Estimation Costing of Underground Service Mains for Single, Three Phase

July 24, 2020February 21, 2022 CS Electrical And Electronics

Hello everyone, in this article I will discuss the estimation costing of underground service mains for a single, three phase with taking an example. You can also catch me @ Instagram – Chetan Shidling

Before starting the article if you want to watch a video related to electrical estimation and costing, you can watch my YouTube videos – Click Here.

Also read – Electric Vehicle Questions And Answers.

Estimation Costing of Underground Service Mains

Introduction to Underground Service Mains

Underground service mains are nothing but the conductor used to transmit electricity from low tension lines to the consumer meter board. now I will discuss some points related to underground service mains. Underground service mains once installed it will be life long, not ugly in appearance, skilled laborers are required to the installation of underground service mains, the cost of underground service mains is more.

Q: Prepare an estimate of cost for providing U.G. service mains to feed power supply to an AEH installation having a lighting load of 1020 W and a power load of 3 KW, for a distance of 10 M.

Solution :

List of Materials for U.G Service Mains:

(a). Total Load current

Then calculate the size of the wire, the first thing we must calculate load current and connected load, then find the size of the wire by seeing a wire table.

= (lighting load+heating load)÷230

= (1020 + 3000) ÷ 230

= 17.47 × 2(Factor of safety) = 35 A.

Therefore, the load current is 35 Amps

An underground cable of twin core with steel armored 1.1 VK voltage grade of 16 sq mm is selected.

(b) Length of Cable = 10 + 1 + 3.5 + 4.5 = 19 m.

Therefore, the length of the underground cable is 19 meters.

Note: Length of cable = Horizontal distance + Looseness + Meter-side up to ground level + Ground level to up to pothead on the pole.

Horizontal distance – The horizontal length of underground cable from pole side to meter side.

(c) The length of the Bricks required is 10 M.

Brick is used only for 10m horizontal distance above bricks underground cables are placed.

No of Bricks 11.5 cm × 23 cm × 7.5 cm bricks

= (10 × 100)/23 = 43.47 = 45 Nos.

Therefore, the number of bricks required is 45 Nos.

(d) Iron pothead of 50 A two-terminal, 250 voltage grade is selected = 1 No.

(e) 10 sq mm double sheathed PVC aluminum cable of 250 voltage of length 1 or 2 m for connecting U.G. cable to the distribution line.

(f) Length of GI pipe for drawing U.G cable on pole and meter board side, 40 mm, 3 mm thick, 2.5m on each side = 5 M.

(g) 40 mm GI Pipe 3 mm thick for earthing with 8 SWG G.I wire of 1 kg.

(h) G.I bends of 40 mm dia, 3mm thick = 3 Nos

(i) 60 A, 250 V, Porcelain fuse units = 2 Nos.

(j) Clamps for fixing pothead to pole with bolt and nuts = 1 set.

(k) Clamps for fixing G.I pipe on pole and on the wall with nuts and bolts = 4 sets.

(i) 500 mm × 500 mm × 45 mm well seasoned varnished teak wood board with back cover for meter board = 1 No.

(m) Miscellaneous materials such as salt, coal, nuts, bolts, sand, screws, cement, binding wire, etc.

Cost Of Materials Used In Underground Service Mains

SI.No	Particulars	Units	Quantity	Rate In Rupees	Cost In Rupees
01	16 sq mm twin core steel armoured PVC insulated 1.1 KV grade UG cable	M	19	250.00	4750.00
02	11.5 * 23 * 7.5 cm bricks	No’s	45	20.00	900.00
03	Iron pot head 50 A two terminal / 250 vg for 16 sq mm UG cable	No	1	350.00	350.00
04	10 sq mm double sheathed 250 vg PVC cable	100M (coil)	12	1800	216.00
05	40 mm, 3mm thick GI pipe for laying UG cable and for earthing	M	5 + 2.5 = 7.5	375.00	2812.50
06	GI bends of 40 mm, 3 mm thick	No’s	3	110.00	330.00
07	60 A porcelain fuse units of 250 voltage grade	No’s	2	150.00	300.00
08	Clamps for fixing pot head on pole	Set	1	75.00	75.00
09	Clamps for fixing GI pipe on pole and on the wall	Sets	4	60.00	240.00
10	500 * 500 * 45 mm well seasoned varnished teak wood board	No	1	300.00	300
11	8 SWG GI wire for earthing	Kg	1	150.00	150.00
12	Miscellaneous materials such as sand, cement, bituminous compound salt, coal, bolts, nuts bending wire etc.	L/S			592.50
13	Labour charges
	(a) Laying UG cable				500.00
	(b) Earthing				200.00
14	Contingencies and unforeseen materials at 5% on the above amount	Lump sum			635.00
				Total=	12351.00

For a three-phase connection, everything is the same only thing is you must divide 440V instead of 230V while finding load current.

Let’s take another example.

Q: Prepare an estimate of cost for providing U.G. service mains to feed power supply to an AEH installation having a lighting load of 1000 W and a power load of 2 KW, for a distance of 9 M.

Solution :

List of Materials for U.G Service Mains :

(a). Total Load current

= (lighting load+heating load)÷230

= (1000 + 2000) ÷ 230

= 13.04 × 2(Factor of safety) = 26 A.

An underground cable of twin core with steel armored 1.1 kV voltage grade of 16 sq mm is selected.

(b) Length of Cable = 9 + 1 + 3.5 + 4.5 = 18 m.

Note: Length of cable = Horizontal distance + Looseness + Meter-side up to ground level + Ground level to up to pothead on the pole.

(c) The length of the Bricks required is 10 M.

Brick is used only for 9m horizontal distance above bricks underground cables are placed.

No of Bricks 11.5 cm × 23 cm × 7.5 cm bricks

= (9× 100)/23 = 39.13 = 40 Nos.

(d) Iron pothead of 50 A two-terminal, 250 voltage grade is selected = 1 No.

(e) 10 sq mm double sheathed PVC aluminum cable of 250 voltage of length 1 or 2 m for connecting U.G. cable to the distribution line.

(f) Length of GI pipe for drawing U.G cable on pole and meter board side, 40 mm, 3 mm thick, 2.5m on each side = 5 M

(g) 40 mm GI Pipe 3 mm thick for earthing with 8 SWG G.I wire of 1 kg.

(h) G.I bends of 40 mm dia, 3mm thick = 3 Nos

(i) 60 A, 250 V, Porcelain fuse units = 2 Nos.

(j) Clamps for fixing pothead to pole with bolt and nuts = 1 set.

(k) Clamps for fixing G.I pipe on pole and on the wall with nuts and bolts = 4 sets.

(i) 500 mm × 500 mm × 45 mm well seasoned varnished teak wood board with back cover for meter board = 1 No.

(m) Miscellaneous materials such as salt, coal, nuts, bolts, sand, screws, cement, binding wire, etc.

Let’s take an example for a three-phase underground system

Q: Estimate of cost for providing U.G. service mains to feed power supply to an AEH installation having a lighting load of 6000 W and a power load of 4 KW, for a distance of 15 M. For a three-phase system

Solution :

List of Materials for U.G Service Mains :

(a). Total Load current

consider the unity power factor.

= (lighting load+heating load)÷230

= (6000 + 4000) ÷ 440

= 22.72 × 2(Factor of safety) = 45.45 A.

An underground cable of four core with steel armored 1.1 kV voltage grade, size of wire calculate from wire table.

(b) Length of Cable = 15 + 1 + 3.5 + 4.5 = 24 m.

Note: Length of cable = Horizontal distance + Looseness + Meter-side up to ground level + Ground level to up to pothead on a pole.

(c) The length of the Bricks required is 10 M.

Brick is used only for 24m horizontal distance above bricks underground cables are placed.

No of Bricks 11.5 cm × 23 cm × 7.5 cm bricks

= (15× 100)/23 = 65.21 = 65 Nos.

(d) Iron pothead of 50 A four terminal, 250 voltage grade is selected = 1 No.

(e) Double sheathed PVC aluminum cable of 250 voltage of length 1 or 2 m for connecting U.G. cable to the distribution line.

(f) Length of GI pipe for drawing U.G cable on pole and meter board side, 60 mm, 3 mm thick, 2.5m on each side = 5 M

(g) 60 mm GI Pipe 3 mm thick for earthing with 8 SWG G.I wire of 1 kg.

(h) G.I bends of 60 mm dia, 3mm thick = 3 Nos

(i) 60 A, 250 V, Porcelain fuse units = 4 Nos.

(j) Clamps for fixing pothead to pole with bolt and nuts = 1 set.

(k) Clamps for fixing G.I pipe on pole and on the wall with nuts and bolts = 4 sets.

(i) 500 mm × 500 mm × 45 mm well seasoned varnished teak wood board with back cover for meter board = 1 No.

(m) Miscellaneous materials such as salt, coal, nuts, bolts, sand, screws, cement, binding wire, etc.

I hope this article may help you all a lot. Thank you for reading. If you have any doubts related to this article “estimation costing of underground service mains”, then comment below.

Tag: Estimation costing of underground service mains.

Also, read: