram

11. 11
Schedule of Materials :
Assuming ɳ = 0.85 , p.f = cosØ = 0.8
Full Load Current =
𝐻.𝑃×735.5
√3 ×440 ×𝐶𝑂𝑆∅ ×ɳ
=
10 ×735.5
√3 ×440 ×0.8 ×0.85
= 14.19 Amps.
Or Approximate Full load current of motor = H.P × 1.6 = 16 Amps.
Allowing Factor of safety 2
IL = 16 × 2 = 32Amps
Therefore Size of wire required is 10 mm2
Copper wire selected.
1. Length of 10mm2
, 1.1KV class copper wire
From M.B to S.B = 3 (Vertical + M.B to S.B + For Connections)
= 3 (1.5+05+02)
= 25.5 M + 10% wastage
= 28 Meters
2. Approximate current in each lead (6 wires) from starter to motor terminal box
=
𝐹𝑢𝑙𝑙 𝑙𝑜𝑎𝑑 𝑐𝑢𝑟𝑟𝑒𝑛𝑡
√3
=
16
√3
= 9.2 Amps
Therefore 9 to 14 Amps fully Automatic Star – Delta Starter with Voltage coil of 440 V is required
3. Approximate current in each lead (6 wires), Allowing Factor of Safety 2 is ,
= 9.2 × 2 = 18.4 Amps
4mm2
Copper wire is Selected.
Length of 4mm2
, 1.1KV class Copper wire –
= 6 (Along Wall Starter to Ground + UG + From Wall to Motor Foundation + U.G to Ground level + Ground
level to motor Foundation + Foundation to motor Terminal box)
= 6 (1.5+0.5+02+0.5+0.5+1.5) = 6 × 6.5
= 39 + 10% wastage
= 42.9 meter or Half coil
4. Length of 25.4 mm PVC conduit
= (From Ceiling to M.B + M.B to S.B + S.B to Ground + U.G + From takeoff point of S.B to Motor Foundation)
= 1.5 +5 +1.5 +0.5+ 2.5
= 11 Meter + 10% Wastage
= 12.1 Meter ≈ 04 Pieces.
5. Length of 25.4 mm Flexible Conduit
= Motor Control Switch to Starter + Motor Foundation to Motor Terminal box
= 0.5 + 1.5
= 2 Meter
6. Rating of Motor Control switch and Main Switch
Allowing Factor of Safety 2
IL = 16 × 2 = 32 Amps
Therefore 32 Amps , 500V T.P.I.C Switch = 02 Nos.
7. No. of 25.4mm Saddles = Length of conduit in m = 11 Nos. ≈ 01 Dozen
8. 500×450×45 mm Teak wood Varnished Board = 02 No.
9. 38mm dia. 3mm thick 2.5m length G.I pipe for Earthing = 2 Nos.
10. Earthing bus (wire) 8 SWG G.I (2×2Kg) = 4 Kg.

12. 12
11. Rating of Capacitor : RKVA of Capacitor =
𝐻.𝑃
2.5
=
10
2.5
= 𝟎𝟒 RkVA
12. Pilot Lamps = 03 Nos.
13. Batten Holders , 5A , 250V = 03 Nos.
14. 5 Amps , 250V S.P switch = 03 Nos.
15. Miscellaneous, materials such as PVC bends Charcoal , salt , Nuts , Bolts etc,. = Lumpsum
Estimation of cost :
Sl.
No List of Materials with Specification
Quantity Required Rate /
Item
Amount
In `
Quantity Units
1 10mm2 , 1.1KV class copper wire 28 Meters 34=00 952=00
2 4mm2 , 1.1KV class Copper wire ½ Coil 3700=00 1850=00
3 25.4 mm PVC conduit 04 Nos. 40=00 160=00
4 25.4 mm Flexible Conduit 1.5 Meter 20=00 30=00
5 32A, 500V Grade T.P.I.C 02 Nos. 1200=00 2400=00
6 25.4mm Saddles 01 Dozen 50=00 50=00
7 500×450×45 mm Teak wood Varnished Board 02 Nos. 400=00 800=00
8 38mm dia. 3mm thick 2.5m length G.I pipe for
Earthing
02 Nos. 200=00 400=00
9 8 S.W.G - G.I wire (For Earthing) 04 Kg 100=00 400=00
10 4 RKVA of Capacitor 01 No. 1800=00 1800=00
11 Pilot Lamps 03 Nos. 20=00 60=00
12 Batten Holders , 5A , 250V 03 Nos. 20=00 60=00
13 5 Amps , 250V S.P switch 03 Nos. 25=00 75=00
14 Miscellaneous Materials such as Nut, bolts,
bends, Screws, Charcoal salts etc.,
Lumpsum -- -- 500=00
15 Contingency @5% on Materials Cost -- -- -- (9537 × 5%)
477 =00
16 Labour Charge
b. Fixing Meter Board and wiring
c. For Earthing
01
02
No
Nos
1000=00
250=00
1000=00
500=00
Grand Total ` 11,514=00
Total Estimate of cost is Rupees Eleven Thousand Five Hundred Fourteen only.

13. 13
Example : 03
The following machines have to be commissioned in a workshop of inner dimension 6×4 meters.
(a) Lathe machine 3HP, 440V , 3Ø AC - 01 No.
(b) Drilling Machine 1HP, 440V, 3Ø AC - 01 No.
1.Prepare the Layout showing position of Machines and wiring plan.
2.Prepare the Schedule of materials for Power Circuit.
Note : Use surface Conduit System of wiring.
Solutions :
Wiring Plan
Schedule of Materials
1. ICTP Main switch
Assuming ɳ = 0.85 , p.f = cosØ = 0.8
a. For panel board
Full Load Current (IL) =
𝑇𝑜𝑎𝑡𝑎𝑙 𝑖𝑛𝑠𝑡𝑎𝑙𝑙𝑎𝑡𝑖𝑜𝑛 𝑝𝑜𝑤𝑒𝑟 𝑙𝑜𝑎𝑑
√3 ×440 ×𝐶𝑂𝑆∅ ×ɳ
=
4 ×735.5
√3 ×440 ×0.8 ×0.85
= 5.6 Amps.
Allowing factor of safety of 3 , IL = 3×5.67 = 17.03Amps
Market availability 30A ICTP main switch 500V grade = 01 No.
b. For Lathe Machines 3 H.P
Full Load Current (IL) =
𝐻.𝑃 ×735.5
√3 ×440 ×𝐶𝑂𝑆∅ ×ɳ
=
3 ×735.5
√3 ×440 ×0.8 ×0.85
= 4.25 Amps.
Allowing factor of safety of 3 , IL = 3×4. 25 = 12.7 Amps
Market availability 16A ICTP main switch 500V grade = 01 No.
c. For drilling Machines 1 H.P
Full Load Current (IL) =
𝐻.𝑃 ×735.5
√3 ×440 ×𝐶𝑂𝑆∅ ×ɳ
=
1 ×735.5
√3 ×440 ×0.8 ×0.85
= 1.41 Amps.
Allowing factor of safety of 3 , IL = 1× 1.41 = 4.25 Amps
Market availability 5A ICTP main switch 500V grade = 01 No.

14. 14
2. Size and length of wire
a. Size of wire from panel board (P.B) to Switch Board1 (SB1)
IL = 1.6 × HP ------ Approximate
IL = 1.6 × 4 = 6.4 Amps
Allowing factor of safety 2
IL = 6.4 ×2 = 12.8 Amps.
From wiring table 1.5 Sq.mm copper PVC insulated 1.1KV class is selected
Length of wire from PB to SB1 = (1+1+1.5+1+2 Extra) × 3 = 19.5 Meter.
b. Size of wire from SB1 to Motor terminals(Lathe)
IL = 1.6 × 3 = 4.8 Amps
Allowing factor of safety 2
IL = 4.8 ×2 = 9.6 Amps.
From wiring table 1 Sq.mm Copper PVC insulated 1.1KV class is selected.
Length of wire from SB1 to Motor Terminal = (1.5+1.5+1+2(Extra) ) × 3 = 18 Meter
c. Size of wire from SB1 to SB2 and Up to Drilling Machines Terminal
IL = 1.6 × 1 = 1.6 Amps
Allowing factor of safety 2
IL = 1.6 ×2 = 3.2 Amps.
From wiring table 1 Sq.mm Copper PVC insulated 1.1KV class is selected.
Length of wire from SB2 to Motor Terminal = (1+3+1+1.5+1.5+1+2(Extra) ) × 3 = 33 Meter
3. Conduit Accessories
a. Length of conduit 25mm dia, 2mm think PVC
1. Horizontal = 1+1.5+3 = 5.5 Meter
2. Vertical = 1+1+1 = 3 Meter
Total Length of Conduit = 8.5 + (8.5×10% wastage) = 8.5+0.85 = 9.95 ≈ 10 Meter.
b. Length of flexible conduit 25mm dia , 2mm thick PVC
= (1.5+1.5+1+(0.5 Extra) ) × No. of Machines = 4.5 × 2 = 9 Meter.
c. Conduit Accessories suitable for 25mm dia, conduit.
1. conduit Elbows = 03Nos.
2. Conduit Junction = 01 Nos.
3. Saddles = 1 × Length of conduit = 1 (10+9) = 19 Nos.
4. Wiring Accessories
1. 500×450×45 mm Teak wood Varnished Board (2-Switch Board + 1 Panel board ) = 3 Nos.
2. Earthing Electrode 40mm , 2mm thick G.I , 2.5 Meter = 4Nos. (Each Machine 2 Earthing)
3. Earthing bus 8 SWG G.I , 4×2 = 8 Kg.
4. RkVA capacitor –
a. For Lathe Machines =
3
2.5
= 1.2 ≈ 1 RkVA = 1 No
b. For Drilling Machine =
1
2.5
= 0.4 ≈ 1RkVA = 𝟏𝐍𝐨
5. No. of Neon Lamps Flush type = 03Nos.
6. Three way gang box = 01No.
8. Miscellaneous materials such as screws , Bolt , Nut , sand, cement, salt , charcoal, etc., = Lumpsum

15. 15
Example : 04
A small workshop has to be equipped with the following machines of inner dimensions 6×4 meters.
i. A 3HP, 400V , 3-Ø motor for Lathe machine.
ii. A 5KVA , 400V welding Transformer.
Assume efficiency as 85% and power factor of 0.8 for all machines.
a. Draw the wiring diagram for electrical connection starting from main switch.
b. Prepare the Schedule of materials for Power Circuit.
Note : Use surface Conduit System of wiring.
Solutions :
1. ICTP Main switch
Assuming ɳ = 0.85 , p.f = cosØ = 0.8
a. For panel board
Full Load Current (IL) =
𝑇𝑜𝑎𝑡𝑎𝑙 𝑖𝑛𝑠𝑡𝑎𝑙𝑙𝑎𝑡𝑖𝑜𝑛 𝑝𝑜𝑤𝑒𝑟 𝑙𝑜𝑎𝑑
√3 ×440 ×𝐶𝑂𝑆∅ ×ɳ
=
4 ×735.5
√3 ×440 ×0.8 ×0.85
+
5000
440
= 18.74 Amps.
Allowing factor of safety of 3 , IL = 3× 18.74 = 56.23 Amps
Market availability 60A ICTP main switch 500V grade = 01 No.
b. For Lathe machine – 3H.P
Full Load Current (IL) =
𝐻.𝑃 ×735.5
√3 ×440 ×𝐶𝑂𝑆∅ ×ɳ
=
3 ×735.5
√3 ×440 ×0.8 ×0.85
= 4.25 Amps.
Allowing factor of safety of 3 , IL = 3× 4.25 = 12.75 Amps
Market availability 16A ICTP main switch 500V grade = 01 No.
c. For Welding Transformer – 5KVA
Full Load Current (IL) =
𝐿𝑜𝑎𝑑 𝑖𝑛 𝐾𝑉𝐴
440
=
5×1000
440
= 11.36 Amps.
Allowing factor of safety of 3 , IL = 3× 11.36 = 34.08 Amps
Market availability 30A ICTP main switch 500V grade = 01 No.