General Specification
Section – 7
General Specification
TECHNICAL SPECIFICATION
A. SPECIFICATION OF MATERIALS
1.
CEMENT
Cement shall be of ordinary gray Portland cement conforming to "Specification for Portland Cement (ASTM-C150 - 695 Type-I)". Some of the important requirements shall be as follows :
(a)
(b)
Chemical Requirements
Magnesium oxide (MgO) maximum Sulphur Trioxide (SO3)
5%
(i)
When Tricalcium Aluminate (3 CaO A12O3) is 8% or less, maximum
2.5%
(ii)
When Tricalcium Aluminate (3 CaO A12O3) is more than 8%, maximum
3.0%
(iii)
Loss on Ignition, maximum
3.0%
(iv)
Insoluble Residue, maximum
0.75%
Physical Requirements
(i)
(ii)
Fineness, specific surface (sq.cm per gram)
Turbidimeter Test (C-115 ASTM)
1600
Average value, minimum
1600
Minimum value, any one sample
1500
Soundness
Autoclave expansion (C-151 ASTM), maximum
(iii)
0.8%
Time of Setting
Gilmore Test (C-266 ASTM)
(iv)
Initial Set, not less than
45 Minutes
Final set, not more than
Compressive strength
8 hours
The compressive strength of mortar cubes, composed of 1 part of cement and 2.75 parts
graded standard (ottowa) sand, by weight, prepared and tested in accordance with Method C109 (ASTM) shall be equal to or higher than the values specified for the ages indicated below
:
1 day in moist air, 2 days in water 127 Kg/cm2
1 day in moist air, 6 days in water 197 Kg/cm2
1 day in moist air, 27 days in water 282 Kg/cm2
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136
General Specification
(v)
Tensile strength
The tensile strength of mortar cubes, composed of 1 part cement and 3 parts graded standard
(ottowa) sand, by weight, prepared and tested in accordance with method C-190 (ASTM)
shall be equal to or higher than the values specified for the ages indicated below:
1 day in moist air, 2 days in water 10.6 Kg/cm2
1 day in moist air, 6 days in water 19.4 Kg/cm2
1 day in moist air, 27 days in water 24.6 Kg/cm2
(c)
Test
Number of test to be performed shall be determined by the Employer/University Engineer and the cost
of testing including all incidental charges shall be borne by the Contractor. The test shall be performed
in the Laboratory approved by the Employer.
2.
SAND
For both Coarse and Medium
(i)
General Characteristics
Sand shall consist of natural sand, manufactured sand or a combination thereof.
(ii)
Deleterious substances
(a)
The amount of deleterious substances in sand shall not exceed the limit prescribed below:
LIMITS FOR DELETERIOUS SUBSTANCES IN SAND FOR CONCRETE
ITEM
MAXIMUM PERCENT BY
WEIGHT OF TOTAL SAMPLE
METHOD OF TEST
Clay lumps
1.00
ASTM C-142
Materials finer than No.200 sieve
3.00
ASTM C-117
Coal and Lignite
0.50
ASTM C-125
Light weight particles floating on
liquid of density 2000 kg/cum.
0.50
ASTM C-123
(iii)
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Organic Impurities
1.
Sand shall be free from injurious amounts, organic impurities, except herein provided, Sand
subjected to the ASTM C-40 for organic impurities and producing a colour darker than the
standard shall be rejected.
2.
Sand failing in the test may be used provided that the discoloration is due principally to the
presence of small quantities of coal, lignite, or similar discrete particles.
3.
Sand failing, in the test may be used, provided that when tested for the effect of organic
impurities on strength of mortar, the relative strength at 7 and 28 days calculated in
accordance with section 10 of the Method of Test for Effect on Organic Impurities in Fine
Aggregate on strength of Mortar (ASTM - Designation: (86 - 63T), is not less than 95%.
137
General Specification
(iv)
Soundness
Sand subject to five cycles of the soundness test (ASTM C-88) shall show a loss, weighted in
accordance with the grading of a sample complying with the limitations set forth herein before, not
greater than 10 percent when sodium sulphate is used or 15 percent when magnesium sulphate is used.
(v)
Grading for Coarse Sand
(a)
Sieve analysis
Sand shall be graded within the following limits when tested by method ASTM- C-135 and C125.
(b)
(vi)
PERCENTAGE OF WEIGHT PASSING
6mm
100
No.4 (4.76mm)
95 to 100
No.8 (2.38mm)
80 to 100
No.16 (1.19mm)
50 to 85
No.30 (0.595mm)
25 to 60
No.50 (0.297mm)
10 to 30
No.100 (0.139mm)
2 to 0
The sand shall have not more than 45 percent by weight retained between any two
consecutive sieves of these shown in paragraph (a), and its Fineness Modulus shall be not less
than 2.50 or more than 3.10.
Grading for Medium Sand
(a)
(b)
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SIEVE
Sieve Analysis : Sand shall be graded within the following limits when tested by Method
ASTM C-135 and C-125.
SIEVE
PERCENTAGE OF WEIGHT
PASSING
3mm
-
No.4 (4.76mm)
100
No.8 (2.38mm)
95 to 100
No.16 (1.19mm)
85 to 100
No.30 (0.595mm)
70 to 85
No.50 (0.297mm)
10 to 40
No.100 (0.139mm)
2 to 15
The sand shall have not more than 50 percent by weight retained between any two
consecutive sieve of these shown in paragraph (a) and its Fineness Modulus shall be not less
then 1.50. The sand should not be retained by more than 25% between sieve No.50 and sieve
No.100.
138
General Specification
(vii)
Sampling, Testing and Approval
Sample of sand selected by the Employer/University Engineer shall be deposited by the Contractor to
the Laboratory approved by the Employer for testing in laboratory. The arrangement to testing in
laboratory shall be done by the Employer but the cost of testing and all incidental charge in this
connection shall be borne by the Contractor.
The quantity of sand to be tested shall be at the discretion of the Employer/University Engineer. If any
sample of sand are found deficient in test, more tests shall be done.
If the test results are satisfactory, the Consultant/University Engineer will approve the sand for
acceptance.
If the test results are not satisfactory, the entire lot from which the samples had been taken may be
rejected or at the request of the Contractor, he may be allowed to restack the sand leaving the relative
inferior sand out.
After the re-stacking is done a second set of test will be run on them and if the test results are
unsatisfactory, the lot will be rejected. All rejected sands shall be stored in an exclusive area as
indicated by the Employer/University Engineer and shall be removed from the site by the Contractor at
his own cost.
3.
Coarse Aggregate
3.1
General Characteristics
Coarse aggregate shall consist of crushed stone of Boulders (Min. 5”) of Bholaganj Standard
conforming to the requirements of this specification.
.
3.2
Grading
Coarse aggregates shall conform to the requirements prescribed in Table-2 for the size number
specified.
Note : The ranges shown in Table-2 are by necessity very wide in order to accommodate nationwide
conditions. For quality control of any specific operation, a producer should develop an average
gradation of the particular source and production facilities, and control the gradation within
reasonable tolerances from this average.
3.3.
Deleterious Substances
3.4
Except for the provisions of 10.3, the limits given in Table-3 shall apply for the class of coarse
aggregate designated in the purchase order or other document (Note-9). If the class is not specified,
the requirements for Class-3S, 3M, or 1N shall apply in the severe, moderate, and negligible
weathering regions, respectively (See Table-3).
Note : The specified of the aggregate should designate the class of coarse aggregate to be used in
the work, based on weathering severity, abrasion, and other factors of exposure. (See Table-3). The
limits for coarse aggregate corresponding to each class designation are expected to ensure
satisfactory performance in concrete for the respective type and location of construction. Selecting a
class with unduly restrictive limits may result in unnecessary cost if materials meeting those
requirements are not locally available. Selecting a class with lenient limits may result in
unsatisfactory performance and premature deterioration of the concrete. While concrete in different
parts of a single structure may be adequately made with different classes of coarse aggregate, the
specifier may wish to require the coarse aggregate for all concrete to conform to the same more
restrictive class to reduce the chance of furnishing concrete will the wrong class of aggregate,
especially on smaller projects.
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139
General Specification
4.
3.5
Coarse aggregate for use in concrete that will be subject to wetting, extended exposure to humid
atmosphere, or contact with moist ground shall not contain any materials that are deleteriously
reactive with the alkalis in the cement in an amount sufficient to cause excessive expansion of
mortar or concrete except that if such materials are present in injurious amounts, the coarse
aggregate may be used with a cement containing less than 0.60% alkalis calculated as sodium oxide
equivalent (Na2 + 0.658K2O) or with the addition of a material that has been shown to prevent
harmful expansion due to the alkali aggregate reaction.
3.6
Coarse aggregate having test results exceeding the limits specified in Table-3 may be accepted
provided that concrete made with similar aggregate from the same source has given satisfactory
service when exposed in a similar manner to that to be encountered; or, in the absence of a
demonstrable service record, provided that aggregate produces concrete having satisfactory relevant
properties.
3.7
Hardness : Coarse aggregate shall conform to Abrasion Test.
Methods of Sampling and Testing
4.1
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Sample and test the aggregates in accordance with the following methods, except as otherwise
provided in this specification. Make the required tests on test samples that comply with
requirements of the designated test methods. The same test sample may be used for sieve analysis
and for determination of materials finer than the 75-µm (No. 200) sieve. Separated sizes from the
sieve analysis may be used in preparation of samples for soundness or abrasion tests. For
determination of all other tests and for evaluation of potential alkali reactivity where requried, use
independent test samples.
4.1.1
Sampling – Practice D 75 and Practice D 3665.
4.1.2
Grading and Fineness Modulus - Method C 136
4.1.3
Amount of Material Finer than 75-µm (No. 200) Sieve – Test Method-C 117.
4.1.4
Organic Impurities – Test Method C 40.
4.1.5
Effect of Organic Impurities on Strength – Test Method C 87.
4.1.6
Soundness – Test Method C 88.
4.1.7
Clay Lumps and Friable Particles – Test Method C 142.
4.1.8
Coal and Lignite – Test Method C 123, using a liquid of 2.0 specific gravity to remove the
particles of coal and lignite. Only material that is brownish-black, shall be considered coal
or lignite. Coke shall not be classed as coal or lignite.
4.1.9
Abrasion of Coarse Aggregate – Test Method C 131 or Test Method C 535.
4.1.10
Freezing and Thawing – Procedures for making freezing and thawing tests of concrete are
described in Test Method C 666.
4.1.11
Chart – Test Method C 123 is used to identify Particles in a samples of coarse aggregate
light Er than 2.40 specific gravity, and Practice C 295 to identify which of the particles in
the light fraction are chart.
140
General Specification
TABLE -1 Limits for Deleterious Substances in Fine
Aggregate for Concrete
Item
Weight Percent for
Total Sample, Max
Clay lumps and friable particles
3.0
Material finer than 75-µm (No. 200) sieve:
Concrete subject to abrasion
3.0A (In roads and pavements)
All other concrete
5.0 A
Coal and lignite :
Where surface appearance of concrete is
of importance
0.5 (for fair face concrete)
All other concrete
1.0
A
In the case of manufactured sand, if the material finer than the 75-µm (No. 200) sieve consists of
the dust of fracture, essentially free of clay or shale, these limits may be increased to 5 and 7%,
respectively.
TABLE – 2 Grading Requirements of Coarse Aggregates
Siz
e
No.
Nominal
size
(Sieves with square
Opening)
56
57
6
Amount Finer than Each Laboratory Sieve (Square Opening), Weight Percent
100mm
(4 in)
90mm
(3½
in)
75mm
(3 in)
63mm
(2½ in)
50mm
(2 in)
37.5mm
(1½ in)
25mm
(1 in)
19mm
(3/4 in)
12.5mm
(½ in)
9.5mm
(3/8 in)
4.75mm
(No.4)
2.36mm
(No.8)
1.18mm
(No.16)
25.0 to 9.5mm
(1 to 3/8 in.)
..
..
..
..
..
100
..
..
..
..
..
..
100
..
0 to 10
0 to 5
..
19.0 to 4.75mm
..
..
..
..
..
..
0 to 15
0 to 5
..
..
..
..
..
..
..
..
100
0 to 5
..
..
..
..
..
..
..
0 to 15
0 to 5
..
..
..
..
..
..
..
..
..
20 to
55
40 to
70
85 to
100
0 to 10
..
90 to
100
90 to
100
100
10 to
40
25 to
60
20 to
55
..
0 to 5
..
40 to
85
..
0 to 15
25.00 to 4^N75mm
(1 in. to No.4)
90 to
100
95 to
100
100
10 to
30
0 to 10
0 to 5
(3/4 in to 3/8 No.)
67
7
8
19.0 to 4.75mm
(3/4 in. to No.4)
12.5 to 4.75mm
(½ in. to No.4)
9.5 to 2.36mm
(3/8 in to No.8)
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141
90 to
100
100
General Specification
TABLE 3 Limits for Deleterious Substances and Physical Property
Requirements of Coarse Aggregate for Concrete
Class
Designation
Type of Location of
Concrete Construction
1M
Footings, foundations,
columns, and beams
not exposed to the
weather, interior floor
slabs to be given
coverings.
Interior floors without
coverings
2M
3M
4M
5M
Foundation
walls
above grade, retaining
walls,
abutments,
piers, girders, and
beams exposed to the
weather
Pavements,
bridge
decks, driveways and
curbs, walks, patios,
garage floors, exposed
floors and porches, or
waterfront structures
subject to frequent
wetting.
Exposed architectural
concrete
Maximum Allowable, %
Sum of Clay
Material
Coal and
Lumps, Friable Finer Than
Lignite
Particles, and
75-µm
Chart (Less
(No. 200)
Than 2.40 sp
sieve
gr SSD)
Moderate Weathering Regions
Clay
Lumps
and
Friable
Particles
Chart (Less
Than 2.40
sp gr SSD)
Abrasion
Magnesium
Sulfate
Soundness
(5 cycles)B
10.0
...
...
1.0D
1.0
50
5.0
...
...
1.0D
0.5
50
...
5.0
8.0
10.0
1.0D
0.5
50
18
5.0
5.0
7.0
1.0D
0.5
50
18
3.0
3.0
5.0
1.0D
0.5
50
18
...
B The allowable limits for soundness shall be 12% if sodium sulphate is used.
D This percentage may be increased under either of the following conditions : (1) if the material finer than the 75-µm sieve is
essentially free of clay or shale the percentage may be increased to 1.5: or (2) if the source of the fine aggregate to be used in the
concrete is known to contain less than the specified maximum amount passing the 75-µm sieve (Table-1). The percentage limit (L)
on the amount in the coarse aggregate may be increased to L = 1 + [(P)/(100-P)] (T-A), where P=percentage of sand in the concrete
as a percent of total aggregate, T = the Table-1 limit for the amount permitted in the fine aggregate, and A = the actual amount in the
fine aggregate. (This provides a weighted calculation designed to limit the maximum mass of material passing the 75-µm sieve in the
concrete to that which would be obtained if both the fine and coarse aggregates were supplied at the maximum tabulated percentage
for each of these ingredients).
4.
Boulders
4.1
Colour
The Boulders shall be very dense and white in colour, Black or coloured boulders shall not be
accepted.
4.2
Size
The size of Boulder shall very from 63.5 mm (2.5”) to 127 mm (5”).
4.3
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Specific Gravity should be 2.70 to 2.80.
142
General Specification
4.4
Compressive Strength or Crushing Strength
The compressive / crushing strength of boulder not less than 850 kg / cm2 (12,000 psi).
4.5
Deleterious Substances
The amount of deleterious substances in boulders shall not exceed the limits given below :
Sl. No.
Item
1.
2.
3.
Clay Lumps
Soft Particle
Chart as an impurity that will
disintegrate in five cycles of the
soundness test
Materials finer than No. 200
Sieve
Coal and lignite
4.
5.
4.6
Max. percent by
weight of total
0.25
5.00
5.00
Method of Test
ASTM C - 142
ASTM C – 235
ASTM C – 88
1.00
ASTM C – 117
0.50
ASTM C – 123
Soundness
Boulders subjected to five cycles of the soundness test (ASTM C-88) shall show a loss, not greater
than 12 percent when sodium sulphate is used and 18 percent when magnesium sulphate is used.
5.
4.7
Boulders tested for abrasion (ASTM C – 131) shall have a loss not more than 35 percent.
4.8
Crushing value should not exceed 30%.of Crushing Strength.
4.9
Porosity Test : Maximum 1%.
BRICKS
A.
Ordinary First Class Machine made Bricks
Brick shall be machine made ordinary First Class brick. Bricks unless otherwise specified shall be first
class of size 241mm x 114mm x 70mm. Those shall be uniform in size and colour thoroughly and
evenly burnt. These shall not break when thrown on the ground against one another from a height of
1.5M and shall give a metallic sound when struck against one another. The bricks shall be free from
cracks or flaws. The brick shall have a minimum compression strength of 141 kg/cm2 on flat for any
individual brick and 176 kg/cm2 on flat for average of any five bricks. The bricks shall not absorb more
than one sixth of their weight of water when immersed for one day.
The bricks shall be M.B.CO. or Conforce standard or approved best quality.
The bricks shall be kiln and gas/coal burnt.
B.
C.
Ordinary First Class bricks
The specification of Ordinary First Class Bricks shall be as that of Ordinary First Class Machine made
Bricks and it may be of any brick field excepting Saline Zone.
Picked Jhama Bricks
The specification of picked jhama bricks shall be as that of ordinary first class machine made bricks
except and provided that the bricks shall have a minimum compression strength of 253 kg/ cm2 on flat
for any individual bricks and 316 kg/cm2 on flat for average of any five bricks.
The bricks shall be kiln and gas/coal burnt.
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143
General Specification
D.
Test
The number of bricks to be tested shall be at the discretion of the Employer/University Engineer.
Only, after the bricks are approved by Consultant/University Engineer, it shall be used in the work.
The test shall be performed in the Laboratory approved by the Employer.
6.
REINFORCING STEEL
A.
General
The Mild Steel Rod shall conform ASTM A 15-64 (Structural Grade) and High Strength Rod shall
conform ASTM A 432-64.
The ends of the bar shall be machine sheared perpendicular to the axis of the bar.
The bars shall be free from injurious defects and shall have a workman like finish.
B.
Chemical Properties
The steel shall conform to the following requirements as to chemical composition :
Phosphorus, maximum percent
Open hearth, basic oxygen or electric furnace
Basic
....
0.05
Acid
....
0.08
Acid bessemer and open hearth, basic oxygen or electric furnace.
Rephosphorized ....
0.12
C.
Process
The bars shall be rolled from new and clean billet directly reduced from ingots of properly identified
heats of open hearth, basic oxygen or electric furnace steel or its of acid bessemer steel.
D.
Tensile properties and bending properties
PROPERTIES
Yield Strength
In Mpa
ii) Ultimate Tensile Strength
In Mpa
iii) Minimum Elongation
a) dia upto 18 mm
b) dia 20 & 22 mm
c) dia 25 mm
d) dia 30 mm
iv) Bend Test
The specimen shall stand being bent at
(all sizes) room temperature around a pin
without cracking on the outside of the
bent portion. The relation between the
diameter of the pin(t) and the dia- meter
of the specimen (d) shall be
MILD STEEL (PLAIN)
HIGH STRENGTH
DEFORMED
i)
E.
235
394
In 200mm length
24%
23%
22%
20%
180o Bend
t=4d
415
590
In 200mm length
11%
10%
9%
7%
90o Bend
upto 16mm t=4d
18mm to 22mm t=5d
25mm t=5d
30mm t=6d
Dimensional requirement for both mild steel and high strength
The nominal diameter, perimeter and cross -sectional area of a deformed bar (is equivalent to that of a
plain bar having the same standard weight).
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144
General Specification
F.
Bar size
Standard weight in
Kg/M
Diameter in mm
Cross sectional
Area in cm2
Perimeter in mm
6mm
0.222
6
0.283
18.85
8mm
0.395
8
0.503
25.13
10mm
0.616
10
0.785
31.42
12mm
0.887
12
1.13
37.70
16mm
1.58
16
2.01
50.27
18mm
1.99
18
2.54
56.55
20mm
2.47
20
3.14
62.83
22mm
2.98
22
3.80
69.12
25mm
3.85
25
4.91
78.54
30mm
5.55
30
7.07
94.25
Permissible variation from standard weight
Bar size
G.
Mild Steel Rods
Plain
Deformed or Twisted Deformed
For lot 6mm
 5%
 3.5% for all sizes
 3.5% for all sizes
Above 6mm
 3.50%
-
-
For individual 6mm
 10%
 6% for all sizes
 6% for all sizes
Above 6mm
 6%
-
-
Requirement of Deformation (both for Mild steel and High strength steel)
(a)
Deformations shall be spaced along the bar at substantially uniform distances. The deformation
on opposite sides of the bar shall be similar in size and shape.
(b)
The deformations shall be placed with respect to the axis of the bar so that the included angle
is not less than 45 deg. Where the line of deformation forms an included angle with the axis of
the bar of from 45 to 70o deg. inclusive, the deformations shall alternately reverse in direction
on each side, or those on one side shall be reversed in direction from these on the opposite
side. Where the line of deformations is over 70 deg. a reversal in direction is not required.
The average centre to centre or distance between deformation on each side of the bar shall not
exceed seven tenths of the nominal diameter of the bar.
(c)
(d)
The overall length of deformations shall be such that the gap between the extreme ends of the
deformations on opposite sides of the bar shall not exceed 12 percent of the nominal
perimeter of the bar. Where the extreme ends terminate in a longitudinal rib, the width of the
longitudinal rib shall be considered the gap. Where more than two longitudinal ribs are
involved, the total width of all longitudinal ribs shall not exceed 25 percent of the nominal
perimeter of the bar further more, the summation of gaps shall not exceed 25 percent of the
nominal perimeter of the bar. The nominal perimeter of the bar shall be 3.14 times the nominal
diameter.
(e)
The minimum height of deformations shall be not less than the following percentages of the
nominal diameter of the bar.
Diameter of the M.S. Rod
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High Strength
deformed Rod
Minimum height of deformation in
145
General Specification
percent of nominal diameter of bar
10mm dia
4
12mm dia
4
4
16mm dia
20mm dia to 38mm dia
(f)
(g)
The spacing, height, and gap of deformations shall conform to the requirements prescribed
below :
Bar size
Maximum average
spacing in mm
Minimum
average height in
mm
Max. Gap in mm
(Chord of 12 % of
nominal perimeter)
10mm dia
6.7
0.38
3.5
12mm dia
8.9
0.51
4.9
16mm dia
11.1
0.71
6.1
18mm and 20mm dia
13.3
0.96
7.3
22mm dia
15.5
1.11
8.5
25mm dia
17.8
1.27
9.7
28mm dia
20.1
1.42
10.9
30mm and 32mm dia
22.5
1.63
12.37
Measurements
(i)
The average spacing of deformations shall be determined by dividing a measured
length of the bar specimen by the number of individual deformations on any one side
of the bar specimens. A measured length of the bar specimen shall be considered the
distance from a point on a deformation to a corresponding point on any other
deformation on the same side of the bar.
(ii)
7.
5
The average height of deformations shall be determined from measurements made on
not less than two typical deformations. Determinations shall be based on three
measurements per deformations, one at the centre of the over-all length and the other
two at the quarter points of the over-all length.
TIMBER
The timber to be used shall be of first class quality of the specimen as noted in the schedule of items.
It shall be from the heart of a matured and sound tree and shall be uniform in substance. The timber shall be free
from large or dead knots, cracks, flaws, shakes, blemishes or any other defects. The timber shall not contain any
sap-wood and shall not have surface cracks or chipping in edges and corners.
The timber shall be well seasoned and shall not contain more than 12% moisture by weight.
B. MATERIAL FOR PLUMBING WORK
1.
PIPES
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146
General Specification
(i)
H.C.I. pipes
Cast Iron pipes shall be of MAANCO brand or approved best quality and shall conform to ASTM A7442. The pipes shall be painted, both outside and inside in 2 coats of "Thick cote" Epoxy (Special two
pack product catalyst/curing agent made by BERGER/approved best quality).
(ii)
A.C. Pipes
Asbestos Cement pipes shall conform to ASTM C-42 -63T in case of non-pressure sewer or drainage
pipe and to ASTM C29-64T in case of pressure pipes for water supply.
The former category of pipe shall be of class 1500. The length of the pipe shall be at least 12 ft.
The class of pipe in the case of pressure pipes shall be 100, 150 or 200 as specified. If not specified, the
class shall be taken as 150.
(iii)
R.C. Pipes
R.C. pipes shall be manufactured by ROTO BURN & CO. or manufacturers approved by the
Consultant. ASTM C-361, (H50 class) shall be followed unless superseded by the following
requirements. Length of pipe shall be 2.44M. Concrete used in pipes shall be of 28 days 150mm x
300mm cylinder strength of 316 kg/cm2 minimum.
Dimension and Re-inforcing steel
(iv)
Dia
Barrel
thickness
Size of M.s.
Rod or Wire
Spacing of
circumferencial steel
No. of
longitudinal
rods or wire
Strength Test
Requirement,
3-edge bearing
method load per ft.
100mm
18mm
No.8 SWG
75mm
3
2250
150mm
22mm
No.8 SWG
75mm
4
2250
225mm
25mm
No.8 SWG
75mm
5
2250
G.I. pipes
The Galvanised Iron pipes to be used in the work shall conform to ASTM A 120-57T, welded or
seamless. The dia of pipes mentioned in the Schedule of Item are nominal diameters. The pipes shall be
coated with Zinc inside and outside by hot dip process and the Zinc used for the coating shall be any
grade of Zinc conforming to the specifications for slab Zinc. The weight of coating shall be less than 2.0
oz. per square foot. Each length of the pipe shall be tested at the mill to the Hydrostatic Test pressure
and Test pressure shall be 84 kg / cm2.
The pipes shall also conform to the following tables.
The exterior surface of the pipes shall be painted in 2 coats of "Thick cote" Epoxy special 2 pack
product (Catalyst/Curing Agent) made by BERGER/approved best quality.
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General Specification
(v)
Nominal size in mm
(diameter)
Outside diameter
mm
Wall thickness in mm
Weight in kg/M
12mm
21.34mm
2.77mm
126
18mm
26.67mm
2.87mm
1.68
25mm
33.40mm
3.38mm
2.50
38mm
48.26mm
3.68mm
4.06
50mm
60.33mm
3.91mm
5.48
62mm
73.03mm
5.16mm
8.66
P.V.C. Pipe
The PVC pipe shall conform to ASTM Designation D 1785 - 64T, 80 schedule.
The wall thickness with tolerance is noted below :
2.
Nominal size
Wall thickness
(in mm)
Tolerance
50mm
5.54
+ 0.026
75mm
7.62
+ 0.036
100mm
8.56
+ 0.040
125mm
9.53
+ 0.045
150mm
10.97
+ 0.052
PIPE FIXTURE
(i)
Gate Valve
Gate Valves of sizes 62mm to 150mm dia shall be made of Cast Iron, Bronze trim, conforming to
specification B.S. 3464, 1962, "Double Dise" type with non-rising stem. Gate valves of size 50mm dia
shall be made of Copper Alloy, bronze trim, conforming to specifications B.S. 1952, 1964, "Double
Disc" type with non-rising stem.
(ii)
Screw Down Valve
Screw Down Valves shall be of plain brass and of best quality available in Bangladesh.
(iii)
Float and Ball Valve :
Float and Ball valve shall be brass and of best quality available in Bangladesh.
(iv)
Bib cock, Pillar cock
These shall be chromium plated and shall be of best quality available in Bangladesh. The item shall
conform the sample kept in the Office of the Consultant having marked "Best Quality" The tenderer
shall see sample before quoting their rate.
(v)
H.C.I. Fitting : e.g. P/S trap, Nahani trap, Floor trap, etc. The H.C.I. fittings shall be of MAANCO
brand or approved best quality.
(vi)
Siphon
The siphon used in low cistern shall be of SHANKS or approved best quality.
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General Specification
C.
SPECIFICATIONS FOR ELECTRICAL WORKS (MATERIALS AND WORKS)
A.
GENERAL
1.0.
SCOPE OF WORK
This chapter covers all equipment/ materials and operations in connection with internal and external
electrification and similar other installation works covering buildings and related other establishments as
indicated on the drawings. All works shall be completely in conformity with the Rules and Regulations as stated
below.
2.0.
STANDARD CODE AND REGULATIONS FOR INSTALLATION
The installation in general shall be carried out in conformity with the Electricity Rules of the Govt. of Bangladesh
(Indian Electricity Act and Rules as adopted in Bangladesh) and the 14th edition of the Regulation for Electrical
Equipment of Buildings of the Institute of Electrical Engineers (London), hereinafter referred as 'I.E.E. Wiring
Regulations' and the British Standard Code of practice for the relevant works. But where the under noted
specifications differs from these rules and standards, the specifications written hereunder shall be followed. Any
special requirement of the Electrical Inspector, Govt. of Bangladesh or the Power Development Board/Dhaka
Electric Supply Authority or the Telegraph and Telephone Board or any other Legally constituted Authority shall
also be complied with, at Contractor's cost within the Contract Price.
3.0.
GENERAL REQUIREMENTS
3.1
The drawings related to the works indicate only the general arrangement of the electrical installation.
Details of proposed departures due to actual field condition or other pause shall be submitted to the
Engineer. for approval. The Contractor shall carefully examine the drawings and shall be responsible for
the proper installation of materials, fixtures and equipment in each unit as indicated without substantial
alteration.
3.2
Climatic and Atmospheric Conditions :
The installations, equipment and materials shall be installed both externally and internally and shall
therefore, be designed and built to give efficient and reliable service continuously at the normal voltage
and current rating in the prevalent climatic and atmospheric conditions at the relevant site.
3.3
Specifications :
Materials required which are not covered by the detailed specifications shall be as recommended by the
equipment manufacturer or in consistent with good practice and approved by the Engineer.
3.4
Drawings :
The drawings show the general arrangement of all circuitry, wiring, feeders, cables and race ways etc.
however, where local conditions necessitate a re-arrangement shall prepare and submit for approval
drawings of the proposed re-arrangement. Because of the small scale of the drawings it is not possible to
indicate all offsets, fitting and accessories which may be required. The Contractor shall carefully
investigate the structural and finish conditions affecting all of his works and shall arrange such works
accordingly, furnishing such fittings, access traps, inspection boxes and accessories as may be required
to meet such conditions. The Contractor , if necessary shall prepare a shop drawing indicating the exact
location of conduits and wiring for approval of the Engineer.
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General Specification
3.5
Cutting and Repairing :
The work shall be carefully laid out in advance and any cutting of construction shall be done only with
the written permission of the Engineer. Cutting shall be carefully done and mending good the damages
to the building as a result of cutting for installation, piping, wiring for equipment etc. shall be done by
skilled mistries of the trade involved, at no additional expense to the Employer.
3.6
Protection of Fixture:
Conduit and pipe opening shall be closed with caps of plugs during installation. Fixture fittings and
equipment shall be adequately protected against dirt, water and chemical or mechanical injury. At the
completion of the work, fixture, materials and equipment shall be thoroughly cleaned and delivered in a
condition satisfactory to the Engineer.
3.7
Notice :
The Contractor shall give all required notices to and maintain liaison with Electrical Inspector,
Government of Bangladesh and to the Electric Supply Department of Power Development Board of the
area of the work concerned or similar other organisations and any other legal Authority Regulating the
electrical works or installation.
3.8
Execution and Superintendence :
The works shall be carried out only by licensed workman authorized by the Government or any other
legal Authority set up for the purpose to undertake such works under the provision of the Indian
Electricity Act. 1939 and Rules as adopted in Bangladesh and under the direct supervision of a whole
time electrical supervisor having certificate of competency for the type of work under execution.
Particulars along with a Photostat copy of the competency certificate of the electrical supervisor shall be
submitted to the Engineer. before commencing the work.
4.0.
APPROVAL AND LIST OF MATERIALS, FIXTURE AND EQUIPMENT
As soon as practicable and within 30 days after date of receipt of executed contract and before any materials
fixtures or equipment are purchased, the contractor shall submit to the Engineer for approval a complete list, in
triplicate, of materials, fixtures and equipment to be incorporated in the work, together with the names and
addresses of the manufactures and their catalogues numbers and trade names. The contractor shall also furnish
other detailed information where so directed, under the various items. No consideration will be given to partial
lists submitted from time to time. Approval of materials will be based on manufactures, published ratings. Any
materials fixtures and equipment listed which are not in accordance with the specification requirements may be
rejected, the product of any reputable manufacturer regularly engaged in the commercial production of equipment
shall not be excluded no the basis of minor differences, provided all essential requirements of this specification
relative to materials capacity and performance are met. The Contractor shall furnish a statement giving a
complete description of all points wherein the equipment proposed does not comply with the specifications.
Failure to furnish such a statement will be in turreted to mean that the equipment meets all requirement of the
specifications. Tear sheet of catalogues shall be furnished if such catalogues are not readily available to the
Engineer.
5.0
AS-BUILT/RECORD DRAWINGS
5.1
As-Built/Record Drawings and Charts for Internal Electrification.
Before the installation is finally handed over to the Employer the Contractor shall prepare and submit to
the Engineer for approval As-Built/Record drawings showing layout of all electrical fixtures and Boards
and positions and layout of conduits and exposed wiring if any and cable runs with dimensions and full
circuit details.
If the Engineer finds that the As-Built Drawings are not complete in all respects and/or they contain
errors, the Contractor shall do the corrections and resubmit to the Engineer, more than once if necessary,
till the Engineer can approve the As-Built Drawings.
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150
General Specification
A detailed circuit Chart shall be prepared, fitted in a durable frame and fixed in an approved position
adjacent to the main distribution control gear.
The installation shall not be considered complete till the As-Built Drawings free from incompleteness
and errors are submitted to and approved by the Engineer and the Charts mentioned above are fixed in a
satisfactory manner.
5.2
As-Built/Record Drawings for External Electrical Works
Before the installation is finally handed over to the Employer, the Contractor shall prepare and submit to
the Engineer for approval As-Built/Record drawings showing all routes and depths below ground of all
electrical cables, telephone cables.
If the Engineer finds that the As-Built Drawings are not complete in all respects and/or they contain
errors, the Contractor shall do the correction and resubmit to the Engineer for approval of the As-Built
Drawings, more than once if necessary, till the Engineer can approve the As-Built Drawings.
The installation shall not be considered complete till the As-Built Drawings free from incompleteness
and errors are prepared and submitted by the Contractor to the Engineer and the Charts mentioned
above are fixed in a satisfactory manner.
Submission of As-Built/Record Drawings for all work is a pre-requisite for Contractor's claim for final
payment for any work including Electrical Work.
6.0
PAINTING
Manufacturer
All paints and primers shall be made by BERGER/approved best quality)
Mending G.I. members
Galvanization spoilt by welding shall first be mended by Epilux-4 zinc-rich primer, 2 Pack, (J65).
Painting on G.I. members
Galvanized iron members (after mending galvanization spoilt by welding, if any by Epilux-4 zinc rich primer
(J65)) shall be coated with Wash primer 2 Pack, (J31) and yellow zinc chromate (J41) before the specified final
paint is applied.
G.I. Pipe Poles
The final paint shall be 2 coats of Single Pack Aluminium (J04)
G.I. Pipes and accessories Below Ground
The final paint shall be 2 coats of Epilux-5 Coal Tar Epoxy, 2 Pack, Black.
Galvanised steel boxes
If no paint is indicated, any damage to galvanization shall be repaired by Epilux-6 zinc-rich primer, 2 Pack, (J65).
DB/SDB in 16 SWG sheet steel
The final paint shall be 2 coats of Epilux-4, Enamel, 2 Pack, grey, (J33) over Epilux red oxide primer, 2 Pack,
(J42).
H.T. Panel, L.T. Panel, Power Factor Improvement Plant, Auto-Manual Change Over Panel and Auto-Mains
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151
General Specification
Failure Panel in 14 SWG galvanised sheet steel
Any damage to galvanisation in the Panel surface by welding or otherwise shall first be primer mended by
Epilux-4 zinc rich primer (J65) followed by Wash Primer, 2 Pack, (J31) and Yellow Zinc Chromate Primer (J41).
There after the final paint shall be applied in 2 coats of Epilux-4 Enamel, 2 Pack, Grey colour.
Paint on non-galvanized mild steel members
There shall be final paint of 2 coats of Epilux Enamel paint, 2 Pack (J33) over a coat of Epilux Red Oxide
primer, 2 Pack, (J42).
No Aluminium to be embedded in or to come in contact with concrete/plaster
Since the metal aluminium is affected by alkalies present in cement, no aluminium conduits or accessories or any
other aluminium body shall be embedded in concrete or used in positions where it may come in contact with
cement products such as concrete and plaster.

Standard Brick mentioned herein shall be 241x114x70mm in size and shall be first class with
150Kg/cm2 compressive strength on flat.

All sand mentioned in different items, sand to be used in mortar for brick work and plaster and sand to
be used as fine aggregate for plain concrete shall be clean and of F.M. 1.30 min.
Sand to be used as fine aggregate in R.C. shall be clean and of F.M.2.30 min.
Coarse aggregate for C.C and R.C shall be clean and be made from jhama bricks of 250 kg/sq.cm.
compressive strength and graded 19mm down.

7.0
EXCAVATING, TRENCH MAKING AND BACK FILLING
7.1
8.0
Excavating, trench making and back filling is as specified elsewhere later on.
WOODEN MEMBERS
8.1
9.0.
Cement shall conform ASTM C150 Type 1.
Wood battens, angles, boards and boxes for surface wiring shall be best quality Teak/Garzon wood.
GENERAL INSTALLATION REQUIREMENTS
9.1
Concealed Installations
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9.1.1
Where condition is shown on the drawings or is otherwise specified as being concealed, such
conduit may be embedded in structural slabs or in concrete fill laid on top of structure slabs or
concealed within hollow spaces. Where embedded in structural slabs conduits shall not exceed
30mm trade size, unless there are specific identification to the contrary. In areas where the slab
is less than 125mm thick, the overall diameter of the largest conduit shall not exceed one third
of slab thickness.
9.1.2
All the conduit running through the boxes and columns shall be laid with the innermost
reinforcement case with suitable effect in conduit so to make the outer surface of junction box
cover for switch box edges flush with the finished surface level or beam of columns as
approved.
9.1.3
Care shall be taken when making concealed installation to see that adequate clearance is
provided over the thickness elements such as coupling etc. so that fill or architectural finishes
may be applied which will be smooth, flat and not subject to spalling or cracking.
152
General Specification
9.1.4
9.2
Raceways runs embedded in slab shall be spaced not less than three outside diameter centre to
centre unless they are so coordinated with structures as not cause weakens.
Exposed Installation
9.2.1
Raceways or there wiring methods shall be exposed only :
a.
b.
c.
9.3
9.2.2
Exposed raceways of there wiring method shall be run parallel to building, walls, columns
lines etc. throughout.
9.2.3
All exposed heavy conduits are to be fastened to masonry walls, floor or partitions, use of
wooden plugs will not be permitted instead rowel plugs should be used. Metal saddles of
approved type not more than 0.61M apart shall be used for fixing exposed conduit.
Routing
9.3.1
Every effort shall be made to route raceways or wiring therein so as prevent wiring from being
subject to high ambient temperature condition. minimum clearance from heated pipes, ducts or
surface such as breathings, flush etc. shall be maintained as follows :
a.
b.
c.
d.
9.4.
9.5
Crossing un-insulated pipes or ducts
75mm
Crossing insulated pipes or ducts
25mm
Running parallel to un-insulated pipes, ducts or surface 900mm
Running parallel to un-insulated pipes, ducts or surface 150mm
9.3.2
Regarding of any routing shown on the places, raceways or other wiring method shall not run
exposed over a boiler or embedded in construction under a boiler unless special provisions for
wiring through these specific high ambient temperature areas have been indicated.
9.3.3.
Regarding or other wiring methods run in suspended ceiling may be installed as the draw, files,
except that, where such raceways etc. and being installed prior information regarding the final
layout of all trade occupying, the suspended ceiling plenum they shall be installed in
coordinated Square manner so as to minimize future conflicts.
9.3.4.
Under no condition raceways or other wiring methods be installed in elevator shafts and
hoistways. Where outlets are being provided for such items as tri cables, pit lights, run by lift
etc. only the outlet boxes themselves shall be located within the confines of the shaft.
Miscellaneous Requirements
9.4.1
The installation of raceways or other wiring methods requiring the notching, cutting or drilling
of structural elements shall coordinated with the other trades to ensure that no weakening of
the structure is caused.
9.4.2.
When finishing or snaking raceways to set up for pulling in wires and cables, fish taps with ball
types means shall be used.
Wires and cables shall not be pulled into raceways until :
9.5.1
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In specially assigned electric riser closets, shafts or switch board room.
In mechanical equipment spaces.
Where specially indicated on the drawing or otherwise with the expressed permission
of the Engineer.
a.
The project has been progressed to such a stage as to not likely to injure electrical
153
General Specification
wires or cables.
9.6.
The project has been progressed to a point where raceways are dry and moisture is
no longer likely to get into them.
c.
Wires or cables shall be pulled into raceways utilizing a suitable brush, followed by
an 85% diameter ball mended ahead of the wires or cables in the pulling assembly.
9.5.2.
The only permissible pulling lubricants is powdered soap-stones.
9.5.3
Sufficient slack shall e left on all rooms or wires and cables to permit the proper connection of
devices, equipment etc.
Mounting Height
9.6.1.
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b.
Mounting height of outlet and fixtures shall be accordance with the following list of bottom
line dimension above finished floors unless otherwise shown on drawings.
a.
Light and fan s switch broads
-
1.37M
from finish floor level on wall
b.
Wall bracket light
-
2.44M
from finish floor level on wall
c.
Socket outlet on wall
-
2.29M
from finish floor level on wall
d.
Socket outlet above the lab table
-
1.07M
from finish floor level on wall
e.
Telephone and Intercom
-
225mm
from finish floor level on wall
f.
Calling Bell outlets
-
0.76M
from finish floor level on wall
g.
Calling Bell Indicator
-
2.44M
from finish floor level on wall
h.
Electric Clock outlet
-
2.44M
from finish floor level on wall
i.
Fire Alarm outlet
-
2.44M
from finish floor level on wall
j.
Fire Alarm Bell
-
2.13M
from finish floor level on wall
k.
Ceiling Fan
-
2.60M
from finish floor level on wall
l.
Lamp for Operation Theaters
-
m.
Television Antenna outlet
-
225mm
from finish level
n.
Ceiling suspended Fluorescent Light
Fitting
-
2.60M
from finish level
To ceiling with adjustable chord to
increase the height of lamp.
154
General Specification
B.
MATERIALS AND THEIR INSTALLATION :
1.
PIPE (CONDUIT) / BATTEN WORKS
1.1.
PVC Pipe (Conduit) and Accessories
The work under this item comprises supply and installation of rigid, water grade PVC Pipe and
accessories concealed or exposed in/on floors, roof slabs, walls and column where necessary in
accordance with the drawings. PVC Pipes shall be of standard manufacture to meet the requirement of
BS 3505 : 1968 but with thickness and weight per metre relaxed as per Table - 1. Pull boxes, circular
boxes, bends, sockets, elbows etc., shall be of PVC or other similar inert synthetic materials, press fitted
and then sealed with PVC solvent cement or by any other standard glue as prescribed by the
manufacturer. Switch Boxes, and Junction Boxes shall be made of Steel 18 SWG and galvanised. Each
junction box shall have an earth block where earth continuity conductor can be connected. The circular
boxes shall be of PVC material with 19mm long hub and machine screwed cover. Pull wires, to draw
the copper conductors through conduits shall be 16 SWG and galvanized. The conduits to be concealed
in slabs shall be installed along with G.I. Pull Wire in between top and bottom bar immediately after
placement of reinforcement bar as per applicable routing shown on the drawings. Conduits shall be tied
with bars by 2 x 20 SWG G.I. Wire at 610mm c/c. Conduits over false ceiling will remain exposed. All
these non-concealed conduits are to be secured with concrete surface or timber frame by galvanized
saddle or cleats at 381mm c/c. Concealed conduits in concrete wall or column surface shall be placed
along with shuttering or form work before the concrete is poured in.
Any change in routing necessitated because of job condition shall have prior approval of the Engineer.
All such changes shall be marked on the plans as field records. Conduits in brick wall shall be installed
during construction of wall. No chiselling in masonry wall shall be allowed without prior approval.
PVC Pipes shall be bent either by using a hot box bending or by using flame. In any event bending radii
shall be 6 times pipe size but 152mm minimum. The pipe bore in the bent portion shall remain truly
circular and without reduction in diameter.
The conduit run shall be continuous throughout its length and kept straight as far as possible. It shall
have either horizontal or vertical run but shall never run at an angle. Routing of conduits in between
walls at right angle shall not be allowed.
All conduit run shall be kept at least 152mm clear of all service pipes. Where necessary it shall be
rerouted or set out to maintain the specified separation. If there arise any difficulty in fulfilling the above
condition, it shall be brought to the notice of the Engineer for solution/decision.
In installing the conduits particular care shall be taken in cutting them to the proper lengths so that the
ends will fit exactly in to the outlet boxes. After installation the open end shall be carefully plugged to
prevent intrusion of plaster, dust, moisture etc.
No inspection bends shall be used. At points where inspection is normally required steel boxes shall be
used, in 18 SWG sheet fabricated by welding and galvanised.
All conduits along with accessories required for complete installation shall be furnished and installed in
a best workmanship manner.
Measurement for payment shall be in linear metre of conduits installed in place for vertical or horizontal
run as measured from the as-built drawings.
The amount of completed and accepted work measured as provided shall be paid for at the contract
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General Specification
price, per running metre which payment shall constitute full compensation for furnishing all materials
equipment, tools and labour including storage, transportation, cutting, painting and supply of conduits
and all accessories, preparing as built drawings and providing all incidentals and consumable necessary
to complete this item of work.
TABLE - 1
Recommended specifications for
P.V.C Conduits for Electrical Cables
Nominal
size, mm
Outside dia
Basic
dimension, mm
1.2
Wall Thickness
Tolerance, mm
Minimum wall
thickness, mm
Approx.
inside dia,
mm
Tolerance, mm
13
17
 0.2
1.5
 0.2
14.0
16
21.5
 0.2
1.5
 0.2
18.5
20
26.7
 0.2
1.5
 0.2
23.8
25
33.5
 0.2
2
 0.2
29.5
30
42.3
 0.2
2
 0.2
38.2
40
48.3
 0.2
2
 0.1
44.2
50
60.3
 0.2
2.5
 0.1
55.3
60
75.3
 0.2
2.5
 0.1
70.3
75
89.0
 0.2
3.0
 0.1
82.8
100
114.3
 0.2
3.0
 0.1
108.3
152
152.4
 0.2
3.5
 0.1
110.00
Metal Conduits :
1.2.1
Metal conduits shall conform to B.S. 4568 Part-1 & Part-2, or B.S. 31:1940, and shall be in 18
SWG (minimum) thick, either solid drawn or formed round and then welded. In the latter case,
the bore shall be free from any burs. The conduits shall be black enamelled or galvanized. The
steel shall be such that when bends are formed, the conduit should not break, crack or be
deformed. Appropriate sample shall be submitted prior to installation of conduit.
1.2.2
G.I. pipes
The Galvanised Iron pipes to be used in the work shall conform to ASTM A 120-83 Standard,
welded or seamless. The diameter of pipes mentioned in the Schedule of Item are nominal
diameters. The pipes shall be coated with Zinc inside and outside by hot dip process and the
Zinc used for the coating shall be any grade of Zinc conforming to the ASTM B-6. The weight
of coating shall not be less than 550gm per square metre. Each length of the pipe shall be
tested at the mill to the Hydrostatic Test pressure and Test pressure shall be 84 kg/cm2.
The pipes shall also conform to the following tables.
The pipe and accessories shall receive paint as specified in General Notes, General,
Painting.
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156
-
General Specification
Nominal Size
diameter in mm
Outside diameter in
mm
Wall thickness
in mm
Weight in kg/M
12.7
19.1
25.4
38.1
50.8
63.5
76.2
101.6
152.4
21.3
26.7
33.4
48.3
60.3
73.0
88.9
114.3
168.3
2.77
2.87
3.38
3.68
3.91
5.16
5.49
6.02
7.11
1.26
1.68
2.50
4.05
5.43
8.62
11.28
16.06
28.23
Conduits Network of each circuit shall be completely erected before the cables are drawn-in.
The conduits run shall be continuous throughout its length, and kept straight as far as possible.
It shall run either horizontally or vertically, and never at an angle. The conduits are to be
properly tied with the re-bar at 914mm spacing using 20 SWG G.I. wire and spacers. [If the
conduits are installed exposed on wall or over false ceiling those shall be secured and clamped
with saddle mild steel flat bar 25 x 3mm at 914mm spacing using rawl plug as per direction of
the Engineer.
All conduit runs shall be kept clear of gas, air and steam conduits, and conduits of other
services and for this purpose the conduits shall be either re-routed or set out with at least
75mm separation from other conduits and electrical conduits. If there arise any difficulty in fulfilling the above condition, it shall be brought to the notice of the Engineer for
solution/decision.
Conduits installed in wall shall be placed at the time of construction of the wall. No cutting in
brick work shall be allowed without prior approval of the Engineer.
1.2.3
G.I. Bends
No inspection bends shall be used. At points where inspection is normally required steel boxes
shall be used, in minimum 18 SWG sheet fabricated by welding and galvanised.
Long radius preformed bends of same material and of required angle (22.5o, 45o, 60o and 90o)
shall be used.
G.I. conduit may be bent to required angle other than above only after obtaining express
approval of the Engineer.
The inside edges of all openings though which cables are intended to pass shall be smoothly
rounded to prevent damage to the cables
1.2.4
Junction box, Pull box, Circular box and Switch box
Junction Box and Switch Box shall be shall be of minimum 18 SWG sheet steel and
galvanised. Circular boxes, Pull Boxes and fittings shall be manufactured from unplasticized
PVC copolymer material or other suitable non-metallic material. The fittings shall be
homogenous and non-porous and shall be so designed and constructed as to have adequate
mechanical strength and be able to withstand such rough uses as may be expected during and
after installations. The inside and outside surfaces of the fittings shall be smooth, clean and
uniform and free from projections and other defects.
The interior of the fittings shall be free from obstruction which might cause abrasion of cables
or which might interfere with the ready introduction or withdrawal of cables of the maximum
size and number permitted to be enclosed by the conduit.
The inside edges of all openings, through which cables are intended to pass, shall be smoothly
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General Specification
rounded in order to prevent damage to the cable.
The minimum thickness of the Pull Boxes and Circular Boxes shall be 1.5 mm.
All Switch Boxes shall have copper earth block 10 x 10 x 10mm in size with φ5 drilled hole
and φ3 machine screws tapped for 1 thread per mm.
1.2.5
Conduit termination and fittings
At the end of a run, the conduit/G.I. pipe must terminate in a metal box, galvanised. When a
conduit is terminated in a metal box (circular boxes excepted), a smooth bore brass/PVC bush
or ring bush shall be used along with 2 brass locknuts of the following specifications :
Conduit size
in mm
Locknut
Thickness in
mm
Outside
diameter in mm
No. of threads
19.1
4.36
28.58
3
25.4
4.76
31.75
3
Bush
1.2.6
Conduit
size in mm
Outside
diameter in
mm
Length in
mm
No. of
Threads
Length of
smooth bore
at end in mm
19.1
22.22
8.73
4
1.98
25.4
28.58
10.72
5
2.78
G.I. pipe in floor
All G.I. Pipes (conduit) shall be installed having a slope of 1:100 towards the floor mounted
pull box or cable duct so that condensate or leakage water drains out easily to the pull box or
cable duct. For runs of more than one conduit in the same floor the direction of slopes of
different conduits should be decided in such a systematic manner as to ensure a uniform drain
out of the leakage. All socket joints shall be made watertight. No U-bend in floor shall be
installed. All G.I. pipe and accessories shall be painted as specified in General Notes, General
- Painting for G.I. pipe below ground.
1.3
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Conduit Installation
1.3.1
Cutting of conduits shall be done with a hacksaw in a neat manner without damage to the
conduits.
1.3.2
The ends of all conduits of shall be carefully reamed out free from burrs before installation and
after threading.
1.3.3
The ends of all conduit entering box, outlet box, cabinet etc. shall be provided with two brass
lock nuts and male/female brass bushing of required size for 31mm dia conduits and larger
ones, installed bushing shall be used.
1.3.4
if bushing are of fully insulated type, an additional lock nut shall be used inside the junction
box and cabinet before installing the bushing.
1.3.5
Conduits entering main distribution feeder pull boxes shall be provided with insulated bushing
regardless of sizes.
158
General Specification
1.4
1.3.6
Care shall be taken to see that all conduits run from a permanent and continuous ground return
back to the service ground connection point. Conduits used on system which are entirely
isolated from the light and other distribution system shall be electrically continuous and
grounded in an approved manner.
1.3.7
Where conduits terminate at equipment or location where a ground bus is provided, such as
main switch boards (or pull boxes), sub-station transformer vaults etc. grounding bushings
shall be provided for each conduits. such bushing shall be bounded to the ground bus by a 8
SWG dia (Min.) wire.
1.3.8
Conduits exposed or embedded crossing building expansion or construction joints shall be
furnished with approved brass expansion fittings and shall be provided flexible grounding
bonds by passing the fittings.
1.3.9
Wherever exterior underground conduits enter the building through sleeves or openings in
walls they shall be securely and permanently plugged by means of approved sealing
compound.
1.3.10
During installation of conduits all unfinished runs and also termination in pull boxes, cabinets
etc. shall be capped in an approved manner. Caps in cabinets etc. shall be left in place until
building is ready for installation of conductor. Paper of wood plugs shall be used for this
purposes.
1.3.11
The conduits system shall be self-ventilating type and drainage outlet shall be provided at
points in the installation where condensed moisture might cool, as per standard practice of the
electrical trade.
Joints
1.4.1
Conduits shall be coupled by means of running threads. Threadless coupling shall not be
permitted. All joints shall be made up tight.
1.4.2
Where it is impossible to turn the conduit in coupling section together a Brick stone type
coupling shall be used.
1.4.3
Where conduit is to be embedded in concrete, threads shall be coated prior to coupling or
making up with red leads.
2.
CABLE WORKS
2.1(a)
Single core cable and conductors
Single core low voltage cables and conductors shall be as per B.S. 6004, or B.S. 6346, or equivalent
VDE specifications of copper conductor and PVC insulated conductors shall have 600/1000 volt grade
of PVC insulation cables. All sizes over 2.5 mm2 shall be stranded. The cable lugs shall be of copper.
Flexible cables shall be as per B.S. 600A unless otherwise specified.
(b)
Multicore cables
Multicore low voltage cables of copper conductor shall be PVC insulated PVC sheathed non-armoured
direct burial type, termite proof, made and tested according to VDE 0472/6.65 and VDE 0472/3.69 for
this type of installation, rated voltage being 600/1000V. Cable glands shall be made of brass having
screwed locking system and sizes shall suit the cable glands.
(c)
Subscriber cables (Telephone)
The subscriber cables shall be suitable for laying underground and shall be made according to VDE
0816 of 0.6 sq.mm/0.8 sq.mm (as applicable) copper conductors, with PE (Polythene) insulated and
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General Specification
core wrapping. The cables shall be tested (20oC) at voltage not less than 500V (rms) wire to wire and
2000V (rms) wire to shield with operating voltage of 150 volts (rms), shall have minimum
insulationearch resistance (tested with min. 100V d.c.) of 5000M. ohm-km, and mutual capacitance of
not more than 50mF/km (for 0.6 sq.mm)/50mF/km (for 0.8 sq.mm).
(d)
Installation Cables (Telephone)
The installation cables shall be suitable for exposed or concealed installation, of 0.6 sq.mm copper
conductors, with PVC insulation and PVC sheath star quad formation, basic unit standing and core
wrapping. The cables shall be tested (at 20oC) for voltage not less than 500V (rms) with operating
voltage of 200 volts (rms) shall have minimum insulation resistance (tested with min. 100V d.c.) of
100m ohm-km and mutual capacitance of not more than 130V mF/km (at 800 Hz).
2.2
Cable in Conduits (G.I/PVC Conduit)
Generally, single core cable (non-sheathed) are to be installed in conduits. The conduit sizes shall be as
specified in the drawings. It shall be ensured that cables are not scratched/damaged during pulling. For
long lengths over 10m, pull boxes shall be used even if not indicated in the drawings. Cable shall not be
drawn round more than two 90o bends (or their equivalent) between drawing-in-boxes, and no single
bend shall be less than 90o. No cable pulling lubricant other than powdered soap stones shall be used
and that after obtaining approval of the Engineer.
2.2.1
Cable bending radii
The internal radius of every bend in a cable shall not be less than the appropriate value stated
below:
Insulation
Finish
Overall Diameter
Rubber or PVC
(Circular copper or
circular stranded
conductors)
Non-armoured
Not exceeding 10mm
3
Exceeding 10mm but
not exceeding 25mm
4
Exceeding 25mm
6
Armoured
Any
6
Armoured or
non-armoured
Any
8
PVC (solid aluminium
or shaped copper
conductors)
2.2.2
Factor to be applied to
overall diameter of cable
to determining minimum
internal radius of bend
Cable termination and joints
No termination or joints of cables shall be allowed except at switch boxes. Termination of
cables upto 2.5mm2 shall be done by making a hook at the end, and for higher sizes, brass
cable terminals shall be used. Tee-off joints in the cable to lighting point, switches etc. shall
not be made. Looping in system of wiring shall be followed and the joints shall be made in the
switch boards only. All PVC cables shall be terminated using brass cable glands of proper size.
2.2.3.
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160
General Specification
2.3
a)
The maximum number of conductors in any conduit shall be as per drawing
conforming with the regulations of I.E.E. No joints in the conductor will be made
throughout the installation and looping system shall be followed.
b)
The conductor shall be tested for continuity and insulation before energizing and
conform to the standard laid down by the local Engineering Authority and Institution
of Electrical Engineer (England).
c)
Generally, single core cable (non-sheathed) are to be installed in metal conduits. The
conduits sizes shall be as specified in the drawings. It must be ensured that the cables
are not damaged during pulling. For long lengths, pull boxes must be used even if not
indicated in the drawing Cables shall not be drawn round more than two 900 bend
between drawing-in-boxes and any single bend must not be less than 900
d)
The cable up to 0.0258cm2 shall be solid conductor and therefore, jointing are to be
done through porcelain connector and the connection shall be wound with PIB tape
before placing in the boxes. Termination of cable termination must be used. Tee-off
joints in the cable to light point, switches etc. should not be made Looping in system
of wiring is to be followed for recessed and surface wiring and the joints are to be
made in the switch boards only. Ass 3 to 4 core PVC cable shall be terminated using
brass cable glands of proper size.
Connection to switches
The phase wire shall be connected to the switches and the neutral wire shall be kept solid in all switch
connections.
2.4
Cable colour
Cables used shall have colour as stated below :
Two wire single phase a.c. system
Red, white or blue for phase line or switch wire, black for neutral and green for earth when flexible
cords are used.
Three wire two phase a.c. system
Red for one phase.
Black for common return.
White for other phase.
Three or four wire three phase a.c. system
Red for first phase
White for second phase
Blue for third phase
Black for neutral
Two wire d.c. system
Red for positive or switch wire
Black for negative.
For two wire final sub-circuits, whether a.c. or d.c. supplying lighting or power circuits, the neutral or
"middle" wire shall always be black, and the phase or outer wire (no matter which phase it is connected
to) shall always be red. For lighting, the red wire shall always feed the switch, and a red wire shall
always be used from the switch to the light.
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General Specification
2.5
Filled-in Trenches for laying cables
The size of cable trench shall be minimum 915mm in depth and 457mm in width for each cable to be
laid. Where more than one cable is to be laid, the width is to be increased by 152mm for each extra
cable. Trench digging shall not commence until all cables are procured and brought to site store.
Excavation of trench bed may require shuttering and shoring of trench sides, bailing out water, and the
trench bed shall be dressed, cleaned and levelled. This shall be followed by 152mm thick cushioning by
sand of min. F.M. 1.0 in the bed over which the cables will be laid. After laying of cables first class
bricks shall be placed as separators between the cables. Thereafter sand filling shall be done with sand
of F.M. 1.0 upto 152mm over the top of the largest cable in the trench after which two layers of flat
brick is to be placed along the length and breadth of the trench as a mechanical protection against injury
and as a signal that a power cable is laid under the bricks.
No covering of cable trenches shall however be done before inspection and approval by the Engineer. If
the Engineer notices any damage to the cable or any other fault which requires remedy or replacement
of the cable the Contractor shall do the needful promptly at his own cost.
The rest of the trench shall be filled with earth, watered and rammed in 152mm layers. After installation
of the cables, original ground conditions are to be restored, be it brick pavement, drains, concrete road
or any other construction. All costs involved in mending good of the damages shall be fully borne by the
Contractor.
The Cables are to be placed in trenches with slight curve so that it can give way when the earth settles
later on.
Cables shall be laid into or out of the ground through PVC/RCC/G.I. Pipe of appropriate size decided
by the Engineer. The length of the pipe over the ground shall be 1.2m.
The cable route should be as direct as possible and must receive Engineer's approval before excavation.
All cable runs shall be kept at least 610mm clear of gas, sewer, water and other services pipes in
horizontal plane. Where necessary the cable run shall be re-routed to maintain the specified gap.
Trenches for H.T. Cables shall be maintained at a minimum 610mm clear distance from an adjacent
L.T. cable trench.
All cable bends shall have a radius of not less than 24 times the overall diameter of the cable for
armoured cables, and 20 times the diameter for non-armoured cables. But the radius shall not be less
than twice the diameter of the cable drum in any case.
Great care shall be exercised to avoid damage during handling of the cables and to prevent formation of
"Kinks". The cable drums shall preferably be conveyed on wheeled cable-drum carriers and unrolled
and laid directly from the drum carrier along the trench over rollers of approved construction. Carriage
by trailers or trucks can be allowed if proper care is taken during unloading the drums and unrolling is
done after placing the drum on jacks and spindles. Dragging the cables over the surface of earth along
the trench shall not be allowed. The cables should be carried and unrolled in the direction indicated on
the drums by the manufacturers.
The cables shall be terminated at required locations and as directed by the Engineer.
152mm dia G.I. pipe (or other size approved by the Engineer for L.T. cables) shall be provided for all
road and drain crossings. These pipes shall be laid direct in the ground without any sand bed, sand layer,
brick, or cable covers.
When trenches are left open overnight and where road is to be cut, the Contractor shall exhibit suitable
danger signals such as banners, red flags and red lamps at his own cost. Temporary arrangement by
placing wooden sleepers/sheet steel etc. across the road cutting for vehicular traffic are also to be made
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General Specification
by the Contractor at his own cost. The Contractor shall be wholly responsible for any accident which
may occur due to his negligence.
G.I. pipes of appropriate size and length shall be used to protect the cable from all sorts of mechanical
injury, every time it climbs up/down the pole/steel structure. Cable terminals of appropriate type, size
and capacity shall be used every time outdoor termination of cable is followed/preceded by bare
overhead lines/Bus-bars/Terminals etc.
All surplus earth shall be removed to the indicated places by the Contractor at his own cost.
Any damage done by the Contractor to any other agencies during or as a result of cable laying
operations shall be made good by the Contractor.
2.6.
Cable in G.I. or R.C pipes in Road and Drain crossing
G.I. pipes/R.C. pipes whatever is applicable and as directed by the Engineer shall be provided for all
road and drain crossing. These pipes shall be laid direct in the ground without any sand bed, sand layer,
brick or cable covers.
Cables shall laid out of or laid into the ground through G.I. pipe of suitable size as decided by the
Engineer. The length of the pipes over the ground shall not be less than 1.2m and no extra cost shall be
paid for such pipes. The exposed end of the pipes shall be sealed using PVC or wooden plugs.
2.7.
Cable works
2.7.1
Cable Boxes
2.7.1.1 All types of cable and boxes shall be of cast iron and shall comply with latest
Bangladesh Government Specification and as per drawing. All other accessories shall
be approved type and design and shall be approved by the Engineer.
2.7.1.2 The excavation shall be 1.06M deep and 0.46M wide. The bed surface shall be free
from any point sharp materials, Breadth of the trench shall be increased by 0.61M on
a joint point.
2.8
Crossing road, pavement, culvert etc.
In crossing road or pavement, a hume pipe of suitable size shall be provided in the trench shall be
covered with pre-cast slabs or blocks of sufficient strength to withstand the load over them.
2.9
Joint Cable
2.9.1
While laying the cable it shall be so arranged that cables to be jointed overlap each other by
about 0.46M to provide ample length for jointing. Metal serving and armouring shall be
removed from both cable to conform to the dimension of the box. The lead sheath (if there by
any) is than to be cut off from both cables to box dimension. The belt paper shall be removed
to within 25mm of the lead sheathing at each and exposing the insulated core. The insulation
shall be removed to the required length. All points shall be sweathed, wiped clean and properly
insulated.
2.9.2
At least 25mm clearance shall be allowed between the center of each pair or joints. A wad of
impregnated tape shall be provided between each core and in tee joints, the armouring shall be
properly bound and the box shall be replaced in the filling holes. Necessary tapping up shall be
carried out after the compound has cooled.
Cables are to be terminated with the cable glands or end box as the case may be with the cable
lugs of appropriate size and ratings.
Markers shall be provided along the cable routes at each turning point of the trench.
Markers shall be made of 3.125mm thick M.S. sheet welded to M.S. angle as shown in the
2.9.3
2.9.4
2.9.5
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General Specification
drawing or shall be made of cast iron.
3.
FEEDERS, LIGHTING AND APPLIANCE CIRCUITRY
3.1.
Sizing and other pertinent data regarding main feeders, sub-feeders, branch feeders, operation at 600
Volts or less and any branch circuitry protected by different ratings, circuit breakers are fully delineated
on the plans. All such feeders and circuitry shall be provided in accordance with the indication on the
plan and shall be connected for correct phase sequence and proper operation of the equipment served.
3.2.
Each individual lap off a feeders which is called with multiple cables per phase shall be arranged so that
all of the feeders are connected to the corresponding phase leg of the individual tap.
3.3.
General circuitry operating at less than 600 Volts. and called for or indicated without specific details as
to sizing etc., shall be understood to be lighting or less.
3.4.
Where lighting and appliance outlets are shown on the drawings without fully delineated circuitry such
shall be provided in accordance with the Ground Rules listed below.
3.5.
All lighting and appliance branch circuitry protected as 20 amp. or less shall be performed in
accordance with the following ground rules unless there are specific indications to the contrary.
3.6.
Unless otherwise noted minimum conductor size shall be No. 16 SWG dia copper.
3.7.
Conductors for circuitry operating in the range of 230 to 250 Volts. to neutral and extending in excess
of 61M from the point of supply to the last outlet or fixture tap, shall be No. 10 SWG dia copper
throughout.
3.8.
Raceway sizes shall be adequate for the number of conductors contained as required by code.
3.9.
Unless otherwise noted, circuitry shall be multi-wise utilizing common neutrals arranged so that no
neutral conductor acts as common wire more than one circuit conductor connected to the same phase leg
of the supply system.
3.10.
Circuit shall be balanced on phases at supply point as evenly as possible.
3.11.
Except as hereinafter differently specified standard type of metallic outlet box shall be provided for each
and every wiring device, lighting fixtures etc.
3.12.
Where more than one switch is shown on the plans or a single location their switches shall be gangmounted to a single suitable outlet box.
3.13.
A switch and receptacle shall not be gang-mounted in a single outlet box unless the plans specifically
indicate such a communication.
3.14
Where buried-in-outlet boxes are required by code authorities to separate wiring devices wired off
different phase legs of the supply system, to separate wiring of different voltage system or for other
reasons, such barriers shall be provided at no additional cost.
3.15.
Under no condition shall any switch break any neutral conductor.
3.16.
Outlet boxes for switches shall be located at the strike side of doors, door swing indicated on plans are
subject to field change. Outlet boxes for switches shall be located on the basis of the final door swing
arrangement.
3.17.
Unless made accessibly by other means, boxes for recessed ceiling fixture be mounted near to the
ceiling fixture.
3.18.
Final connection from outlet boxes to recessed ceiling fixtures shall be means of suitable flexible
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General Specification
fixtures pigtails not less than 1.22M and not more than 1.83M long. In all cases enough slack shall be
left in pig-tails to permit removal of fixtures from ceiling for inspection with disconnection.
3.19.
Where the specifications for drawing indicates no specific requirements as to the loading or connections
of outlets in lighting and appliance branch circuit, the following maximum limitations shall be follows :
No more that 12 outlets of 1650 watts shall be applied to any single 10 amps circuit and no more than
24 outlets of 400 total watts to any single 20 amps circuit in the range of 230 to 250 volt to neutral.
4.
3.20.
At any location where lighting and appliance branch circuitry is provided extending from a flush
mounted panel board to a suspended ceiling immediately above, at least 4 (four) 25mm empty conduit
shall be provided (in addition those required for active circuitry) to permit future wiring
3.21.
Emergency wiring shall be run in a completely separate raceway conduit system containing no wires of
" Normal" lighting and appliance.
EARTH CONTINUITY CONDUCTOR WORKS
The Conductor shall be electrolytic copper of 100% conductivity at 20oC (68o F) (International Annealed Copper
standard) with weight resistivity of 0.15328 ohm-gram per sq.m. at 20oC (68o F) and density of 8,890 kg/m3 for
meeting the requirements of B.S. 636 : 1969 or its metric adoption.
The earth continuity conductor and earthing lead shall run in accordance with the drawings and direction, and
all metal fittings shall be earthed with earth continuity conductors. All the earth continuity conductors from the
various circuits, sockets, etc. shall be connected to the earthing block located near the DB/SDB. The earth
continuity conductors shall be of sizes as stated in the drawings. All DB/SDB/SB shall be interconnected with
earth continuity conductors. The earth continuity conductors shall be drawn along with the cables and no joint
shall be allowed from earthing block to the respective earth point. Light and fan points, excepts where indicated
other-wise, shall not be earthed.
5.
LIGHT FITTINGS AND FIXTURES
The light fittings shall be constructed as per schedule, and shall comply with the relevant requirements of
applicable B.S. including B.S. 4533.
The chokes, if applicable, shall comply with the requirements of B.S. 2818, and shall be Thorn, or of equivalent
quality and shall have appropriate power factor correction capacitor (250V 3.5MF for 20W and 40W tubes,
5MF for 65W tubes, and 7MF for 80W tubes if used with Thorn chokes : for other chokes of approved best
quality, the improved p.f. shall not be less than 0.90).
The starters for fluorescent lights shall be 91W lamp type and shall have built in radio interference suppressor
capacitor.
All incandescent light fittings, except where specifically stated other wise, shall have un-switched brass holders
for BS 22/25/26 lamp caps complying with B.S. 52 : 1963.
Fixtures near combustible materials shall be so constructed or installed, or equipped with shades or guards that
combustible materials shall not be subjected to temperature in excess of 90oc.
Appropriate samples of light fittings with chokes and starters shall be submitted prior to installation.
The light fittings shall be installed in accordance with the applicable fittings layout drawings.
All pendant fittings shall be supported from brass ceiling base plate with at least 9.52mm screw-hub.
The location of outlets shown on diagrammatic wiring plans shall be considered as approximate and it shall be
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General Specification
incumbent upon the Contractor, before installation of outlet boxes, to study all pertinent drawings and obtain
precise information from the architectural schedule, scale drawings, large scale and full size details of finished
rooms and approved shop drawings of other trades. It shall be understood that any outlets may be relocated at a
distance not exceeding 4.57m from the location shown in the drawings. In centering outlets, due allowance shall
be made for overhead piping ducts, window and door trim, variations in thickness of furring, plastering etc. as
erected, regardless of whatever is shown on small scale drawings. Outlets incorrectly located shall be properly
relocated at the Contractor's own cost.
6.
FANS
Materials, assembly and performance shall conform to BSTI standard. Appropriate samples shall be submitted
prior to installation of the fans and fan clamps.
6.1
Fan Hook
The U-type fan hook shall be made of 15.87mm dia mild steel rod as per drawings.
6.2
Ceiling Fan
Ceiling fans shall be of capacitor type, A.C. 240V, single phase 50 Hz, complete with suspension rod of
required length, canopy and shall be constructed in accordance with applicable B.S.
The ceiling fan shall be of "Brand and Make" shown in schedule of Items.
6.3
Wall Mounted/Pedestal/Exhaust Fan
The Wall Mounted/Pedestal/Exhaust Fan shall be as per schedule and shall be constructed in
accordance with applicable B.S.
The fan hook shall be provided during slab casting as per schedule. The fan hook shall be secured in
place during the casting.
The fan shall be installed in accordance with the applicable fan layout drawings. Circular box with
ceiling rose for fan outlet shall be at the centre of the clamps, as detailed in the drawings.
Fans shall have the following installation height except where indicated otherwise :



7.
Ceiling fan bottom
Exhaust fans
(top edge of fan i/c cover)
Wall fan blade end
:
2.58m from the floor
:
:
As close to ceiling as possible
2.58m from the floor.
DISTRIBUTION BOARD/SUB-DISTRIBUTION BOARD
7.1
DB/SDB Boxes
The DB/SDB Double door boxes shall be as per schedule and shall be safety dead front fixed type
having circuit breakers and shall be designed for operation on a 240/415V, 50 Hz, 3 phase, 4 wire
system. The panels shall have the phases clearly marked and where required shall have solid neutral
buses. The panels shall be constructed with 16 SWG mild steel sheets as per schedule and shall comply
with relevant requirements of applicable B.S. including: B.S. 4649, where applicable with standard
concentric knockout of required size all around. The Boards shall be painted as per General Notes,
General, Painting. The colour of paint shall be as decided by the Engineer. The panels shall be mounted
directly on frames. The door is to be provided with flush lock and handle. All doors are to be keyed
alike. All hinges shall be concealed.
7.2
Bus-Bar
Bus-Bar shall be of the laminated type, constructed of hard rolled copper each part being finished fitted
and bolted together using electroplated steel bolts for assembling. Bus-Bars shall be constructed on the
basis of 1.24 Amp per sq.m. cross section metal bars which shall have same width as outside lugs.
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General Specification
O
Spacing
The minimum distance bars, metal parts, bus-bar, etc. shall not be less than what is specified
below :
Opposite polarity where mounted
in the same surface
7.3
Opposite polarity where
held free in air
Not over 250V 31.75mm
19.05mm
Not over 600V 50.80mm
25.40mm
Live parts to ground
12.7mm
Conductors and bus-bars shall be located as to be free from physical damage and shall be held firmly in
place. The arrangement of bus-bars and conductors shall be such as to avoid overheating due to
inductive effects.
The Board shall be installed in accordance with applicable layout drawings. Minimum height to bottom
of the Boards from the floor level shall be 610mm maximum height of any circuit breaker/switch shall
be 1.83m from the floor level.
The location of DB/SDB shown on diagrammatic wiring plans shall be considered as approximate and it
shall be incumbent upon the Contractor, before installation of DB/SDB to study all pertinent drawings
and obtain precise information from the architectural schedule, scale drawings large scale and full size
details of finished rooms and approved shop drawings of other trades. It shall be understood that
DB/SDB may be located at a distance not exceeding 40cm from the location shown on the drawings. In
centering DB/SDB due allowance shall be made for piping, ducts, window and door trim, variations in
thickness of furring, plastering etc. as erected, regardless of whatever is shown on small scale drawings,
DB/SDB located incorrectly shall be properly relocated at Contractor's own cost.
7.4
Meter Board
All meters and cut outs are of ratings given in schedule fixed in 16 SWG sheet steel box with locking
arrangement The box must be hammer painted. The materials shall be submitted to the
Authority/Engineer..
8.
CEILING ROSE
The ceiling rose shall be moulded plastic of approved best quality.
Wherever the ceiling rose shall be used it shall be installed as near as possible to the fittings. For ceiling fans,
these shall be installed at the centre of the hook.
9.
MCB/MCCB
The MCB/MCCB shall be quick-make, quick-break type, and shall have inverse time limit characteristics with
instantaneous magnetic trip elements functioning on overloads over the normal operating range. All circuit
breakers shall be 'trip-free'. Ratings and frame sizes of breakers shall be in accordance with schedule. All lugs
must be of the solderless mechanical type. The MCB must comply with B.S. 3871 : Part-1 (1965) category M4
(5A-60A). Rated voltage 240/415V A.C. 50 Hz, interrupting capacity 4000 amp, capable of providing overload
and short circuit protection, through thermal magnetic trip actions respectively : temperature rating, 40oC
tropicalized (moisture-fungus corrosion treated), with contacts of silver alloy : terminal capability upto 70 mm2
wire.
The breakers shall be designed manufactured and tested in accordance with B.S. 3871 part-2 or equivalent having
the following short circuit rating with overload and short circuit protection with thermal and magnetic tripping
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General Specification
action and temperature rating 40o C, tropicalized (moisture fungus corrosion treated) termination capability upto
the requirement :
5A
5A
10A
80A to
200A
400A
600A
10.
to
to
100A
to
to
to
60A
SP
TP
70A TP
TP
14KA
300A TP
500A TP
1200A TP
4KA SYM at 230V
5KA SYM at 480V
10KA SYM at 480V
SYM at 480V A.C.
30KA SYM at 480V
42KA SYM at 480V
85KA SYM at 480V
A.C.
A.C.
A.C.
A.C.
A.C.
A.C.
SWITCH WORKS
The flushed snap plate/grid switches shall be vertical single pole (1-way/2-way) 5A A.C. architrave rocker
operated switches white in colour, to B.S. 3676: 1963, complying with the test requirements for inductive,
fluorescent or resistive loads specified, and satisfy the best requirements for three types in fluorescent lamp
circuit, upto the ratings of these switches as set out in B.S. 3676 amendment 3, 1969. The switches shall have
minimum clearance of 3mm between the contacts, and a similar minimum creepage distance. Flush dimmer
switch/Fan speed controller white in colour to BS5518: 1977 & BS800 : 1977 or relevant IEC standard
complying with test requirement for induction or resistive load specified. All contacts shall be faced with pure
silver/silver-cadmium oxide alloy. The switch operating member shall pivot independently of the rocker, making
the speed of `make and break' independent of the speed at which the rocker is operated. Terminal capability :
minimum 2 x 2.5 mm2 conductors for each. Appropriate samples shall be submitted prior to installation of
switches.
Switches shall be installed on switch board or otherwise as per drawings.
11.
SWITCH BOARD/DIMMER/FAN SPEED CONTROLLER BOARD WORKS
Switch boards and/or fan dimmer boards shall be as per schedule and shall have plate switches and/or fan
dimmer. Switch boards shall have copper earthing block of appropriate size.
The switch boards and fan dimmer boards shall be installed on wall at a height of 1372mm from the floor if not
specified otherwise, and at locations shown in applicable layout drawings.
The phase wire shall be connected to the switches and the neutral wire shall be kept solid in all switch
connections. The earth continuity conductor (ECC) shall be connected to the earth point inside the switch board.
The approved size galvanised steel boxes shall be installed at the time of construction of the wall to avoid chasing
in wall.
The location of board shown in diagrammatic wiring plans shall be considered as approximate and it shall be
incumbent upon the Contractor, before installation of switch board/regulator board boxes, to study all pertinent
drawings and obtain precise information from the architectural schedules, scale drawings, large scale and full size
details of finished rooms and approved shop drawings of other trades. It shall be understood that any outlet may
be relocated at a distance not exceeding 4.5M from the location shown in the drawings. In earthing outlets, due
allowance shall be made for piping, ducts, window and door trim, variations in thickness of furring, plastering,
etc. as erected, regardless of whatever is shown on small scale drawings.Switch boards & other boards located
incorrectly shall be properly relocated at Contractor's own cost.
12.
EBONITE/ACRYLIC/FORMICA SHEET
(i)
Ebonite Sheet
Paper impregnated and press fitted soacked with insulating oil from the Ebonite sheet to be used for
switch board, DB/SDB cover. It is a Electrical insulating material and have heat insistent quality.
Available in market in Down, Deep brown and bitter chokolate colour leaving different thickness. For
switch board 3mm thick sheet will serve the purpose.
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General Specification
(ii)
Acrylic Sheet
Polyvinyl base plastic sheet is available in market in trade name of Acrylic sheet. It can also be used for
switch board cover. It is got no insulating on heat resisting quality but available in different thickness
and different colour. For switch board 3mm thick sheet with same the purpose and beauty.
(iii)
Formica Sheet
The Formica sheet shall be 3mm thick of approved colour shall be installed on switch board on
otherwise mentioned. It has got heat resisting quality.
13.
SWITCH SOCKET - OUTLETS (ROUND PIN)
All switch socket outlets, except the shaver sockets, shall be round pin type, white in colour, conforming to B.S.
5733:1979 or relevant IEC Standard. All mouldings shall be made from aminoplastic urea moulding powers to
B.S. 1322: 1950 and shall possess high scratch resisting qualities. These shall be supplied with counter sunk
cadmium plate fixing screws and mounted in 18 SWG galvanised sheet steel shall be painted as per General
Notes, General, -Painting, having brass earth point as per drawings and direction.
The socket/MCB/MCCB shall be installed on wall with lower end of the face plates at height and locations
shown in applicable layout drawings.
The fixing of the units on the outlets boxes shall be by means of flat head cadmium plated screws. The flat head
of the screw shall be sunk in the plates so as to finish flush with the surface of the cover. The mounting heights of
the outlets shall be as shown in the drawings. The earth wire shall be connected to earth point of the boxes of the
3rd pole of the 3-pin sockets, 2-pin socket outlets are for television, shavers, calculator etc.
14.
CALLING BELL
Electrical calling bell should be of Bugger on Ding Dong sound type. The working voltage of the bell coil will be
240V A.C. The body of the Bell should be of plastic on Acrylic. Separate Board of plastic sheet with brass holder
and 40W Electric bell would be used in service with the Bell. Separate calling Bell push are to be used on board
as per drawing.
15.
EARTHING DEVICE
(i)
Earth electrode
The pipe earthing electrode shall be buried below ground level, as per schedule by tube-well sinking
method. The earthing lead from the DB to the main earthing electrode shall be installed in G.I. pipe of
specified diameter. The terminal connected to the earthing electrode shall use a copper clamp of
203x38x6.35mm size for making the connection.
a)
Pipe Electrode (where applicable)
The earthing inspection pit shall be constructed as per schedule and direction. The pit shall
have well formed regular sides. Curing for the R.C, shall be for 4 weeks, and for C.C., brick
work and plaster shall be 2 weeks.
(ii)
Earthing Lead
Earthing lead shall consist of copper conductor as per schedule. All terminal lugs shall be of solderless
mechanical type of tinned copper and nut-bolts of brass.
The earthing leads from the earth electrode shall be connected to the brass bar of test point. A double
run of specified tinned copper conductor shall be brought out as earth lead for the earth electrode
through G.I. pipe from the electrode and connected to the brass bar. There shall no joint in the copper
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General Specification
earth lead. All earthing lead shall follow the shortest and most direct route to earth electrodes and sharp
bends and joints shall be avoided. The earthing leads shall be connected to the earth electrode as per
drawings. The joints shall be made mechanically strong and electrically continuous with minimum of
resistance.
Earthing lead shall consist of copper conductor as per specification given in Art 2.03a. All terminal lugs
shall be of copper and nut-bolts of brass.
(iii)
Earthing Block
The earthing block shall be of solid electrolytic copper, cast and machined, of size as per schedule
having at least 10mm dia drilled, holes for accommodating the terminals of the earth continuity
conductor. Requisite number of brass nuts and bolts shall also be provided.
(iv)
Earth Inspection Pit
Bricks used shall be 1st class. Only approved best quality cement shall be used. Jhama brick khoa for
R.C.C. cover shall be 25mm down graded (upto 6mm) and shall be washed clean before casting, 8mm
dia M.S. rod @ 25mm c/c, with two 9.5mm dia, M.S. hook (of 50mm diameter) shall be provided in the
cover slab.
(v)
Earth Loop Resistance
The maximum earth loop resistance from any point in the installation including earthing lead to the
earthing electrode shall not exceed the resistance specified in the schedule, or that indicated by the
Engineer. The Contractor shall ensure that the leads are efficiently bonded to all metal works other than
the current carrying parts, so that the above resistance level is not exceeded. It will be the duty of the
Contractor to provide earth tester for test of installation in presence of the authorised representative of
the Engineer, and submit earth test report to the Engineer for approval.
16.
LIGHTNING PROTECTION
16.1
Air-Terminals
Air-terminals shall be of copper of grade required for commercial electrical work, generally designated
as being of 98 percent conductivity when annealed. The size and shape of the air-terminal shall be as per
drawings and schedule.
Air-terminals shall be clamped with the building as per drawings and in manner that there is no
possibility of overturning. Where necessary, additional braces, permanently and rigidly attached with
the building, shall be used. On mortar and brick work, all holes shall be made with proper tools, such as
a Rawl bits, and shall be made in brick rather than in the mortar joint.
All air-terminals shall be installed in a manner to bring the tip not less than 300mm above the object to
be protected.
16.2
Roof Conductor
Roof conductors shall be made of copper of grade as specified in Art. 12.
Roof conductors shall be continuous and without any joint between terminations. All terminations shall
be permanent, both electrically and mechanically. Where jointing in a conductor is absolutely
unavoidable it shall be made after express consent of the Engineer. The joint shall be mechanically
strong and well made and provide adequate electrical conductivity, which shall be secured by a contact
area not less than double the conducting cross-sectional area of the conductor.
No bend in the conductor shall have a radius of less than 200mm and the angle of any turn shall not be
D:\533561914.doc
170
General Specification
less than 90. All conductor runs shall preserve a downward or horizontal course.
The conductor shall be securely attached to the building by means of fasteners at intervals not exceeding
1.2m, and shall be embedded under roof finish or concealed in plaster. Fasteners shall have cross
section not less than 14 SWG and shall be made of copper.
16.3
Down Conductor
The down conductor shall be continuous and shall be installed as indicated in the schedule.
16.4
Test Point
The test point shall be made as per schedule and drawings. The brass bar assembly shall be well-formed
and shall be without filling. The conductor terminals shall be provided with tinned copper lugs of size as
detailed in the drawings.
The test point shall be installed during construction of the building wall and made flush with the outside
walls finish.
Copper lugs shall be press-fitted with the conductor terminals with crimping tools, or shall use cast brass
lug-block with brass nuts. The lug shall be bolted with the brass-bar by means of brass nuts and bolts.
17.
TELEPHONE SYSTEM
17.1
The telephone installation includes the following items.
17.1.1
Supply and installation of telephone conduit system pullout boxes, covers for telephone outlet boxes,
junction boxes, junction boxes and cabinets as previously stated for electric system.
17.1.2
The jumper stand in PBX Rectifier, Telephone exchange equipment telephone instrument will be
supplied and installed by T & P Department.
17.1.3
All the outlet and pullout boxes shall be as in Electrical system and should be designed in such a way
that any pull-out may be converted into outlet box, simply by replacing its brass cover with the flat or
dome shaped cover or the outlet box as per drawings and vice versa and therefore all the covers shall be
inter changeable.
17.1.4
The earth continuity shall be maintained throughout the telephone installation. An earth terminal in the
pull-out box shall be used to feed earth continuity to telephone instrument The earth continuity wire will
be 12SWG dia HDBC.
17.1.5
Telephone Grommet
The telephone grommet shall be constructed as per schedule, of 18 SWG sheet steel and shall comply
with the relevant requirements of applicable B.S.
17.1.6
Telephone Plug
Telephone plug shall be made of brass, nickel plated, with tubular insulation and solder terminals. It
shall be tested at 1000V A.C. and shall fit all standard telephone jacks.
17.1.7
Telephone Jack
The jack shall be made of brass, nickel plated, with nickel plated bushing, backelite insulation, brass
hexagonal nut and steel mounting washer.
17.2
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Telephone Junction Cabinet (Main)
171
General Specification
18.
19.
17.2.1
The junction cabinet shall be metal clad, made of safety dead front, free standing on floor, fixed type
cubical designed with hinged door, built in concealed type, easy access, services and replacement. It will
be surface mounted made of heavy 16SWG thick steel sheet metal with standard concentric knock-outs
all around suitable places. The doors of the cabinets shall be keyed alike.
17.2.2
The cabinet shall be proofed against ingress of vermin. The cabinet shall be designed to accommodate
connecting terminals with indicating and marking arrangement. It shall be equipped with terminals as
shown in the schedule of quantities.
17.2.3
The cabinets shall be equipped with PVC mounded terminal strip with the screwed type terminals. The
terminals and screws shall be made of brass and dull chrome plated in accordance with those used by T
& P Department, Government of Bangladesh.
17.3.
Telephone Sub-Junction Boxes.
17.3.1
The junction boxes shall be in accordance with the specification hereof with the following operations:
The junction boxes shall be suitable for concealed or surface mounting on walls and shall be
made vermin and dust proof.
b.
These junction boxes shall be suitable to accommodate the connecting terminals as shown on
the drawings and in schedule of quantities, with the indicating and marking arrangement for
cable connections.
Danger Plate
18.1.
The danger plate shall be displayed in each pole with red pattering on white back ground. The lettering
shall be in English and Bengali stating " DANGER", "CAUTION" and " PRESSURE".
18.2.
The size of the plate will be 250mm x 150mm x 3.175mm of M.S. plate and the size of letter will be
38mm in height.
18.3.
Non - Climbing Device
18.4
18.5.
Non - climbing device of flat iron bar welded with ring from spike as per drawing shall be in each pole.
Barbed wire device may also be used covering 50mm space of the pole as per direction of the
EMPLOYER/ CONSULTANT.
Guard Wires
19.1
20.
a.
Safety device, cradle guards or other approved method shall be provided in crossing of the aerial line
against the possibility of coming into contract with each other and so that no broken wire can fall dead.
The guard wires or the cradle shall be of the size so that it can carry the weight of the broken line and
withstand the mechanical pressure of the fallen wires.
Fluorescent, Mercury Lamps, etc
20.1
All discharge lamp (fluorescent, mercury, etc.) lighting fixtures furnished as part of the electrical work
shall conform to the following and the fittings shall be suitable to operate on the main particulars of
which are given below.
a.
b.
c.
d.
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Number of Phase - Single phase
Voltage
- 230 Volts  5%
Frequency
- 50c/s.
Type
- Alternating current.
172
General Specification
21.
20.2
The fluorescent lamp shall be high power factor operation, tubular in shape for general lighting service.
20.3
The colour shall be day light.
20.4
Ballast and capacitor shall be rigidly mounted to the inside of the top of the fixture housing with ballast
surface and housing in complete contract for efficient conduction of ballast heat, Ballast mounting shall
be permanently affixed to the housing.
20.5
The diffusers shall be glare free, moulded out of 3.175mm thick opal materials of uniform density and
sturdy construction. The diffusers shall be quick detachable type and shall be supplied as asked for in
the schedule of quantities.
Incandescent Lamp :
All incandescent lamp lighting fixtures furnished as part of electrical work shall conform to the followings.
21.1
Sockets shall be suitable for the specified lamps and so that lamps are positions in optically correct
relation to lenses, reflector, baffles, etc.
21.2
Face plates of incandescent recessed fixtures which also serve as a ceiling trim, shall be gasket and
drawn up to the ceiling as might be necessary to ensure complete contact of the face plate with ceiling
surrounding the fixtures.
21.3
All lenses, louvers or other light diffusing elements contained in fixtures frame shall be removable but
positively held within the frame sot that the hanging motion of the frame will not cause the diffusing
elements to drop down.
21.4
All glass elements, lenses, diffusers etc. shall be made of thermos pane materials or approved best
quality in characteristic to that of pyrex.
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General Specification
SPECIFICATIONS FOR SUB-STATION EQUIPMENT
General Specifications
The specifications for Sub-station Equipment mentioned below cover design, manufacture, assembly, supply, delivery,
installation, testing and commissioning of the sub-station equipment at site.
Climatic Conditions.
The climate in Dhaka is tropical and has marked Monsoon character with seasonal changes from humid, warm, in rainy
season, to cool and dry in winters. Maximum temperature occurs during the period from April to August reaching
approximately 43 Deg. C (110 Deg. F). with a relative air humidity of 70% to 95%
The annual mean temperature is approximately 29 Deg. C(84 Deg. F) During the rainy monsoon months from June to
September, the average relative air humidity is 80% and reaches extreme values upto saturation point during rainy
periods. The annual rainfall, most of which occurs in the period June to September is 2000mm to 2500mm.
Operating Conditions
The sub-station equipment will be connected to source of power supply of the 11kv, 3-phase, 50Hz, Bus of Electric
Supply Authority (PDB/REB/DPDC).
Standards
All equipment and materials shall be in conformity with the most recent relevant Bangladeshi laws, standard and rules and
regulations particularly the Electricity Act. All equipment and materials to be supplied, require approval by the
Government of Bangladesh or its legally constituted Local Authority and must satisfactorily pass all inspection and test
procedures imposed by them.
In addition, all equipment and materials shall be in conformity with the most recent international rules, regulations,
standards and recommendation such as, IEC, VDE, BS, JIS, NEMA, DIN, etc.
Standard Voltage
The following values for high and low voltage are standard in Bangladesh.
DISTRIBUTION BUS HIGH
VOLTAGE
LOW VOLTAGE
-
MAXIMUM SYSTEM VOLTAGE
LOCAL, NOMINAL
OPERATING
MAXIMUM PERMISSIBLE VOLTAGE
(by the concerned supply authourity)
: 11 KV
: 12KV
: 415/240V
: 400/230V
: 500V
Frequency
The standard power frequency in Bangladesh is 50Hz.
Design and Construction Requirements
All equipment shall be in accordance with the latest recognised rules of workmanship and modern engineering practice.
All parts of the equipment must be suitable in every respect for continuous operation at maximum output under the
climatic conditions specified above.
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General Specification
Protective Painting
Specifications for Protective painting shall meet the site climatic condition and shall also conform to DIN 55 928:
CORROSION PROTECTION OF STEEL STRUCTURES and the painting work shall have followed paint
manufacturers' instructions.
Earthing of Equipment
Each electrical equipment must be provided with an earthing screw of adequate diameter or an earthing plate.
Insulation coordination
The insulation level for lightning arrestor and transformer shall be as stipulated below, taking into account the maximum
service voltage and the rated voltage according to IEC standard, with appropriate impulse withstand test voltage and
power frequency withstand test voltage values.
The insulation levels for equipment are as follows :Maximum service voltage shall be considered
12KV
According to IEC rated service voltage,
The respective test voltage shall be :
11KV
Impulse withstand test voltage (BIL) shall be :
75KV
Technical Requirements :
The equipment specified in the following items shall withstand the impulse levels and test voltage specified by the
recommendations of IEC as stipulated before. They must be capable of carrying the short time current for three seconds
and must withstand the short circuit (Peak value) current.
The rupturing capacity of the circuit-breakers is indicated in the respective items . The switch gear must be designed
accordingly in order to withstand the mechanical short-circuit stresses.
The Employer reserves the right to have routine tests carried out on each type of equipment at manufacturer's workshop in
presence of the Employer's representative.
Routine test certificates showing the results of all tests performed shall be supplied at a date not later than the delivery
date of the respective equipment.
H.T. Switch Gear.
11KV switch gear must comply with the requirement of IEC-694, VDE 0103, 010, 0111 Part-6 74(draft),0670 Part-7 74
(draft) IEC republication 298.69 recommendation No. 2 and equivalent British Standard (BS 116-1952).
11KV Switch Board shall comprise floor mounted cubicles, free standing type, for indoor installation, pre-fabricated and
factory assembled. The individual cubicles shall be made of strong galvanised sheet steel (minimum 14SWG) at all sides
with steel angles and channels welded together.
The rear of the board shall be covered and the top shall be provided with pressure relief flaps. The bottom shall be open
to allow connection of cables via end boxes, with necessary holding steel members and clamps provided.
The front shall be provided with sheet steel doors with special locking devices and viewing glasses in order to see the
condition of the switches and the contact. On top of the cubicle a cabinet of sheet steel enclosing relay and meter shall be
provided.
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General Specification
The steel members and sheet steel parts after being cleaned by sand blasting shall be painted as per General Notes,
General - Painting for protection against corrosion under high humidity. The single bus bar system shall be of copper
bars to withstand the required amperage. They are to be mounted on cast resin insulators in each cubicle.
The single bars shall be marked by the colours as per VDE or BS standard.
Circuit Breaker:
The circuit breaker shall comply with VDE specifications 0670, Part-1, IEC Recommendations, Publication 56, BS 116
or equivalent ANSI and UTE specifications.
Technical data for circuit breaker.
Nominal system voltage
Rated current
Rated short circuit Breaking current
Maximum rated peak withstand current
Rated Impulse withstand voltage
Power frequency withstand voltage (1 minute)
:
:
:
:
:
:
11KV
630A
20KA
50KA
75KV (Peak)
28KV
11 KV Drop Out Fuse Cutout :

General

Application
11 KV Distribution Transformer

Installation
Outdoor on cross-arm angle/channel structure mounted on
poles.

Nominal rated voltage
11 KV

Maximum design voltage
12.5 KV

System frequency
50 Hz

Continuous current rating
100 Amps

Fuse link continuous rating
In conformity with the capacity of the Transformer.

Maximum ambient Temperature
50oC

Fuse interrupting Current (Minimum)
8.0 KA Symmetrical RMS.

Fuse link type
Medium melting, High surge

Fuse link co-ordination
Shall co-ordinate with existing system protective equipment.

Basic insulation level
95.0 KV

Standards
Performance, Design and testing shall be in accordance with the
latest editions of BS, ANSI, NEMA, IEC, JIS or equivalent
standards unless otherwise specified herein.
Earth Switches
Earth switches shall be generally in accordance with BS-3078 where applicable and shall have short time current ratings
as mentioned in the Schedule of Items.
Switches used within a fully mechanically interlocked system may be assigned a discharge duty only. Where earth
switches are used within a non-interlocked system they shall have short time current ratings either to the maximum line
infeed or to the main bus-bar fault level whichever is applicable.
Contact arrangements on earth switches shall be designed so as to minimise mechanical deflection forces at the top of the
post insulator. Switches shall be manually operated with the three poles mechanically ganged. Mechanical interlocks only
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General Specification
shall be used.
The main bearings, pins etc. shall be of self-lubricating type to minimize routine maintenance over long periods of service
in polluted atmospheric conditions.
Current Transformer:
Current Transformer shall comply with BS 3938, VDE 0414 and IEC 185
The CT shall be cast resin insulated with class 10P10 for protection and class 0.5M5 for metering; burden shall be
10/15VA (min.) for metering. The rated over current factor and burden shall be matching with operating burden of the
connected equipment to prevent the instruments from being damaged.
Potential Transformer:
Potential Transformer shall comply with IEC 86. The PT shall be cast resin insulated with class 0.5 for metering and
protection. Burden shall be 50VA each for metering and for protection (Total 100VA). The PT shall be protected by
HRC fuse. The PT secondary shall be protected by MCB.
Relay:
Relay shall be suitable for sensing the overcurrent, the phase to phase fault and phase to earth fault with IDMT
characteristics. The tripping system shall be capacitor compensated D.C 24/48 volts battery operated or 110V AC from
PT operated shunt-tripping coil, mechanical ON/OFF/TRIP indicator.
Wiring inside the cubicles shall be minimum 1.5 mm2 area and with tinned copper conductors. Current circuits shall be
made with minimum 2.5mm2 area and with tinned copper conductors.
All cubicles, frames, transformers, measuring and relay circuits shall have protective earthing. Each cubicle shall be
provided with earthing bolts and earthing parts. The bus-bars shall be of copper and fully insulated at their supports.
Complete physical dimensions and electrical characteristics of the equipment offered shall be furnished along with the
Bid.
Three Phase Power Transformer
The Transformer shall comply with BS 171, 1978, IEC 76, 1976, VDE 0532 etc.
a)
Oil immersed Indoor type
:
b)
c)
d)
e)
f)
g)
h)
i)
g)
k)
l)
m)
Rated capacity
Rated frequency
Rated primary voltage
Rated secondary voltage
Tap changing
Phase connection
L.V. neutral
High voltage terminal
Low voltage terminal
BIL level
Maximum system voltage
Cooling
:
:
:
:
:
:
:
:
:
:
:
:
With on load tap changer, buchholz relay,
temp. censors etc.
As stated in the Bill of Quantities.
50 Hz
11KV
0.415KV
± 10% (on load) on high volt winding
DYN11
Brought out
Suitable for mix. 185 mm sq. cable connection.
Suitable for BBT connection.
75KV (HT side)
12KV (H.T. side) 0.5KV (L.T. side)
As per schedule
The Bidder must furnish the following data at 75 Degree Celsius
l)
Iron Loss at rated voltage and frequency.
m)
Copper Loss (including supplementary eddy-current loss) at continuous rated current (50 c/s) and for winding at
40 Deg.C ambient temperature with tap changer in middle position.
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General Specification
n)
o)
p)
q)
r)
s)
t)
u)
Impedance voltage with tap changer in middle position.
Voltage drop referred to rated voltage at rated load with tap changer in middle position and at unity pf.
Permissible maximum asymmetric three-phase short circuit current referred to rated current.
Rated no load current (RMS value referred to rated current).
Type of windings with conductor materials
Class of insulation material.
Voltage regulation
Temperature after continuous rated load at 40oC ambient temperature :
In windings
Core
v)
One minute double power frequency inducted test voltage applied to :
H.V. Line Terminal.
L.V. Line Terminal.
L.V. Neutral.
w)
Impulse test voltage 1.2/50 micro second full wave positive and negative polarity applied to:
H.V. Line Terminal.
L.V. Line Terminal.
L.V. Neutral.
x)
Weight of :
Iron Core.
Copper.
Low Tension Switch Gear
The low tension switch gear shall be pre-wired, free standing floor mounted type.
The switch gear shall have the following ratings :
- Operating voltage
:
415 Volts, 3 phase, 50 hertz
- System
:
Direct earth
Switch Gear Design
The switch gear shall be pre-fabricated, complete and ready for erection on the site.
The switch gear shall be totally enclosed. All live parts shall be adequately and efficiently protected against accidental
touching.
The switch gear cubicles shall conform to relevant provisions of BS/IEC/NEMA/VDE/JIS standard and shall be adequate
in all respects to accommodate the cables/BBT, switch gears, meters, cable terminations and interconnections as indicated
in the schedule/specifications/drawings, and be provided with lockable doors. All apparatus and other components shall
be easily accessible from the front as required for inspection, replacement and repair. The switch gear shall be of tropical
design
The switch gear panel shall be designed for asymmetrical short circuit current of 100KA during 1 second for protection
against internal arcing faults. All parts of the switch gear including apparatus shall be designed to withstand, without
being damaged, the mechanical and thermal strain of this current or where protected by circuit breakers the interrupting
current of the circuit breakers.
Outgoing cables shall be arranged in separate spacious cable spaces.
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General Specification
Interior control wiring shall be accommodated in plastic conduits. Wiring inside the cubicles shall be made with minimum
1.5 mm2 area and with tinned conductors. The switch gear shall be designed keeping provision for additional space of
approximately 20% for future extension.
Apparatus
The switch gear shall be arranged in accordance with the relevant layout drawings. The switch gear shall be of modular
type design. The apparatus of each functional group shall be assembled on a common base.
Cubicle Construction
The metal thickness shall be (minimum 14 SWG and galvanised) at all sides with steel angle and channels welded
together.
The paint shall be as per General Notes, General - Painting, grey or approved colour. The paint thickness shall be
adequate and chemical resistant to paraffin, petrol, dilute acids/allkalis (10%).
Creepage and clearance paths shall conform to VDE 0110 insulation group C or UL508 table 18.1 and BS162 table 4.
The cubicle shall be dust and vermin proof.
Bus-Bars (Main and Secondary)
There shall be five nos of bus-bars i.e. L1, L2, L3, N & PE. The three phase conductors of single bus-bar systems shall be
positioned immediately below the top plates of the sections. The PE earth continuity bar shall be mechanically bonded to
the distribution sections and the neutral bar shall be carried on insulated supports. Bus bar in the end section shall have
the facility for subsequent extension.
The busbars shall be of copper and designed, manufactured and tested to comply with BS 159 or equivalent or
American/Continental standard and to provide a fault level of 100 KA (rms) for 0.1 second. Secondary bus-bar risers
shall be insulated. Bus-bar short circuit current rating shall be minimum 80 KA (rms) at cos Θ = 0.2 for 1 sec.
Bus-Bars and Connection Supports
Busbars and connections shall be supported by synthetic resin bonded paper to BS 1137 or equivalent or American or
Continental standard.
Cable/BBT Entries and Terminations
These are meant for PVC insulated cables/BBT, and shall be arranged for access as stated. All cable sockets for incoming
and outgoing cables shall be provided.
Earthing Link and Earthing Bars
Separate earthing bars shall be provided. A suitable earthing link shall be provided for earthing the neutral bars.
Instrumentation
Panels shall have meters (of suitable scale, class and accuracy) as specified in the schedule of items.
Labels
Labels for circuit identification shall be provided.
Indicating Lamps
Panels shall have indicating lamps as specified. The colour for the main steel work shall be light grey. The busbars and
copper connections shall be painted copper electro-tinned and cover fixing screws and other fixing shall be finished bright
shine.
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General Specification
MCCB/MCB
The MCCB/MCB's shall be quick-make, quick-break type, and shall have inverse-time limit characteristics with
instantaneous magnetic trip elements functioning on overloads above the normal operating range. All circuit breakers
shall be "trip-free". Ratings of breakers shall be in accordance with Schedule of Items. All lugs must be of the solderless
mechanical type. The Miniature Circuit Breaker must comply with B.S. 3871 : Part-I (1965) category M4 (5A-60A).
Rated voltage 240/415 A.C. 50 Hz, interrupting capacity 10 KA capable of providing overload and short circuit
protection, through thermal and magnetic trip actions respectively; temperature rating 400C, tropicalized (moisture-fungus
corrosion treated), with contacts of silver alloy, terminal capability upto 25mm2 wire. The Moulded Case Circuit Breakers
must comply with BS 3871: part-2 (1966). Rated voltage 600V A.C., 50Hz with overload and short circuit protection
with thermal and magnetic tripping action; interrupting capacity of 25-50 KA indicated in the Schedule of Items
temperature rating 400C tropicalized (moisture-fungus corrosion treated), with appropriate terminal capability.
Characteristic curves shall be submitted along with the offer.
Automatic, Reactive Power Control
Equipment with Capacitor Bank
The Power Factor Improvement Plant shall be galvanised sheet steel clad, dust and vermin proof, free standing, floor
mounting, indoor type. The centrally controlled automatic PFI Plant shall be of compact design and be suitable for the
reactive power. The PFI Plant shall be as per schedule, 415 volts, 50 Hz, SF6 or dry NON "PCB" self healing type
capacitor banks discharge resisters, with associated control unit. The control unit shall be internal part of the PFI Plant
and shall comprise CT of adequate rating. There shall be automatic Power factor correction relay to keep the automatic
power factor almost constant and independent of load fluctuation. PF Meter, indicating lamp ON/OFF switches, switching
step indicator etc. shall be included. The automatic control must be non-responsive in a certain range to eliminate hunting.
H.T. Cable
(a)
Cable
Work under this item comprises supply and installation of High Tension cables with copper conductors, PVC
insulated, field limiting conducting layers over each conductor and each core insulation, concentric shields of
copper over individual cores, flat wire armouring over the common covering of cores, helical steel taping and
PVC sheath.
It shall be made and tested according to latest VDE 0271/3.69, VDE 0472/6.65 and VDE 0472a/3.69.
It shall be good for laying indoors, outdoors, underground and in water.
Rated voltage, E/E=10.0/5.8KV, Continuous permissible service voltage = 12.0/7.0KV.
(b)
Filled-in Trenches for laying cables
The size of cable trench shall be minimum 915mm (36") in depth and 457.20mm (18") in width for each cable
to be laid. Where more than one cable is to be laid, the width is to be increased by 152mm (6") for each extra
cable. Trench digging shall not commence until all cables are procured and brought to site store.
Excavation of trench bed may require shuttering and shoring of trench sides, bailing out water, and the trench
bed shall be dressed, cleaned and levelled. This shall be followed by 152mm thick cushioning by sand of min.
F.M. 1.0 in the bed over which the cables will be laid. After laying of cables first class bricks shall be placed as
separators between the cables. Thereafter sand filling shall be done with sand of F.M. 1.0 upto 152mm over the
top of the largest cable in the trench after which one layer of flat brick is to be placed along the length and
breadth of the trench as a mechanical protection against injury and as a signal that a power cable is laid under
the bricks.
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No covering of cable trenches shall however be done before inspection and approval by the Engineer. If the
Engineer notices any damage to the cable or any other fault which requires remedy or replacement of the cable
the Contractor shall do the needful promptly at his own cost.
The rest of the trench shall be filled with earth, watered and rammed in 152mm layers. After installation of the
cables, original ground conditions are to be restored, be it brick pavement, drains, concrete road or any other
construction. All costs involved in mending good of the damages shall be fully borne by the Contractor.
The Cables are to be placed in trenches with slight curve so that it can give way when the earth settles later on.
Cables shall be laid into or out of the ground through G.I./PVC/RCC Pipe of appropriate size decided by the
Engineer. The length of the pipe over the ground shall be 1.2m (4 ft.).
The cable route should be as direct as possible and must receive Engineer's approval before excavation. The
routing for H.T. cable shown in the plan is not firm on account of uncertainty of Hook-up point with City
Supply.
The routing plan will need firming up after consultation with City Supply Authority.
Cast iron cable markers shall be used at every turning point of the route and at 15m (50 ft.) intervals in straight
routes of the trenches.
All cable runs shall be kept at least 610mm (24") clear of gas, sewer, water and other services pipes in horizontal
plane. Where necessary the cable run shall be re-routed to maintain the specified gap.
Trenches for H.T. Cables shall be maintained at a minimum 610mm clear distance from an adjacent L.T. cable
trench.
All cable bends shall have a radius of not less than 24 times the overall diameter of the cable for armoured
cables, and 20 times the diameter for non-armoured cables. But the radius shall not be less than twice the
diameter of the cable drum in any case.
Great care shall be exercised to avoid damage during handling of the cables and to prevent formation of
"Kinks". The cable drums shall preferably be conveyed on wheeled cable-drum carriers and unrolled and laid
directly from the drum carrier along the trench over rollers of approved construction. Carriage by trailers or
trucks can be allowed if proper care is taken during unloading the drums and unrolling is done after placing the
drum on jacks and spindles. Dragging the cables over the surface of earth along the trench shall not be allowed.
The cables should be carried and unrolled in the direction indicated on the drums by the manufacturers.
The cables shall be terminated at required locations and as directed by the Engineer.
152mm dia G.I. pipe (or other size approved by the Engineer for L.T. cables) shall be provided for all road and
drain crossings. These pipes shall be laid direct in the ground without any sand bed, sand layer, brick, or cable
covers.
When trenches are left open overnight and where road is to be cut, the Contractor shall exhibit suitable danger
signals such as banners, red flags and red lamps at his own cost. Temporary arrangement by placing wooden
sleepers/sheet steel etc. across the road cutting for vehicular traffic are also to be made by the Contractor at his
own cost. The Contractor shall be wholly responsible for any accident which may occur due to his negligence.
G.I. pipes of appropriate size and length shall be used to protect the cable from all sorts of mechanical injury,
every time it climbs up/down the pole/steel structure. Cable terminals of appropriate type, size and capacity shall
be used every time outdoor termination of cable is followed/preceded by bare overhead lines/Busbars/Terminals etc.
All surplus earth shall be removed to the indicated places by the Contractor at his own cost.
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General Specification
Any damage done by the Contractor to any other agencies during or as a result of cable laying operations shall
be made good by the Contractor.
(c)
Insulation Test
Insulation test of the whole installation shall be carried out using 2000V Megger in presence of authorised
representative of the Engineer and result to be submitted to the Engineer for approval.
H.Pole Assembly
The work under this item comprises supply and erection of painted G.I. H-Poles including all accessories at locations
shown on the drawings. The work also includes excavation and foundation work.
The pole shall be fabricated by welding two different sizes of G.I.pipes.The dimension of the pole is as follows:
Height
Base dia
Top dia
35 ft.
(10.69M)
6 inches (152.4mm)
4 inches (101.6mm)
Length of Different Sections
Base portion
Top portion
25 ft.
10 ft.
(7.62 M)
(3.07 M)
The welding shall be continuous and smooth. The strength of the joint made by welding shall not be less than that of the
G.I. pipe. The H-pole shall have mild steel top cap, and mild steel base plate of size 600 x 600 x 4.76mm, properly
welded at the base. The H-pole shall have one 9.53mm dia G.I. nut, bolt and washer just above the ground for fixing pole
earthing. The poles shall comply with relevant section of ASTM specifications. After fabrication, the poles shall be
painted as per General Notes, General, -Painting.
All non treated ferrous accessories shall be hot dipped galvanised. Concrete in foundation shall conform to RC used in
Building of 3000 psi grade but using jhama brick chips as coarse aggregates.
Water in the hole, if any, shall be bailed out. Only smooth surface wooden shuttering of adequate strength and size shall
be used. The surface of concrete after pouring shall be so finished as not to necessitate plastering. Curing shall commence
within 12 hours of casting and shall be continued for 28 days. Compression tests of concrete shall be performed on 6 x 12
cylinder samples collected during casting.
The casting shall be of the size 457 x 457 x 2210mm (height) of which 1.83m (6 ft) shall remain within the ground and
380mm (15") above ground.
INDOOR TYPE HIGH TENSION SWITCH GEAR/LOW TENSION SWITCH GEAR/POWER FACTOR
IMPROVEMENT PLANT.
(a)
Description
The work under this item comprises of supply and installation of indoor type H.T. Switch Gear/ LT Switch
Gear/P.F.I. plant for the project.
(b)
Materials
The indoor type H.T. Switch Gear/LT Switch Gear/P.F.I. plant shall be 14 SWG galvanised sheet steel
fabricated, fully waterproof and suitable for free stand. The H.T. and LT Panel shall have solid neutral link and
live copper bus bars mounted on best quality porcelain insulators suitable for 11 KV/0.415 KV, 3 phase, 50Hz
operation. Knockouts shall be provided for cable/BBT entries and exits. The circuit breakers shall be so
arranged as to keep the knobs only projected over the inside cover. A hinged cover on the front with additional
gasket shall be provided with locking arrangement. All these cubicles shall be provided with a number of
earthing points with a copper block of size 152 x 25.4 x 6.35mm. Foundation nuts and bolts, hot-dip galvanised
after fabrication, shall be supplied with the board.
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General Specification
The three gears are separate and shall be laid out according to drawings.
(c)
Installation
The three gears shall be installed in location shown in the plan. It shall be understood that this location is only a
guide and the actual location shall require final approval by the Engineer prior to installation.
LOW TENSION CABLE
Materials
1.1
Single core cable and conductors
Single core low voltage cables and conductors shall be as per B.S. 600, B.S. 6346, or equivalent VDE
specifications of copper conductor and PVC insulated. Conductors shall have 600/1000 volt grade of PVC
insulation. All sizes over 2.5mm2 shall be stranded.
1.2
Multicore Cables
(a)
Multi-core low voltage cables shall be PVC insulated PVC sheathed non-armoured, direct burial
type, termite proof, made and tested according to VDE 0472/6.65 and VDE 0472/3.69, rated voltage
being 600/1000V.
(b)
Filled-in Trenches for laying cable
L.T. Cable Trench shall maintain a clear 610mm distance from an adjacent H.T. cable trench. The
size of the trench shall be 840mm in depth and 460mm in width. Where more than one cable is to be
laid in the trench, the width of the trench shall be increased by 76mm for each extra cable for size
below 70mm2 and 152mm for bigger size cables.
All the specifications for installation of H.T. cables in Cable Trenches laid down in para 4 (b) shall
be applied here.
All chasing and passage necessary for laying of cable indoor shall be done by the Contractor at his
own cost and the body of the building in which the chases/passages are done shall be made good by
the Contractor at his own cost to the satisfaction of the Engineer.
(c)
Insulation test
Insulation test of the whole installation shall be carried out using 500V Megger in presence of
authorised representative of the Engineer and result submitted to the Engineer for approval.
EARTHING
(a)
Description
The work under this item comprises supply and installation of GI pipe electrode, brass clamp and earthing lead.
G.I. pipes shall conform to the requirements of ASTM A120-83. The bore of the pipes shall be free from any
burs. The G.I. pipe shall be so bent using pipe bending equipment that the pipe bore is not deformed or reduced.
Earthing lead shall be tinned electrolytic annealed copper wire with 100% conductivity at 200C (680F).
(International Annealed Copper Standard) with weight resistively of 0.15328 ohm-gram/m2 at 200C(680F) and
density of 8.894 gm/cc. All fastening nuts, bolts and clamps made of steel hot-dip galvanized after fabrication
shall also be supplied by the Contractor.
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General Specification
Transformer Neutral/S.S.Equipment/Feeder Pillar Earthing
37.33m (120 ft) long and 38mm dia G.I. pipe earthing electrode shall be installed by tube-well sinking method.
The G.I. pipe shall have holes each 6.35mm dia at every 305mm internal of the entire length of the pipe. The
terminal connected to the earthing electrode shall be a copper clamp and shall be covered with bitumen
impregnated jute cloth in three layers and melted bitumen shall be liberally applied as a first coat and in between
each of the three layers of bitumenised jute cloth. The final wrapping shall be surrounded by thick coat (10mm)
of melted bitumen.
2 SWG earthing lead conductors shall be continuous and no joints shall be allowed in a run between earthing
electrodes and earthing/neutral point in the Transformer/S.S. equipment. The routes shall be as direct as
possible. No sharp bends shall be allowed. Connections to the two ends of a conductor run shall be electrically
continuous and mechanically strong. When the conductor runs horizontally on the ground, it shall be buried
0.91m underground by cutting trench of adequate width. The trench shall be backfilled with earth after
installation of the earthing lead.
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General Specification
SPECIFICATIONS FOR AUTO-MAINS FAILURE DIESEL ENGINE GENERATOR
1.
Item
DIESEL ENGINE Driven A.C. Generating set having a prime power output as mentioned in the Bill of
Quantities (Prime power) standard voltage 400/230 volts, 3 phase, 50 Hz, 4 wire at 1500rpm under condition of
normal temperatures and pressures.
2.
General Description
The engine and alternator assembly (with sound attenuated acoustically treated canopy) shall be directly flange
coupled, the alternator being driven by a flexible coupling connecting engine fly wheel to alternator rotor.
The unit shall be mounted together with cooling radiator on a fabricated, heavy steel frame of all welded
construction designed to accurately align and support the assembly. The base frame is to be predrilled to allow
for built-in anti-vibration mounts and is to be provided with special lifting arrangement for case of handling and
safety purposes.
There shall be arrangement for manual/automatic battery electric start being operated from the main control
panel which shall also include all monitoring and protection devices covering the mechanical and electrical
systems.
3.
Detailed Specifications
Auto-Mains failure diesel engine generating set having a continuous rated output as mentioned in the Bill of
Quantities to BSS 5514, DIN 6271 ABGSMA at 0.8 Power Factor at 415/240 Volts, 3 phase, 4 wire, 50Hz at
1500rpm under conditions of normal temperatures and pressures with 10% over load for one hour at conditions
specified under B.S. 649, 1958.
4.
Base Frame
The engine and alternator shall be mounted on a fabricated steel type base frame of welded construction
adequately designed to resist bending and torsional forces. The base frame shall accurately align and support the
assembly and shall provide lifting points and location points for securing to the foundation.
5.
Coupling
The alternator casing shall be flange mounted to the engine flywheel housing and the rotor shaft, coupled to the
engine flywheel through a flexible element to minimize torsional vibration throughout the operating range.
6.
Engine
The engine shall be of multi cylinders, 4 stroke, naturally aspirated/turbocharged, pressure lubricated, direct
injection, water cooled, industrial diesel engine of developing the rated BHP at 1500RPM at NTP conditions.
The engine shall be complete with close control governing to BSS 5514, 1979, DIN 6217 ISO 3046 Class- A1
Fuel Injection equipment with a)
b)
c)
d)
e)
f)
g)
h)
i)
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Fuel oil filters and pressure gauge.
Tachometer
Lubricating oil filters and pressure gauge.
Air cleaners/filters.
Indicating Lamps ON-OFF-TRIP
Fuel solenoid energized to run.
Lubricating oil pressure pump and temperature gauge.
Water circulating pump.
Battery charging generator and regulator.
185
General Specification
j)
k)
l)
m)
n)
o)
p)
7.
1-set of protection equipment to give alarm and shut down on low oil pressure, high water temp. (for
water cooled engine only)
Precision governor.
Starter motor.
Fuel solenoid.
Thermostatically controlled cooling system and by pass system.
Service power meter.
Flywheel, fan and pulley guard protection.
Radiator
Heat rejected to the engine jacket water shall be discharged to the atmosphere through a close coupled radiator.
The radiator shall be sized to cool the engine continuously while operating at full rated load and at site
conditions. It shall be a folded core design consisting of individually replaceable core assemblies sealed between
the top and bottom tank and which can be replaced individually at the job site.
8.
Governor
The engine governor (Class-A1 governor complying with BS 5514, Part 41979 DIN 6217 & ISO 3046/IV 1978)
shall be Electronic Speed Control with Electro-Hydraulic or Electric or Electric Actuator Speed drop shall be
externally adjustable from Zero to 8% from no load to full rated load. Steady state frequency regulation shall be
+/-0.25%. Speed shall be sensed by a magnetic pickup off the engine flywheel ring gear. A provision for remote
speed adjustment shall be included. The governor shall incorporate provisions for limiting fuel during start-up,
include capability for actuator compensation adjustment for increased stability and protection from voltages
spikes and reverse polarity.
9.
Engine Cooling
The diesel engine shall be cooled via a tropical air blast heavy duty radiator with engine driven pusher type fan,
complete with water, circulating pump, radiator guard, thermostat and by pass system. The engine jacket cooling
system shall be a closed circuit design with provision for filling, expansion, and deaeration. The cooling pump
shall be driven by the engine Auxiliary coolant pumps required for heat exchanges or separate circuit after
cooling shall also be engine driven. The cooling system shall tolerate at least 172.4 kpa(25 Psi) static head.
Cooling temperature shall be internally regulated to disconnect external cooling systems until operating
temperature is achieved.
10.
Lubricating System
Wet slump force feed lubrication system by gear driven oil pump incorporating replaceable oil filters.
11.
Exhaust System
The engine shall be supplied with Acoustic type silencers, flexible bellows sections and rigid exhaust pipe of suitable length, suitable for use with
Vee form engine, supplied loose for site erection. The complete exhaust system shall be designed to prevent any
de-rate of the engine due to excessive back pressure. All exhaust components are to be finished with heat
resistant paint. The silencer shall be residential/hospital type with a very low noise level.
12.
Anti-vibration Mountings
A set of anti-vibration mounts shall be supplied loose for positioning beneath bed frame when the skid is
delivered to site. These have their own in-built levelling device and friction pad, therefore fixing to the floor is
not necessary.
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General Specification
13.
Fuel System
The unit shall be supplied with a base mounted fuel tank in corporated in the base frame of the unit providing
sufficient fuel for 8 hours continuous full load operation. The base shall be pressure tested prior to assembly and
will incorporate dial type content gauge, filler cap, vent pipe, drain cock and all necessary fuel connections. All
pipe terminations shall be completed during works assembly. The system shall include arrangement for low level
and high level alarm system of fuel.
The fuel system shall be integral with the engine. It shall consist of fuel filter, transfer pump, injection pumps,
lines and nozzles. The transfer pump shall deliver fuel under low pressure to individual injection pumps - one for
each cylinder.
The injection pumps shall be driven from the camshaft and simultaneously controlled by a rack and pinion
assembly that is actuated by signals from the engine governor. The pumps shall be of a variable displacement
type to alter the volume of fuel delivered to the spray nozzles according to load demand.
The nozzles shall inject fuel directly into the cylinder in the optimum spray pattern for efficient combustion. A
set of rotary type hand operated pump shall be supplied with 3 metre of flexible pipe, suitable for manual fuel
transfer in the daily service fuel tank.
14.
Fuel Line
Flexible fuel lines between engine and fuel supply shall be installed to isolate vibration.
15.
Engine Starting
The engine shall be fitted with manual/automatic electric starting and transfer of load / auto synchronizing by
means of a starter motor arranged to engage with the flywheel. The engine starting system shall include 12/24
volt DC starting motor(s), starter relay, automatic reset circuit breaker to protect against but engagement, heavy
duty dry-charged lead acid batteries, battery rack and necessary cables. Batteries shall be industrial type,
maintenance free, lead acid type mounted near the starting motor. A mains operated battery charger shall be
mounted in the control cubicle. A corrosion resistant or coated steel battery rack shall be provided for mounting.
Required cables will be furnished and sized to satisfy circuit requirements. The system shall be capable of
starting a properly equipped engine within 5 seconds at ambient temperature.
16.
Batteries
Batteries for starting and control shall be selected and supplied by the generator manufacturer. They shall be
heavy duty lead acid type with through partition connectors, and housed in a hard rubber or polypropylene case
with provision for venting.
Starting batteries shall be rated 12/24 Volt DC with a minimum ampere-hour CCA as per manufacturer's
recommendation. Sizing shall consider specific application requirements of engine oil viscosity, ambient starting
temperature, control voltage, overcharging and vibration.
17.
Alternator
Brushless Salient pole rotating field, self-exciting, self-regulating, drip proof screen protected type
single/double bearing construction with integral electronically operated automatic voltage regulator providing
voltage control to within +/- 1% of nominal range, no load to full load and at all power factors between unity
and 0.8 lagging and with a maximum 5% prime mover speed variation. Voltage regulation and wave form shall
conform to BS 4999 Part 40/VDE 0530.
Class H insulation on both rotor and starter windings and with enclosures to IP 21 of BS 4999 Part 20, IEC and
DIN standards. The alternator shall the requirement of BS 5000 and radio suppression to BS 800 and VDE class
G and N.
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General Specification
18.
Control and Switch Gear Panel
The control system switch gear shall be comprised of cubicle for each diesel engine generator set plus auxiliary
cubicles or cubicles as required for CENTRAL COMMAND the change over contactors/circuit breakers and
shall be factory assembled to form a station switchboard lineup. The switch board lineup shall be free standing,
self-supporting, 14 SWG galvanised sheet steel clad, dust and vermin proof metal enclosed for indoor service
with internal steel barriers forming control, breaker, bus compartments plus removable screw secured rear sheets
for access to the bus compartments and hinged front doors for access to control and breaker compartments.
Open bottom areal areas shall be provided in cubicle for field cable/exit.
The switch gear shall be completely enclosed, dead front, suitable for self-supported floor standing type
completely factory assembled. Safety to operating and maintenance personnel shall be of first importance in the
design, equipment selection, and manufacture of the equipment. Arrangement of sub-assemblies within the panel
shall permit maximum accessibility to all parts, bus, and incoming and outgoing cables by Govt. recognized
switch gear industry manufactured and tested in accordance with IEC/VDE/JIS/NEMA/BSS Standard.
Sheet metal members shall be bolted and/or welded together to achieve adequate strength and rigidity to
withstand short circuit fault currents of 50,000 amperes symmetrical. Natural ventilation shall maintain a
minimum enclosure temperature of 60 deg.C over 40 deg.C ambient temperature when maximum equipment is
installed including cable and bus. Bolt holes shall be provided in the floor standing panel for hold down and
leveling requirements, while all enclosures will provide lifting eyes which can be removed from blind tapper
holes. Louvers shall be provided at top and bottom of floor standing enclosures, and shall be rain-proof and
screened to minimize moisture and rodent/insect intrusion.
The control/switch gear panel shall be constructed from 14 SWG galvanised sheet steel shall be painted as per
General Notes, General, -Painting, with full width hinged door for internal access to components, timer
adjustments and the inter-connections board. All fascia instrumentation and controls shall be recessed for safety
and protection.
Doors shall not sag when all options are installed. Front covers on all instrument compartments shall be hinged
and secured with latch-type hardware. Breaker compartments extending the width of the enclosure shall hinge on
one side and be screw secured on the opposite side. The circuit breaker compartment and cable area shall be
isolated by either fixed or removable metal barriers from the instrument compartments. Physical contact with the
circuit breaker shall not be possible when only the instrument door is open. Adequate space for top or bottom
cable entrance and/or exit shall be provided within the enclosure. Conductor sizing shall be based on NEC,
Table 310-16 75 deg.C conductor insulator rating.
The controls protection and monitoring systems of the generator set and its operation shall be responsibility of
the generator set manufacturer. All sub-system components, interfaces and logic shall be compatible with engine
mounted devices.
The control panel shall be complete with all internal wiring cables and accessories necessary for satisfactory
operation and maintenance. The control system shall be manually reset once the fault is rectified. All the failure
circuits must incorporate a "press to test" facility which when operated will simulate the fault and shut the
generating plant down.
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General Specification
1.
WINDOW TYPE AIR CONDITIONER
1.1
Supply of Items
Window Type Air-Conditioner as per schedule complete with Fresh Air and Room Air Inlet, Compressor, Fan
with Motor for Air supply, Room Air Exhaust and all accessories complete. Capacity of the unit shall be as per
schedule of materials.
The units shall be factory built, tested and ARI rated. The performance shall be in conformity called for in the
Schedule of Items with catalogue performance table which must be submitted along with the offer.
The Contractor may quote for the nearest standard model of capacity higher than that as but the dimension
should meet the requirement of the existing operation room and should be fitted as per drawing.
The Window Cooler shall be constructed of heavy gauge galvanized sheet steel factory-assembled with stiff
supporting. The channels shall be successfully assembled with removable rivets for rigidity and with zinc plated
self-threaded screws to permit complete accessibility for inspection and servicing.
The Window type Air-Conditioning unit shall have horizontal discharge and return shall also be horizontal as
shown in the drawing.
The unit shall be equip with a drain pan to collect the condensate from cooling coils. The drain pan shall be
constructed with heavy gauged sheet steel and shall be extended under the complete coil and fan section.
The unit shall be complete with fan, low velocity washable filter section, fan motor with starter etc. and all
control accessories with sensor, actuator, motor linkage, low voltage transformer etc.
Control Panels should have temperature and fan speed controller with required remote thermostat, actuator all
complete to control the temperature & Humidity at desired level.
Refrigeration circuit shall be complete with copper pipe fittings, suction pipe insulation, control valve, filter
drier, moisture indicator, service valves etc. complete.
Window Cooler unit casing shall be made fully weather-proof Wall Type installation in a area having annual
rain fail over 70", temperature upto 105oF and 90% RH. The unit shall be suitable to operate at 400 V/ 50 Hz / 3
phase power supply.
1.2
Installation of Items
The unit shall be installed at the location as shown in the drawing and as per direction and recommendation of
the manufacturer. Before installation the contractor shall have to check the equipment and accessories and in
case of any materials missing or damaged he shall immediately report the matter to the Consultant. Uncrating
checking, cleaning and installation of the unit shall be done by the Contractor. Required wall breaking and
repairing shall be done up to the satisfaction of the Engineer-in-charge.
Window Unit shall be placed inside the wall with the front flash with the inside wall and surface of the back side
should be placed on Angle Iron frame with the machine casing surrounded by 3/8" dia MS rod frame as per
direction and Drawing, approved type rubber isolator shall be used for installation.
All the equipment shall be properly aligned and statically and dynamically balanced.
All the electrical connection, wiring etc. shall be done by the Contractor as per recommendation. Drain water
should properly plumbed. Unit drain piping shall be done with PVC piping as per schedule.
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General Specification
SPECIFICATION OF WORKS
A. CIVIL WORKS
1.
EARTHWORK IN EXCAVATION IN FOUNDATION TRENCH INCLUDING REFILL
The item shall include earthwork in all kinds of soil including slushy soil; stabilising the sides of excavation by
shuttering, shoring, waling, bracing etc. and all dewatering works necessary to keep the excavation dry, the
stabilising and dewatering work being continued till the concrete and/or masonry work within the excavation is
completed.
The item shall also include removal of Temporary Works from out of the excavation and refilling the excavation
(Payable under separate item) after the concrete and/or masonry work within the excavation is completed, the
materials for refilling being such portion of spoils of excavation as are suitable and approved by the Architect
supplemented if necessary, by local sand of minimum F.M. 0.70 or by imported earth. If local sand or imported
earth is used for refill it will be payable under a separate item.
The item shall also include the work of conveyance of surplus spoils of excavation upto a distance of 153M.
measured from the outline of the building and depositing them in uniform layers in the low-lying areas
surrounding the building.
Earthwork in excavation shall not be commenced before the pillars marking the centre lines and Bench Marks
bearing known levels are checked by the Consultant.
Extreme care shall be taken that the bottom level of the excavation never lower than that required by the
Drawings. 5mm depth shall be saved during the mass work; this 50mm material shall be removed and final beds
shall be exposed not more than 12 hours before being topped by masonry/concrete work.
If the Contractor over-excavates in depth beyond the required level, the excess depth shall be refilled by 1:5:7
concrete at Contractor's own cost.
All loose materials and residue of foreign materials shall be removed before masonry work or concrete casting is
commenced.
In any precious material or any object of archaeological interest is discovered during the excavation, attention of
the Employer shall be drawn to it.
In case any utility line is found to lie in or traverse the soil included in the excavation, the lines shall be protected
from injuries or damages due to strikes from excavation tools or due to loss of continuous support. Attention of
the Employer shall be drawn to the presence of utility lines and measures shall be taken by the Contractor,
without additional cost to the Employer, to support them till all works below ground are completed.
2.
PILE WORK
2.1
Description
This work shall consist of construction of reinforced concrete cast-in-situ bored vertical or inclined
piles for abtitments/pier(s) of structures at different locations in accordance with the details shows on
the drawings and to the requirements of these specifications. The contractor shall undertake at the
actual location of such piles foundations, sub-soil investigations in accordance with these specifications
prior to start of the work of pile foundation.
The prevailing soil conditions indicate that no permanent steel easing is required. However, if the
method of pilling chosen by the Contractor requires permanent steel casing, this shall be executed as
described below at Contractor's own cost. No additional payment shall be made for this.
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General Specification
The pile boring shall be, carried out using a temporary steel casing bored to the pile toe or to a level
approved by the Engineer. The temporary easing shall be withdrawn.
Under certain circumstances the Contractor may be permitted to bore all or part of tile pile without
easing under water or using drilling fluid to stabilise the borehole as referred to in this section below.
The piles shall be concreted and reinforced to resist pile loads and Horizontal forces on the pile caps
according to the Drawings and these Specifications.
2.2.
Materials
2.2.1
Steel Casing
This part of the Specification deals with the permanent steel casing. For steel easing used
during the boring of the pile see section below.
The steel of the easing shall conform to AASHTO Standard Specifications M 183-79 (ASTM
A36) or equivalent.
The minimum wall thickness of the permanent steel easing shall be 10mm. The minimum
length shall be from 10 cm above the bottom of the pile cap to 5 metre under the river bed or
into firm strata. If the permanent easing is used in the boring operation or if the handling and
transport require a greater thickness to avoid deformation or buckling, the increased wall
thickness shall he provided by the Contractor at his own expense.
The steel easing shall be furnished in appropriate lengths and the joints shall be approved by
the Engineer.
The easing shall be handled and stored in a in a manner that shall prevent buckling and other
deformation as well as accumulation of dirt, oil and paint. When placed in the work it shall be
free front dirt, oil, grease, paint, mill scale and loose or thick rust.
The outside surface of the permanent easing of piles of piers shall receive two coats of anticorrosion bitumen type paint for a maximum depth of 125mm from the underside of the pile
cap. The paint shall be approved by the Engineer and its application shall follow the
manufacturer's instructions.
2.2.2
Concrete
The concrete shall conform to Section of these Specifications. Cement type 1 shall be used
and the characteristic cylinder strength shall not be less than 25 N/mm2. Concrete placed
under water or drilling mud by tremie shall have a cement of not less than 350 kg/ m3.
The density and consistency of the concrete shall be conform to the tremie casting method and
the maintenance of sufficient workability (slump) of the concrete during the casting, including
reasonably calculated delays, shall be secured by a approved design mix. (including the
necessary retarders and plasticisers), which is tested by trial mixes prior to the pile
construction.
All relevant concrete properties such as slump, time of setting, temperature and strength shall
be measured and defined during the trail mixes.
2.2.3
Reinforcement
The reinforcement shall be complied with if bentonite mud is sued to stabilize the boreholes:
(a)
Supply
A certificate shall be obtained by the Contractor from the manufacturer of the
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General Specification
bentonite powder, showing the properties of the consignment delivered to the site.
This certificate shall be made available to the Engineer at least 4 weeks prior to its'
use. The properties to be given by the manufacturer are the apparent viscosity range
(in centipoise) and the gel strength range for solids in water.
Any other material for the drilling fluid shall be approved by the Engineer.
(b)
Mixing
Bentonite and any other materials shall be mixed thoroughly with clean water to
make a suspension which shall maintain the stability of the pile excavation for the
period necessary to place concrete and complete the construction thereof.
Where saline or chemically contaminated ground water occurs, special precautions
shall be taken to modify the bentonite in fresh water so as to render it suitable in all
respects for the construction of piles.
(c)
Tests
The frequency of testing the drilling fluid and the method and procedure of sampling
shall be determined by the Engineer prior to the commencement of the work. The
frequency may subsequently vary depending on the consistency of the results
obtained. the control tests shall cover the determination of density, viscosity, gel
strength and pH values.
The Contractor shall supply all equipment and experienced operators required to
carry out tests on the drilling mud. No additional payment shall be made for these
tests which shall be considered as an essential part of the drilling operations.
2.2.4
Length of piles
The basic length of pile and its diameter is shown on drawings. The final length shall be
decided by the Engineer on the basis of the results of initial load test on piles and on the basis
of actually boring data observed oil site. Test piles shall be installed as directed by the
Engineer at selected locations at each bridge site.
2.2.5
Method
2.2.6.
General
Pile type and construction methods shall ascertain that the pile shaft shall not be weakened by
contamination of the concrete by sectional reduction, by washing out of cement, by breaking,
pulling of temporary casings or in any other way, including the construction of neighboring
piles.
a)
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Assumed Procedure
The following construction procedure has been assumed in the tender design. Final
construction procedure shall be as approved by the Engineer prior to the start of the
piling operations.
i)
Place permanent steel casing, if required, in position and embed casing toe
into river bed or firm strata. If no permanent steel casing is specified a
sufficient length of temporary steel casing shall be used to stabilise the
upper part of the borehole.
ii)
Bore and excavate inside the steel casing down to casing to level, or an
approved level, continue excavation to final pile tip level using either
temporary casing under - water or approved drilling mud. Water level
inside casings shall at all times be at least 50mm higher than outside the
casings.
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General Specification
b)
iii)
All mud and/or sedimentation shall be carefully cleaned from the bottom of
borehole.
iv)
Place reinforcement cage, inspection pipes etc.
v)
Place under water concrete or drilling fluid continuously by use of the
tremie method.
vi)
Withdraw the temporary boring casing concurrently with concreting to the
instructed level.
vii)
After hardening, the top section of the concrete pile shall be removed to
reach sound concrete.
Approval of Construction Method
In the tender, the Contractor shall describe the construction method he proposes,
including information on boring equipment, materials, methods of work, control of
quality and bearing capacity and, if any, the name of the Sub-contractor. The
Contractor shall submit references from similar jobs carried out by him or by his
Sub-contractor.
During contract negotiations tile Contractor shall submit all requested supplementary
detailed information in writing.
After the Contract has been awarded to the Contractor, he shall prepare a detailed
programme and a establish a procedure for the pile construction in accordance with
the above information for the Engineer approval.
The detailed programme shall contain all information on materials, equipment,
methods of work etc.
The Engineer's approval shall not relieve the Contractor of his responsibility for the
pile construction.
No boring equipment or materials shall be imported before the Contractor has
received the Engineer's approval in writing.
2.2.7
Setting Out Piles
The Contractor shall verify the easing position for each pile during and immediately after
placing tile casing and submit the final location for the approval of the Engineer.
2.2.8
Diameter of Piles
The diameter of a pile shall be not less than the specified diameter.
2.2.9
Tolerances
The centre of the completed pile at the cut off level shall not deviate more than 10 cm from
the theoretically correct position shown on the drawings. The inclination of the vertical pile
shall not deviate more than 1% from vertical. The Contractor shall provide suitable equipment
such as an inverted pendulum, to cheek the verticality of the boreholes during drilling and
prior to the concreting.
2.2.10. Boring
a)
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Method of excavation shall be proposed by the Contractor and approved by the
Engineer. Water or air jetting for boring of the piles shall not be allowed.
193
General Specification
b)
Boring Near Recently Cast Piles
Piles shall not be bored close to recently casted piles which contain non-hardened
concrete. Boring and excavation for a pile shall not be commenced until 24 hours
after completion of any pile within a radius of 6.0M.
c)
Temporary Casing
Temporary casing of approved best quality or an approved alternative method shall
be used to maintain the stability of pile excavations which might otherwise collapse.
Temporary casing shall be free from significant distortion. They shall be of uniform
cross-section throughout each continuous length. During concreting they shall be
free from internal projections aid encrusted concrete which might prevent the proper
formation of piles.
d)
Stability of Pile Excavation Using Drilling Fluid.
Where a borehole is formed without casing under water or using drilling fluid for
maintaining the stability of a boring, the level of the water or fluid in the excavation
shall be maintained so that water fluid pressure always exceeds the pressure exerted
by the soils and external ground water. The water or fluid level shall be maintained
at a level not less than 2M. above the level of the river water level or any artisan
pressure level.
In the event of a rapid loss of water or bentonite suspension from the pile
excavation, the excavation shall be backfield without delay aid the instructions of the
Engineer shall be obtained before excavation at that location is resumed.
e)
Disposal of Excavated Material
No excavated material shall be dumped into the river or any connecting. Excavated
material shall be removed from site and dumped at an approved location. The
Contractor shall be fully responsible for costs involved in removing the excavated
material to spoil.
f)
Pumping from borehols
Pumping from a borehole shall not be permitted unless a easing has been placed into
a stable stratum which prevents the flow of water from other strata in significant
quantities into the boring, or unless it can be shown that pumping will not have a
detrimental effect on the surrounding soil or property.
g)
Obstructions
Where boulders or other obstructions render it impossible to bore the pile,
excavation operations inside pile easing to remove obstructions shall be carried out
as directed by the Engineer. The removal of these obstructions is deemed to be
covered in the contract price.
h)
Unexpected Ground Conditions
The Contractor shall report immediately to the Engineer, any circumstances which
indicates that, in the Contractor's opinion, the ground conditions differ from those
expected by him from his interpretation of the site investigation reports and his
subsoil investigations.
i)
Boring Records
During the boring of the pile the Contractor shall compile a boring log indicating
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General Specification
depths and types of the various soil layers encountered. Disturbed samples sisal be
submitted to the Engineer if requested.
The Contractor shall take provisions for carrying out sampling and tests to check soil
strengths. The cost of the sampling and testing shall be included in the contract rates.
j)
Final Pile Toe Level
The final pile toe level shall be as indicated on the Drawing or as instructed by the
Engineer after due consideration of the Contractor's proposals, boring logs and test
results.
k)
Inspection and Cleaning Bottom of Excavation
The time between final excavation and bottom cleaning and the start of concreting
shall he reduced as much as possible and shall not exceed 6 hours. To achieve this,
the final 2M of excavation shall not start until all preparations for cleaning,
reinforcing and concreting are finalized. In case of unexpected delay the Contractor
shall dump sand or gravel in the borehole till 2M above toe level.
Immediately after excavation the bottom of the bore hole shall be carefully cleaned
of mud and sedimentation and other soft material.
The cleaning shall be made by an approved method. Sufficient notice of cleaning for
each individual pile shall be given to the Engineer to enable inspection.
Sedimentation tests (if required) shall be carried out by the Contractor in the
presence of the Engineer.
In case of boring without casing, the diameter of the boring hole for a each piles
shall be measured by calliper prior to the placing of reinforcement. The verticality of
boreholes will be checked Is directed by the Engineer. These measurements shall be
done by the Contractor using approved best quality and no reimbursement shall be
made.
2.2.11
Placing Reinforcement
The reinforcement shall be placed as indicated on the Drawings. Reinforcement in the form of
a cage shall be assembled with additional support, such as spreader forks and lacing,
necessary to form a rigid cage. Hoops, links or helical reinforcement shall fit closely around
the main longitudinal bars and be bound by them by approved wire, the ends of which shall be
turned into tile interior of tile pile or pour. Reinforcement shall be placed and maintained in
position.
The cover to all reinforcement shall be not less than 75
Joints in longitudinal steel bars shall not be permitted unless otherwise specified. Joints in
reinforcement shall be such that the full strength of the bar is effective across the joint and
shall be made in such a way that no relative displacement of the reinforcement occurs during
the construction of tile pile.
Joints in longitudinal bars in piles with tension (for instance for test loading) sisal] be carried
out by welding or method as approved by the Engineer.
2.2.12. Placing Concrete
a)
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Approval
195
General Specification
No concreting shall take place before the bottom of the excavation has been cleaned,
the borehole inspected and approval obtained from the Engineer.
Methods
The method of placing and the workability of the concrete, shall be such that a
continuous monolithic concrete shaft of the full cross sections is formed.
The concrete shall be placed continuously and without interruptions that allow the
previously placed concrete to set. In this respect the Contractor shall submit details
of his plans, standby paint etc. to be utilised in the event of an equipment failure.
The Contractor shall take all precautions in the mix design and during the placing of
the concrete to avoid arching of the concrete in a casing.
b)
Workability of Concrete
Slump measured at the time of discharge into the pile boring shall be minimum
150mm, maximum 200mm or as approved by the Engineer.
c)
Placing of Concrete under Water or under Drilling Fluid
Concrete to be placed under water or under drilling fluid shall be placed by tremie
and shall not be discharged freely into the water or drilling fluid.
Before the placing concrete, the Contractor shall ensure that Heavily contaminated
bentonite suspension, which could impair the free flow of concrete from the Pipe of
the tremie has not accumulated in the bottom of the hole.
As sample of the bentonite suspension shall be taken from the base of the boring
using an approved sampling device. If the specific gravity of the suspension exceeds
1.25 t/m3, the placing of the concrete shall not proceed. In this event the Contractor
shall modify the bentonite mud quality.
The concrete shall be placed in such a manner that segregation does not occur.
During and after concreting care shall be taken to avoid damage to the concrete from
pumping and de-watering operations.
The hopper and pipe of the tremie shall he clean and watertight. The pipe shall be
extended to the base of the boring. A sliding plug or barrier shall be placed in the
pipe to prevent direct contact between the fist charge of concrete in the pipe and the
water or drilling fluid. The pipe shall at all times penetrate the concrete which has
previously been placed and shall not be withdrawn from the concrete until
completion of concreting. The bottom of the tremie pipe shall be kept at least 1.5m
under the surface of the concrete. At all times a sufficient quantity of concrete shall
be maintained within the pipe to ensure that the pressure from it exceeds that from
the water or drilling fluid. The internal diameter of the pipe shall be not less than
150mm for concrete made with 25mm aggregate and not less than 200mm for
concrete made with 32mm aggregate. The internal face of the pipe of the tremie shall
be free from obstructions.
The Contractor shall maintain a continuous record of the volume of concrete used
related to the level of the concrete in the pile. any deviations from the theoretical, or
expected, volume/level relationship shall be immediately reported to the Engineer.
2.2.13
Extraction of Temporary Casing
a)
Workability of Concrete
Temporary casings shall be extracted while the concrete inside the pile retains
sufficiently workable to ensure that the concrete is not lifted.
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General Specification
b)
Concrete Level
During the extraction of the casing a sufficient quantity of concrete shall be
maintained inside the casing to ensure that pressure from external water or drilling
fluid is exceeded and that the pile is neither reduced in section nor contaminated.
The toe of the temporary casing shall be kept at least 50mm under the outlet of the
tremie.
c)
Vibrating Extractors
The use of Vibrating easing extractors shall be permitted.
d)
During the concreting and the pulling of the casing the reinforcement cage shall be
secured against uplift and the top shall be kept under close inspection.
e)
Supervision
The execution of tile Pile concreting shall be supervised by a qualified person of the
Contractor's staff, who will keep records on the relation between quantity of concrete
used, level of concrete and withdrawal of casing,
2.2.14
Temporary Support
The Contractor shall ensure that free standing piles are temporarily braced immediately after
casting to prevent loosening of the piles in the ground and to ensure that no damage resulting
from oscillation, vibration or movement of any free-standing pile length can occur.
2.2.15
Records
The Contractor shall keep records as indicated below for the installation of each pile and shall
submit two signed copies of these records to the Engineer within 24 hrs. The signed records
shall form a record of the work. The following data are requested:
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
k)
l)
m)
n)
o)
p)
q)
Contract
Pile reference number (Location)
Pile type
Nominal cross-sectional diameter
Date and time of boring
Date and time of concreting
River bed level at commencement of installation of pile
Working level
Pile toe level
River water levels
Pile head level
Length of temporary easing
Length of permanent casing
Soils samples taken and in situ tests carried out
Standing water level
Length and details of reinforcement
Concrete mix
r)
Volume of concrete supplied to pile and corresponding levels of concrete and
casings
All information regarding obstructions delays and other interruptions to the sequence
of work.
s)
2.2.16
Measures in Case of Rejected Piles
If any pile is found unsatisfactory in the opinion of the Engineer for Utilization in the structure
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General Specification
it shall be cut off below the pile cap if so ordered by the Engineer.
The pile shall be replaced as directed by the Engineer. All extra expenses shall be borne by
the Contractor and payment shall be made on the basis that no replacement pile had to be
provided for the unsatisfactory pile.
When the safe bearing value of any pile is found to be less than the additional piles shall be
installed as ordered in writing by the Engineer.
2.3.
Pile Load Test Work
The work shall include the application of test load (as per Schedule of Item) using Ancor piles, suitable
Beamd and Yokes, hydraulic Jacks etc. with suitable apparatus such as Pressure Gauge, Deflectometer
etc. for accurately measuring the test load and the settlement of the pile under each increment of load.
The load shall be kept for 48 hours. The work also include the cost of loading, carriage of load to
position, removal of the loads after completion of test, carrying and stacking those in neat measurable
stack as per direction of the Consultant/Engineer. The load test shall be performed following the
content of 3(c), 5(a), 5(b) of ASTM specification D1143-61 and the report shall be submitted as per the
same specification.
Load testing work of pile may also be done by any other alternate suitable method(s) and in that case
prior permission and approval shall be taken from the Consultant/Engineer but the Consultant/
Engineer is not bound to accept the alternate method of load testing work of pile.
2.4.
Dynamic Pile Load Test
In case any pile, during driving, goes below the required level, the driving may be suspended for 7
(seven) days and then driving will be attempted again and modified Heily's Formula shall be used for
evaluating the safe pile capacity where the factor of safety is 3.
3.
LEAN CEMENT CONCRETE WORK
The specification shall be the same as for R.C. works excepting that :
(i)
(ii)
(iii)
(iv)
(v)
No reinforcement will be used;
Proportion shall be as noted in Schedule of Items;
12mm down graded chips of Jhama bricks shall be used as coarse aggregate;
The curing shall be done for 7 days minimum;
Compaction of concrete may be done by wooden or steel tempers or rammers in lieu of vibrations;
In order to improve bond with masonry/concrete work coming above it, if required, the surface shall be
roughened before it reaches initial set, by scouring with the help of a pointed tool.
The size of groove shall be of section between 0.45cm2 and 0.90cm2 scouring shall be done in a pair of
orthogonal system of parallel lines spaced 100mm to 200mm and making 45o angle with either axes yielding a
mesh of 100mm to 200mm.
4.
BRICK WORK
General
The Bricks for use shall be regular in size and shape and shall be free from cracks and other structural defects.
The bricks shall be hand picked and stacked separately at least one day before use. Only after the stack is
approved by the Employer, the bricks shall be used in the works.
There will be average 10mm to 18mm thick mortar all around the brick. The proportion of cement-sand mortar
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General Specification
shall be as stated in the Schedule of Items.
All masonry work shall be laid by skilled workmen under adequate supervision and shall be laid true to lines and
levels with joints of uniform thickness and all surfaces true and corners straight and plumb.
Before use, bricks shall be cleaned and scrubbed. Any fungus and or moss grown on the surface, it shall be
cleaned by steel brush. Then those shall be soaked in clean tamarind water for at least 8 hours. Soaking shall be
discontinued 2 hours before use.
Sand shall be screened once and washed once immediately before use. The mortar shall be mixed in a mixer
machine.
Mortar shall be used up within 30 minutes of mixing the mortar. No retempering of mortar will be
allowed.
Water shall be of same quality as for making R.C.
Before laying bricks for a course, mortar of suitable consistency shall be laid with a large trowel over the
previous course in thickness more than horizontal joints. The bricks to be laid shall have the free and buttered
thickly and then shoved on the mortar bed pressing hard against the previously laid bricks in the same course so
that the horizontal and vertical joints are completely filled by flow of exposed surfaces of bricks shall be
meticulously avoided/cleaned. The proportion of cement and sand in mortar shall be as stated in the schedule of
items.
All horizontal joints shall be parallel and truly level. Vertical joints in alternate course shall come directly one
above other unless otherwise directed.
The top of everyday's work shall be covered with water proof covering to prevent rain water spoiling day's work.
No deductions will be made for flue, storm drainage, sewerage, electrical conduits and other utility pipe holes
for payment of the work. But those shall be provided by the Contractor true to plans and elevations.
The rate shall include the cost of erection and removing of scaffolding, trowel finishing the brick joints during
work and curing for 14 days complete.
5.
DOUBLE WYTHE BRICK WORK
The specification of this item of work shall be similar to that for `Brick work'.
The two wythes shall be constructed simultaneously. At no stage of progress of the tops of the two wythes differ
in level by more than 4 brick courses, that is the vertical spacing of ties. In this work, one wythe shall be built up
in stages equal in height of vertical spacing of ties. The other wythe shall also be built up in stages but always
lagging behind the former. When the leading wythe completes a height stage above the lagging one, its inside
face shall be plastered in cement-sand mortar. (The thickness of plaster and proportion of cement sand in mortar
shall be as stated in the schedule of items. The specification of plaster work shall be similar to that for cement
sand plaster work). The lagging wythe shall then be built up to reach the level of leading wythe. When the level
is reached the work will be shifted to leading wythe and the cycle shall be repeated until the full height of the
wall is reached.
The two wythes shall be bonded by expanded metal net tie or by "Z" tie made of 6mm dia m.s rod. The ties shall
be provided in every 4th horizontal course.
The details of ties to be used shall be shown in Drawings.
6.
BRICK BONDED CONCRETE WORK
The prepared sub-grade shall first be moistened with care so that it is not too wet. First class bricks that have
been soaked in water for at least 8 hours shall be placed in rows and columns in a manner so that the distances
between center lines of the interstices are 150mm in one direction and 275mm in the other.
Placing of concrete in the interstices and over the top shall proceed next. If at the time of commencement of
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General Specification
placing concrete the bricks are more than 2 hours out of soaking bath, they shall be remoistened with water in
position, care shall be taken that the remoistening is done in thin jets and that not much water leaves the bricks to
over wet the sub-grade.
Cement concrete shall be 1:2:4 mix. with medium sand as fine aggregate and 12mm down graded chips of jhama
bricks as coarse aggregate including breaking of bricks into chips. The work provided for paying single ordinary
brick flat with about 38mm gap all around to be filled in by concrete and then placing a topping concrete so that
overall thickness is as mentioned in the Scheduled of Items.
Interstices shall be carefully rodded. The top layer over the bricks shall be placed within half an hour of filling
the interstices, hence the progress between filling the interstices and laying of top layer will have a phase
difference of 15-20 minutes. The top of the work before the cover layer of concrete is placed shall not be
allowed to be soiled so that the bond between the concrete in interstices, of bricks and the cover concrete is not
reduced. The top layer of concrete shall be beaten by timber or any other means brought level or profile as
shown in the drawing. Immediately after finishing levelling and before drying up of the concrete, the top
surfaces shall be covered with cement powder strained through fine cloth and it shall be rubbed on the surface
carefully and repeatedly till the finished surface is very smooth, polished, plane and hard.
But in case where the surface will be without neat cement finishing work, the surface will be left rough. In both
the cases the concrete shall be cured for at least 14 days by stagnant water.
7.
R.C WORK
The item shall include cost of form work, provision for joints, dowels, recesses, grooves, holes, fixing of utility
pipes and other embedments curing etc. complete. The item shall include breaking of jhama bricks into coarse
aggregate of required sizes. Cost of reinforcement which is a separately payable item should not be included in
this item.
(a)
Water for Mixing Concrete
Water used in mixing concrete shall be clean and free from injurious amounts of oils, acids, alkalies,
salts, organic materials or other substances that may be deleterious to concrete or steel.
Where different materials of proportions are to be used for different proportions of the work, each
combination shall be evaluated separately.
(b)
Materials to be used
(i)
(ii)
(iii)
Cement
Fine Aggregate
Coarse Aggregate
:
:
:
Portland cement
A mixture of 67% medium sand and 33% coarse sand.
18mmn down well graded chips of jhama bricks or
boulders.
Grading requirement for Coarse Aggregate
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Size Num- Nominal size
50mm
ber
(Sieves with
square openings)
38mm
25mm
18mm
12mm
18mm
67
..
100
90 to
100
..
20 to 55 0 to 10
18mm to No.4
..
200
No.4
4.76mm
No.8
2.40mm
0 to 5
General Specification
The fine and coarse aggregate shall be screened at least once and washed at least once in clean water
immediately before use in works.
(c)
Concrete proportions and consistency
The leanest permissible mix proportion shall be as stated in the schedule of items. The consistency of
the concrete shall be such as to work readily into the corner and angles of the forms and around
reinforcement but without permitting the materials to segregate or excess free water to collect on the
surface.
The methods of measuring consistency of the concrete shall be such that the proportions can be
accurately controlled and easily checked at any time during the work.
The following slumps shall be used for different concrete members.
(i)
(ii)
(iii)
(d)
Beams and Lintels, Footings
Grade Beams
Roof slab, slabs, walls of water tank 25mm
Shelves
Minimum
Maximum
25mm
62mm
62mm
25mm
62mm
Strength Tests of Concrete
The strength of concrete 28 days, 150mm x 300mm cylinder, shall be as stated in the schedule of items.
Strength shall be the basis for acceptance. Each class of concrete shall be represented by at least five
tests (15 specimens). Three specimens shall be made for each test at a given age. The test shall have to
be carried out as per direction of the Employer but in no case more than three tests shall have to be
made for each 150 cubic yards of structural concreting.
Samples from which compression test specimens are moulded shall be secured in accordance with
"Method of Sampling Fresh Concrete" (ASTM C-172). Speciment made to check the adequacy of the
proportions for strength of concrete or as a basis for acceptances of concrete shall be made and
laboratory cured in accordance with "Method of Making and curing concrete compression and flexure
test specification in the field" (ASTM C-31) strength Tests shall be made in accordance with "Method
of Test for Compressive strength of Moulded concrete Cylinders (ASTM C-39).
The age for strength tests shall be 28 days. Additional tests shall be made at 7 days to obtain advance
information on the adequacy of strength development. The strength test of concrete cylinders is payable
under a separate item.
To conform to the requirement of this specifications, the average of any three consecutive strength tests
of the Laboratory cured specimen representing each class of concrete shall be at least 25 percent
greater than the specified strength, and not more than 10 percent of the strength tests shall have values
less than the specified strength.
(e)
Mixing and placing concrete
Preparation of equipment and place of deposits. Before concrete is placed, all equipment for mixing
and transporting the concrete shall be cleaned, all debris shall be removed from the space to be
occupied by the concrete.
Water shall be removed from the place of deposit before concrete is placed.
(f)
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Mixing of Concrete
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General Specification
Concrete shall be machine mixed at job-site.
(g)
Compaction
Concrete, during and immediately after depositing shall be thoroughly compacted. The compaction
shall be done by mechanical vibration subject to the following provisions :
Vibrators shall be of a type and design approved by the Consultant. They shall be capable of
transmitting vibration to the concrete at frequencies of not less than 4500 impulses per minute.
(h)
Curing
Concrete shall be maintained above 50oF and in a moist condition for at least the first 28 days after
placing.
(i)
Formwork
All form shall be of wood or metal and shall be, built mortar tight and of sufficient rigidity to Prevent
distortion due to the pressure of the concrete and other loads incident to the construction operation.
Forms shall be constructed and maintained so as to prevent warping and the opening of joints due to
shirkage of the lumber.
The forms shall be substantial and unyielding and shall be so designed that the finished concrete will
conform to the proper dimensions and contours. The design of the forms shall take into account the
effect of vibration of concrete as it is placed.
Forms for exposed surfaces shall be made of dressed lumber of uniform thickness, with or without a
form line of approved type, and shall he mortar tight. Forms shall be filleted at all sharp corners and
shall be given a level or draft in the case of all projection.
Metal ties or anchorages within the forms shall be so constructed as to permit their removal to a depth
of at least 50mm from the face without injury to the concrete. In case ordinary wire ties are permitted
all wires, upon removal of the forms, shall be cut back at least 6mm from the faces of the concrete with
chisels or nippers; for green concrete nippers are necessary. All fittings for metal ties shall be of such
design that, upon their removal, the cavities which are lief will be of the smallest possible size. The
cavities shall be filled with cement mortar and the surface left sound, smooth, even and uniform in
colour.
All forms shall be set and maintained true to the line designated until the concrete is sufficiently
hardened. Forms shall remain in place for periods which shall be determined as hereinafter specified.
When forms appear to be unsatisfactory in any way, either before or during the placing of concrete, the
Architect shall order the work stopped until the defects have been corrected.
The shape, strength, rigidity, water tightness and surface smoothness of re-used forms shall be
maintained at all times. Any warped or bulged lumber must be re-sized before being re-used. Forms
which are unsatisfactory in any respect shall not be re-used.
All forms shall be treated with oil or saturated with water immediately before placing the concrete. For
rail members or other members with exposed faces the forms shall be treated with and approved oil to
prevent the adherence of concrete. Any material which will adhere to or discolour the concrete shall not
be used.
Removal of forms and shores :
The supporting forms and shoring shall not be removed until members have acquired sufficient
strength to support their weight and the loads superimposed their safely. In no case may any forms be
removed until the time and sequence has been approved by the Engineer.
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All form work shall be removed without damage to the Concrete. The minimum time forms and
shoring to remain in place shall be as follows :
i.
ii.
iii.
iv.
8.
Beams and slabs spaning upto 6.10M
Beams and slabs spaning above 6.10M
Soffits of openings in wall
Column, wall and beam sides
:
:
:
:
14 days
20 days
14 days
48 days
REINFORCEMENT WORK
The item includes cutting into sizes, removal of rusts and loose scales, straightening, hooking and bending
according to design and drawing, carrying, placing in position, splicing and binding with 24 SWG Black mild
steel wire. The item also includes supply of binding wire.
Details of Reinforcement
9.
(i)
Hooks and bends shall conform to ACI Code 318-63 section 801.
(ii)
Cleaning reinforcement - Reinforcement shall be free from loose flakes, rust, mud, oil of other coatings
that will destroy or reduce the bond.
(iii)
(iv)
(v)
Placing of reinforcement shall conform to section 803 ibid.
Spacing of bars shall conform to section 804 ibid.
Concrete protection for reinforcement shall conform to section 808 ibid.
M.S STRUCTURAL WORK IN FRAME, SHUTTER AND GRILL WORKS
(a)
Preparatory work
The structural steel elements shall be cleaned of all loose scales and rusts by sand papering all
accessible parts of the body. If the elements get distorted before assembling they shall be straightened
in the shop by methods that will not injure it; it shall be kept straight during fabrication. Finished
members shall be free from twists, bends or open joints. If the elements have to be provided with holes,
the holes shall be drilled in the shop and not at the place of assembly. For large works templates shall
be made in order to control the profile and configuration of the assembly.
(b)
General
The joints of the elements shall meet without gap unless a gap is intended specifically. The planes of
the elements meeting at a joint which are required to be co-planer shall be accurately so. The weld
metals shall be deposited uniformly along the length of the containing the joint shall be rubbed out and
made smooth by grinding with power - grinders. Cutting of elements shall be done by steel hacksaw,
manual or power, but prior approval of the Consultant/University Engineer shall be obtained for this.
All cut edges exposed to view shall be ground even. If gas cutting is done the out edges shall be freed
from gouges by grinding.
(c)
Riveted and bolted Construction
Holes for rivets or bolts shall be 1.60mm larger than the nominal diameter of the rivet or bolt. If the
thickness of the material is not greater than the nominal diameter of the rivet or bolt plus 3.17mm, the
holes shall be either drilled from the solid, or sub-punched and reamed. The dia for all sub-punched
holes, and the drill for all sub-drilled holes, shall be at least 1.60mm smaller than the nominal diameter
of the rivet or bolt.
(d)
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Welded Construction
Surfaces to be welded shall be free from loose scale, slag, rust, grease, paint and any other foreign
material except that mill scales which withstands vigorous wire brushing may remain. Joint surface
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shall be free from fins and tears. Preparation of edges by gas cutting shall, wherever practicable, be
done by a mechanical guided torch.
Parts to be fillet welded shall be brought in as close contact as practicable and in no event shall be
separated by more than 5.76mm. If the separation is 1.60mm or greater, the size of the fillet welds shall
be increased by the amount of the separation. The separation between faying surfaces of lap joints on a
backing structure shall not exceed 1.60mm. The fit of joints at contact surfaces which are not
completely sealed by welds, shall be close enough to exclude water after painting.
Abutting parts to be butt welded shall be carefully aligned. Misalignments greater than 3.17mm. shall
be corrected and, in making the correction, the parts shall not be drawn into a sharper slope than 2
degrees (11.10mm in 300mm).
The work shall be positioned for flat welding whenever practicable.
In assembling and jointing parts of a structure or of build-up members, the procedure and sequence of
welding shall be such as will avoid needless distortion and minimize shrinkage stresses. Where it is
impossible to avoid high residual stresses in the closing welds of a rigid assembly, such closing welds
shall be made in compression elements.
In the fabrication of cover-plated beams and built-up members, all shop splices in each component part
shall be made before such component part is welded to other parts of the member. Long girders or
girder sections may be made by shop splicing not more than three sub-section, each made in
accordance with this paragraph.
All complete penetration but welds made by manual welding, except when produced with the aid of
backing material or welded in the flat position from both sides in square-edge material not more than
8mm thick with root opening not less than one-half the thickness of the thinner part joint shall have the
root of the initial layer gouged out on the back before welding is started from that side, and shall be so
welded as to secure sound meatal and complete fusion throughout the entire cross section. Butt welds
made with use of a backing of the same material as the base metal shall have the weld metal thoroughly
fused with the backing material. Backing strips may be removed by gouging or gas cutting after
welding in completed, provided no injury is done to the base metal and weld metal and the weld metal
surface is left flush or slightly convex with full throat thickness.
Butt welds shall be terminated at the ends of a joint in a manner that will ensure their soundness. Where
possible, this should be done by use of extension bars or run-off plates. Extension bars or run-of plates,
if used, shall be removed upon completion of the weld and the ends of the weld made smooth and flush
with the abutting parts.
The items of work shall also include painting the m.s. surfaces in 2 coats of synthetic enamel paint over
a coat of red lead primer.
10.
WOOD WORK
The timber shall be of species as specified in the schedule of items.
The dimensions shown in the design-drawings are finished dimensions prior to application of paint or varnish.
While sawing for sizes, allowance shall therefore be made for losses during sawing, working, painting and
finishing.
All wood work shall be neatly and truly finished maintain right angles and other angles accurately. Wood work
which will be exposed to view shall be accurately planed.
No filling or stopping of knots, cracks or other flaws shall be done by putting or other fillers. The Consultant
may, however, approve filling a neat square-cut hollow circumscribing the knot, crack of flaws by a plug of
exactly fitting size fixed with polyvinyl acetate adhesive but prior approval for this shall be taken.
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General Specification
Unless otherwise specified all joints shall be simple mortice and tenon joints with the ends of tenon exposed to
view. All mortice or scarfs shall fit truely and fully with full contact bearing and no filling shall be used. Holes of
correct size shall be drilled before insertion of nails or screws. The nails shall be in timber of the same quality as
that of the body unless otherwise permitted. All screws shall be dipped in oil before being inserted in the body.
The kind of nails and screws shall be subject to prior approval of the Employer. Driving in or starting in of
screws with a hammer shall not be allowed. If any undue shrinkage or warpage is noticed after the wood-work
has been erected, the work shall be pulled down and replaced.
All portions of timber built into or against or close to masonry or concrete shall be given two coats of hot
solignum, creosote or other wood preservative approved by the Consultant.
The direction of the grain shall be as shown in the design-drawings or as instructed by the University
Engineer/Consultant.
Finishing of the work shall be done by rubbing with sand paper of coarseness in the sequence of No.2, No.0 and
00 followed by hand rubbing with woolen rag.
11.
CEMENT SAND PLASTER WORK
(i)
(ii)
Sand shall be screened twice and washed at least once. It shall be absolutely free from acids, alkalies
and salts. The quality of water for mixing mortar shall be similar to that of R.C. work.
The proportion of cement and sand in mortar shall be as specified in the schedule of items using
medium sand.
(iii)
The bulk of each batch of mortar mixed, shall be such as can be exhausted in half an hour. The mixture
shall be turned over and over till the ingredients are thoroughly mixed.
(iv)
The surface shall be moistened with fresh water and shall be kept damp for 2 hours before the plaster is
applied.
(v)
The plaster work shall be so carried out that no segments, laps between them or patches are visible.
Preferably a wall or a ceiling shall be plastered in one operation with sufficient number of masons
working along side and working from top to downwards in walls. The plastered surface shall be true,
plane and plumb. All edges and corners shall be straight and squared. The surface of the plaster shall
be brought to a smooth finished with the help of steel trowels. The consistency of the mortar shall
neither be too stiff nor too fluid. The work shall be cured for 10 days, Chiselling and repairing of
cement plaster shall not be permitted under any circumstances. The thickness of plaster shall be as
mentioned in Bill of Quantities. The work shall also include providing of panel lines on plaster surface
as per drawing.
(vi)
Where so mentioned in the schedule of items there the plastering work shall be carried out in 2 layers
in the process as mentioned above, thickness of each layer being as mentioned in the schedule of items
except and provided that :
(vii)
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(a)
In both layers an admixture of "Pudlo" @4% by weight of cement shall be used.
(b)
The first layer shall be in the forms of scratch coat which shall be allowed to dry for a day
before the final coat is placed on it. The surface of the scratch coat shall be prevented from
getting covered with dirt or dust and shall be cleaned before the final coat is placed.
(c)
Immediately after finishing the final coat of plaster, its surface shall be covered with cement
powder strained through fine cloth and it shall be rubbed on the surface with the help of small
steel trowels working on the surface carefully and repeatedly and spreading of cement and
rubbing by steel surface shall be continued till the finished surface is very smooth, polished,
plane, hard and dry.
The mortar which was partially hardened or otherwise deteriorated shall not be used in work.
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General Specification
12.
BRICK LINING WORK
The specification of this item of work shall be same a that for "Brick work" vide item no.2 except and provided
that the work shall include formwork and cutting of bricks as necessary with the help of hacksaw and that the
thickness of brick lining shall be as stated in the schedule of items.
13.
RULED POINTING WORK :
The recess kept for pointing work during brick work shall be minimum 9.50mm and it shall be cleaned of all
dirts, dusts and extraneous matter and shall be washed with and soaked in clean water before the commencement
of pointing work.
The recess shall be completely filled with cement sand mortar in 1:2 proportion using medium sand and
admixture of black oxide 0.34 kg per bag of cement. The mixing of mortar shall be done as specified in cement
plaster work. During filling of the joint the mortar shall not be allowed to spread over the edges of the bricks.
When the cement mortar is thumb-print hard it shall be tooled with a non-staining tool of the special profile
instructed by the Employer.
The tooling shall be done neatly and skillfully so that the joint surface is true, hard, dense, smooth and glossy.
The rules shall be absolutely straight. The horizontal rules shall be continuous horizontal lines without break.
The vertical rules in alternate layers shall be in same vertical lines. The pointing work shall be cured for 7 days.
14.
ARTIFICIAL STONE FLOORING WORK
The floor shall be divided into panels, for providing contraction joints, as shown on the plan or decided by the
Consultant. The area of any panel shall normally not exceed 1.488 sqm. The temporary dividers may be of metal
strips or a wooden batten of true line and shape. The top of the dividers shall be perfectly level with level of the
finished floor desired. The sequence of filling in the panels should be on `checker board' plan. The casting of the
complementary set shall be done at least 48 hours after the first set is cast and dividers removed.
Extreme care shall be taken that the concrete or mortar of a panel does not `ride over' the top surface of the
adjoining panels previously cast.
The concrete work shall be done in accordance with the specifications for R.C. works except that no
reinforcement will be used in the work and that vibrators need not be used for compaction. Fixed proportion of
ingredients and not strength shall be the criteria. The proportion of concrete ingredients shall be 1 part cement,
1.5 parts coarse sand and 3 parts 9.50mm down graded chips of jhama bricks.
The concrete surface in sub-flooring shall be thoroughly scrapped to remove laitance, dirt etc. and washed
cleaned and soaked with water until no more water is absorbed.
The free water from the base being removed, a coat of mixture of cement and water, of the consistency of thick
cream, shall be brushed on the surface, just prior to placing the topping.
The ingredients shall be mixed with just sufficient water to obtain the plasticity required. Mixing for a larger
period will be preferred to adding more water to obtain this plasticity.
The concrete as prepared above, shall be laid immediately after the mixing is completed, on the freshly grouted
base. It shall be spread evenly and straight - edged carefully, and low place being filled, humps removed, and the
whole surface again straight - edged.
As soon as the layer is even, the surface shall be rapidly compacted by ramming or beating screeded to a
uniform line and level, and floated in neat cement finish using cement powder strained through fine cloth and
marble dust mixed in 1:1 proportion and it shall be rubbed on the surfaces with the help of small steel trowels
working on the surface. This trawling operation shall be repeated several times till the surface is hard,
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General Specification
impervious, smooth and nearly dried. The thickness of neat cement finish shall be 3.17mm (minimum).
Where specified in the schedule of items the top finish shall be done in neat cement finish only without
admixture of marble dust.
The finish shall be covered by burlap immediately after it has got the final set and shall be kept continuously
submerged under water for at least 21 days. The thickness of the floor finish shall be as specified in the schedule
of items.
15.
SKIRTING/DADO WORK IN CEMENT-SAND PLASTER
The specification for this item of work shall be same as that for cement-sand plaster work.
(a)
The proportion of cement-sand shall be 1:4 and sand to be used shall be coarse sand.
(b)
The plaster shall be laid in two layers. The first layer shall be in the form of a scratch coat which shall
be allowed for a day before the final coat is plastered on it. The surface of the scratch coat shall be
prevented from getting covered with dirt or dust and shall be cleaned before the final coat is plastered.
(c)
Immediately after finishing the final coat of plaster its surface shall be covered with cement powder
strained through fine cloth and marble dust mixed in 1:1 proportion and it shall be rubbed on the
surface with the help of small steel trowels working on the surface carefully and repeatedly (at least
four passes over the entire area) till the finished surface is very smooth, polished, plane and hard.
Where specified in the schedule of items the top surface shall be finished in neat cement finish only
without admixture of marble dust.
16.
TERRAZZO-IN-SITU WORK IN FLOOR
The sub-floor shall be cleaned of all liatance, dirt and extraneous mater. It shall be cleaned twice with clean
water till the sub-floor is spark-clean. The sub-floor shall be kept continuously moist for 4 hours before the
concrete bed is placed.
The floor shall be divided into panels for providing contraction joints as shown in the Drawings or specified by
the Consultant. Unless otherwise specified, the area of a panel shall not exceed 1.488 sqm. The temporary
dividers may be metal strips or wooden battens whose edges shall be straight, true and sharp. The top of the
dividers shall be perfectly level with the desired level of finished floor. The sequence of casting in the panels
shall be on `finished floor' plan. The complementary panels shall not be cast till the divider strips are removed
and 48 hours elapse since the casting of the adjoining panels. If the material for divider strip is absorbent it shall
be moistened or oiled with non-staining grease before the flooring may come in contract with it.
A bed of plain cement concrete shall be laid on the moist sub-floor. The proportion of mix shall be 1:2:4 using
medium sand and 18mm down chips of well burnt jhama bricks as coarse aggregate. Next, the topping course
proper shall be laid, The topping course shall be composed of marble chip and cement mixed dry in the
proportion 1:1 by volume in which water shall be added gradually in order to make the mix plastic but not too
wet. Colouring agent shall be used in proper proportion if coloured flooring is intended. The flooring shall be
white unless otherwise specified, be in two fractions, 2 parts 4.76mm down and 1 part 1.60mm down. The
thickness of topping shall be 9.50mm. The mixture shall be poured into panels formed by temporary strips along
contraction joints and it shall be rolled into a compact mass by using a heavy stone or metal roller until all
superfluous cement and water are extracted.
The quality of marble chips and marble powder shall be as stated in the schedule of item.
Where so specified grey cement shall be mixed with white cement in the proportion as stated in the schedule of
Items. The surface shall then be hand trowelled to an even surface flush with the top of the strips. The finished
surface shall show 70% marble granules. The floor shall be kept moist throughout these operations and when the
operations are complete, it shall be cured for at least 10 days.
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General Specification
When the floor is cured for at least 10 days, it shall be polished manually or with surface grinding machine. This
grinding is to remove laitance or loose material and to produce a smooth finish. The first grinding shall be done
with a coarse carborundum stone (80 Grit) and fine sand sprinkled ever the surface, using water freely. The floor
shall be cleaned twice with clean water after the first grinding is done. All pores and holes shall next be filled
with white cement grout. After 5 days the second grinding shall be done using grinding machine or manually
using a finer grain carborundum stone (120 Grit.). The surface shall then be cleaned twice using clean water and
a light grout of pure white cement shall be spread over the entire floor an be allowed to fill in all fine voids.
After the grout has hardened for 3 days, the surface shall be subjected to final grinding with machine or
manually, with carborundum stone 240 Grit. The floor shall be washed thoroughly after each grinding and in the
final grinding washing shall be done with hot water and pure soft soap.
After washing, cleaning and drying the floor after final grinding, oxalic acid shall be dusted over the surface
(0.30 kg over 9.3 cm2). The floor shall then be sprinkled with water and rubbed hard. This operation shall be
repeated till the surface has acquired the required gloss. The following day the floor shall be wiped with a moist
rag and dried with a soft cloth. A hot mixture of turpentine and bee-wax (3:1) shall then be applied to the surface
and thoroughly rubbed with hand and later again rubbed with clean cotton waste using 4 passes. This rubbing
will be continued till the floor ceases to be sticky. Best result will be obtained with a minimum of wax and
maximum of rubbing.
17.
ALUMINIUM WORK
Framing and Construction
Materials, hardwares, accessories and workmanship required for the job shall meet the latest applicable
requirements setforth for use in the commercial buildings with high performance by the Architectural
Aluminium Manufactures Association and the US Federal specifications:
Extruded sections for doors, windows, screens and fixed panels shall be of high quality 6063-T5/latest modified
aluminium alloy, 2mm thick and of required depth.
Aluminium facings/skins (both sides) for light cored flush doors shall be of 5005-B14/latest modified aluminium
alloy, anodizing quality and monolithic sheet.
All aluminium sections and facings shall be anodized with an anodic film of minimum 18 micrones to ensure
resistance to abrasion and weathering actions. The colour spectrum shall be dark bronze (ANOLOK-516/KE
Alloy medium bronze or approved best quality.
Overall thickness of flush door panels shall be 44.45mm and suitable for use in commercial buildings.
Head, sill and jamb members shall be of one piece construction. All joints shall be mechanically done square
(telescopic) joints and bedded in a polysulphide sealant. No mitred joints shall be accepted. No forced fittings
are acceptable.
Sills shall be of hi-bottom section.
Components, parts and accessories shall be of aluminium alloy, stainless steel or non-metallic materials which
will neither deteriorate nor promote corrosion and shall match with frames.
Screen frames shall recess into the window frames and be held in place with screen spreaders and thumb
fasteners and removable from inside.
Aluminium to aluminium contact between hardware parts or door/window members that move against one
another shall not be permitted.
Hardware
Rollers shall be long wearing nylon with stainless steel ball bearings concealed in frames of sliding sash.
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General Specification
Window locks shall be flush type as manufactured by Adams Rite Manufacturing company of Glendale,
California or approved best quality. It shall be spring loaded to provide automatic locking when closed.
Security locks shall be pin type mortice lock, 3 or 7 pins and adaptable for Master, Grand Master and Great
Grand Master keys closer's push/pull and kick plates shall have to match with the frames. Any other hardwares
to be incorporated in the work must also match with the frame.
Assembly and installation screws shall be stainless steel. Doors and Windows shall be installed in the building
with teflon injected expanding bolts.
Glazing
All glasses shall be fitted in the frames with nonsetting glazing mastic channel of required sizes.
Weather stripping
Polyprophylene/virgin vinyle weather stripping shall be integrated with all extrusions to avoid metal to metal
contract and give full protection against draughts and from buffeting.
Styles of all movable sash shall be provided with wool pile fabric weather stripping on both interior and exterior
faces to properly contact with main frame.
Sealants
Contact faces between aluminium frames and structural members shall be sealed with sealants like Dynaseal
W.100/Sikaflexal/Tremco brand sealants or approved best quality.
Drainage
Drainage holes shall be located at 610mm centres to ensure proper drainage.
Glass
Base glasses for all glazing work shall be Float/Plate glass whether they are clear , tinted, polished or tempered.
Tinted glass shall match dark bronze spectrum (ANOLOK-516/KE alloy Medium Bronze or approved best
quality.
18.
GLAZED TILE WORK
The tile shall be mettle glazed, waterproof, white, dust pressed with square edges. The tiles shall be 12mm thick.
No border edging or rounding pieces will be used. Length of each side of wall shall be filled by the tiles
completely. The cut sizes, if used at the ends shall be equal in size and as close to full size as possible by making
either the edge or the centre of tile to coincide with the vertical centre line of wall. The wall on which the tiles
shall be applied shall be kept moistened for 2 hours. Next the bedding mortar in 1:3 using medium sand shall be
applied. The size of the tiles to be used shall be as stated in the schedule of items. The joints in tiles shall be
pointed with white cement mortar unless otherwise specified.
19.
LIME TERRACING WORK
Stone lime shall be used for this work and the stones (quicklime) shall be slaked on the job. Under no
circumstances shall lime be procured in the slaked state. The terracing shall be done by lime concrete composed
of lime, surki and brick khoa mixed in the ratio 2:2:7 by volume unless otherwise specified. The brick khoa shall
be first class brick chips and shall be graded 20mm down. The thickness of lime concrete shown at different
points of the surface shall be provided accurately. If the thickness of lime terracing is not specified it shall be
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General Specification
50mm at drainage outlets with thickness increasing with increasing distance from it as required to provide
surface slope of 1:120. The platform on which the mixing will be done shall be level and even and the surface
impervious without any open joints. The platform shall be leaned thoroughly and on it the slaked lime and surki
shall be mixed dry in the requisite proportion using rectangular boxes as units by spading the mass at least 3
times. The brick khoa shall be soaked in water continuously for 48 hours before use.
The water-soaked khoa shall be spread to a uniform height over another platform which has been thoroughly
cleaned previously. The mixture of lime and surki shall then be spread over it uniformly in a thickness as
required by the proportion of the mix. The lime-surki mixture and the khoa aggregate shall then be mixed
together by means of spades. While mixing the materials water shall be added gradually in small quantities. The
materials mixed thoroughly till the mixture is uniform and for this purpose the entire mass shall be turned over
not less than 3 times. After the mixing is done it shall be allowed to stand for being tempered. After 40 hours the
concrete shall be turned over throughout its entire mass at least twice and during this spading also small
quantities of fresh water shall be added as needed for workability.
The concrete shall again be allowed to stand for being tempered. After 24 hours the mass of concrete shall be
spaded and turned over twice. It is now ready for laying.
The surface on which the lime concrete will be placed shall be cleaned and washed accompanied by scrubbing if
necessary. This surface shall never be used even partially as a mixing platform. The surface shall be well soaked
in clean water immediately before the concrete is spread over it. The concrete shall be laid in proper thickness
and slopes, a margin of 25% in thickness being allowed for settlement all over the surface and allowed to be
soaked in.
Beating shall now begin by two rows of beaters who shall traverse the length of roof backwards and forwards
while beating with wooden mallets. Beating shall continue until the mortar has almost set and the mallets
rebound from the surface, but shall not be for a period less than a week. The number of beaters shall not be less
than 3 for each 9.3 sqm.
Lime water to which molasses and conventional resins have been added @5% by weight shall be sprinkled at
intervals to keep the surface wet while being beaten. Special care shall be taken that no portion of the surface is
allowed to dry up even for a small period of time during the entire period of beating. No plaster shall be allowed
on the surface.
The mortar which comes up during beating shall be troweled on the surface to cover any blind spots and bring
the surface to some degree of polish. The surface shall be cured by impounding water for 14 days.
20.
PAINTING WORKS
The type of paint shall be as specified in the Bill of Quantities. The surface shall be rubbed clean with sand
paper. The cleaned surface shall be free from foreign materials. If there be any unevenness in the surface it shall
be made even by making good the surface defects in a manner approved by the Consultant. The surface shall be
allowed to be completely dry before the work is undertaken.
The floor, doors, windows, glazing and other members, which may get a splash of paint during the work, shall
be covered with the help of paper or any other suitable covering sheet so that the paint does not stain any part or
any member of the building not intended to be covered by the paint. If such staining takes place in spite of the
best precautions, the stain shall be forthwith removed.
The manufacturer's specification shall be meticulously followed except and so far as not modified by the
Consultant.
The colour of the paint shall be as selected and approved by the Employer.
Painting shall not be carried out in damp weather nor when weather is excessively hot and dry. No painting shall
be done on a surface having direct sun rays at the time of painting. The relative humidity shall be above 20%
and below 50% at the time of painting. No painting shall be done if there is a chance of rain, paint shall be
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constantly stirred while being applied, such stirring being done with a smooth stick and under no circumstances
with the brush.
The preceding coat shall be perfectly dry and all dust shall be removed and the condition of surface approved by
the Consultant before the next coat is applied. Each coat shall differ slightly in tint from the preceding one to
permit ready distinction of each coat, the last coat being of the tint required for the finished work.
Where brushes are used for applying paint they shall be as supplied or recommended by the manufacturers. The
brushes shall be washed in hot water after work each day and hung up to dry. Brushes clogged with old paint
shall not be allowed on the work.
All coats shall be spread as evenly and smoothly as possible by means of crossing and laying off. The final coat
shall be very carefully crossed and laid off so that the brush marks are not visible.
When using a brush to apply paint, the paint shall be applied from the ends of the hair, If the sides are used, the
application is not satisfactory. Brush shall be reversed at frequent intervals so that it wears down evenly. A free
easy stroke shall be the rule of applying the brush. Short and jerky strokes shall be avoided. Stretching the
strokes too far shall also be avoided.
In brush painting, brushes shall be applied quickly and boldly leaving non dry edges. The brush shall be dipped
in paint and stroked horizontally on the wall, then immediately stroked up and down and stepped. Two workers
shall work on a wall together, one working from the ceiling and down-words as far as he can reach and the
second following him in applying the paint in the lower height of the wall. No patchy overlaps shall be allowed
under any circumstances.
Before starting work enough paint shall be mixed to finish one room. Each room shall be finished in one
operation and work shall not be started in a room so late as can not be finished the same day.
When paint is not in use, its containers shall be closed airtight. When painting is completed the surface shall be
of uniform colour free from blotches, lines or cut-shades and shall present a smooth, regular and even surface
such as will neither cut nor come off on the fingers when rubbed.
The Contractor shall remove with turpentine, or by other approved method, all defects and leave the work in
perfect order after removing all stains, smears splashes and dropping from floors, doors, windows glazing,
furniture etc.
Number of coats of paints to be applied is specified in the Bill of Quantities. The paint shall be of BERGER
BRAND/approved best quality by the Consultant. The priming coat shall be as recommended by the
manufacturers. Under no circumstances shall the surface be primed with whiting or lime. The items shall also
include all scaffolding work.
21.
WHITE WASHING/COLOUR WASHING WORK
Before the white wash is applied, the walls are to be thoroughly cleaned down and made free from all foreign
matters. When the wall gets dried, it will be again washed with tamarind solution in concentration approved by
the Consultant. When the wall is dry again, it is ready to receive the white wash.
The wash is to be composed of fresh stone lime and shell lime slaked on the spot in the proportion of two parts
of the former to one part of the latter. The slaked lime is placed in tub nearly full of water and is then mixed and
stirred until it attains the consistency of thin cream. When sufficiently mixed, it is to be strained into earthen pots
through coarse cloth. Gum Arabic in the proportion of two chhataks to thirty seerts of lime shall be added to the
strained wash and the whole shall then be boiled together. It is now ready for use.
White wash shall be laid on the walls vertically and horizontally alternately. Each coat shall perfectly dry before
the succeeding one is laid over it.
In case of colour wash work, the cream for colour wash shall be prepared by simply mixing the requisite
coloring material (to be approved by the Consultant) to the cream of white wash. The colour wash shall be laid
over a priming coat of white wash.
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Number of coats of white wash/colour wash shall be as stated in the Bill of Quantities.
The items shall also include all scaffolding works.
B. PLUMBING WORKS
1.
SCOPE OF WORKS
As for Civil items of work, each item of works shall include furnishing by the Contractor of all plants, machinery
and equipment, fuel, materials and labour. It shall also include cost of all auxiliary and secondary works to be
done for executing the item. For example, the item for laying drainage pipes shall include all excavation
including shoring and dewatering if necessary, painting, laying jointing, fitting, supplying joints and all
connections, e.g. bends, Y-junction branches, supplying, sealing, providing concrete bed as per specification
carrying out tests for defective work, filling the trenches with earth, sand, formwork for concrete bed etc. making
holes in masonry or concrete works for passing through them where needed and making good area of the hole
outside the laid pipe; lintel in the wall above the pipe if the hole is wider than 150mm; testing the completed
item of work etc. complete. For second example, an item for supplying and installing galvanised iron service
pipe for water supply shall include (i) reduction joints at either ends and in intermediate locations if needed, (ii)
applying and providing bends, elbows, tees, unions, plugs and any other connections and junctions necessary,
(iii) arrangement for securing and supporting them throughout their length as per approved design and methods,
(iv) arrangement for embedment in masonry or concrete works as the masonry/concrete work proceeds and/or
cutting grooves, recesses, holes etc. as needed and surrounding the pipe by concrete/mortar as per approved
design, making good the surface of walls, floors or ceiling to the usual surface finish, (v) testing of all defective
works, (vi) supplying and providing gate and screw down valves, (which will be payable under separate items) at
each central position unless otherwise specified etc. complete.
2.
GENERAL
The work shall conform to National Plumbing Code (ASA A40.8-1955) published by the American Society of
Mechanical Engineers unless modified hereunder. General arrangement of drainage and plumbing as shown in
Drawings shall be faithfully observed. If any change is necessary for any reason, the Contractor may invite
notice of the Employer to the matter but shall not make any alteration himself.
3.
APPROVAL OF MATERIALS
Inspection and approval of the Employer shall be sought and secured by the Contractor before the pipes and
other materials are used in work. Rejected pipes or materials shall be separately stored and removed from site
within 24 hours of being asked for removal.
Pipes shall be kept absolutely free from earth, debries, superfluous cement and other obstructions during laying
and until the completion of contract.
4
GRADIENTS
Drain pipes shall be laid to following gradients unless otherwise specified or shown in the Drawings :
5.
Size of Pipe
Soul Pipe
Rain or waste water pipe
100mm dia
150mm dia
225mm dia
1 in 40
1 in 60
1 in 100
1 in 60
1 in 90
1 in 150
JOINTING
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General Specification
(i)
Cast Iron pipes :
Unless otherwise specified, the jointing shall be done as for R.C. pipe but no preliminary wetting is
necessary.
(ii)
Asbestos cement pipe : (Used as drain pipes)
The joints of asbestos cement pipes shall be as for R.C. pipes.
(iii)
Galvanised Iron Pipes :
The pipes, sockets and fittings shall be cleaned first and allowed to dry before use in the work. The
joints shall be made water tight using hemp yarn soaked in China Lacquer. The tightening shall be done
perfectly by Torque wrench.
(iv)
Reinforced Concrete Pipes :
Spigots and sockets shall be thoroughly wetted by water at first hemp yarn soaked in cement grout shall
be caulked turn by turn upto 12mm depth on either side of mid length of socket ensuring that the
spigots and sockets are co axial and that the hemp-seal would not permit the cement sand mortar
packing the reach inside the pipe hollow. The remaining space shall be filled up by cement sand mortar
in 1:2.5 proportion using medium sand. The filling of the mortar shall be done by small thin trowels
and in small batches. A fillet shall be formed all around the pipe at the joint at an angle of 45o. The
joints shall be cured for 14 days.
(v)
P.V.C. pipes :
The joint of PVC pipes shall be sealed with the help of Plastic Glue.
6.
TRAPS AND STRAINERS
Lavatory basins, water closets, and urinals shall be fitted with suitable traps with water seals. The collection
point in toilet room floor, collecting the waste water shall be fitted with 10mm cast iron strainer with 4.76mm to
6mm wide slits and 10mm wide ribs and provided with a flat-bottom trap (trap is a separate item).
The rain water stacks shall have 300mm dia C.I. M.S. sheet Bell-mouth circular cone with 6mm thick C.I.
hemispherical grating of M.S. Rod mesh at the top. (Bell-mouth circular cone and Hemispherical Grating are
payable under separate items).
If for some unavoidable reasons, flat strainers are used with prior approval of the Employer, the available inlet
area shall be double the pipe area. The strainer shall be firmly secured to the pipe by means of bell and spigot
joints or 4 nos. nuts and bolts of 6mm dia. The thickness of cast iron strainers shall be 6mm; the strainer holes
shall not be more than 12mm long, its width shall be more than 9mm but less than 8mm; the width of metal
between holes shall not be less than 6mm.
7.
ANTI-SIPHON/VENT PIPE
Anti-siphon pipe or by-pass vent pipe shall be used to serve water closets which drains to a soil stack serving
water closets in a higher floor(s). The anti-siphon pipe shall be connected to the soil pipe at least 0.76M above
the highest floor served by the soil stack.
8.
VERTICAL EXTENSION OF STACKS
The soil stack, vent stack and waste water stack shall be carried to at least 0.61M above roof finish work, unless
otherwise shown in the Drawings.
9.
BRANCH DRAIN PIPE AT FLOOR LEVELS
If the water from lavatory, wash basin, kitchen sink or bath tub is not connected to a waste stack or inspection pit
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General Specification
directly but, drained through a floor trap, 50mm dia C.I. pipe laid at a slope 1:50 shall be used as branch drain
pipes unless otherwise specified or approved. These pipes shall be embedded in the floor slab which may be
thickened for this purpose. The extra thickness of floor slab on this account will be paid for under the item of
floor slab, prior authorization of the Employer shall be secured in the matter.
10.
PIPES TO BE CONCEALED
All work shall be concealed and embedded in wall, floor, roof and below grade or ground unless otherwise
specified. The routing of the plumbing lines concealed in the building must precede simultaneous with the
construction of masonry work phase by phase. In the straight reaches in brick walls, the alternative of leaving a
recess in the wall of future insertion of the pipe may be allowed.
Access and inspection doors and covers shall be provided in all bends and junctions. These covers shall be
neatly provided and housed in the surface of the wall opposite to one facing the pipe.
In brick walls, the pipes shall be surrounded by concrete in 1:2:4 at least 38mm thick, all around them, the
coarse aggregate of the concrete being 10mm down size of Jhama brick chips and fine aggregate is medium
sand. All pipes except G.I. pipes less than 38mm dia when embedded in walls, shall be located in the Midthickness of wall unless otherwise specified or shown in the Drawings.
11.
PIPES TO BE SUPPORTED
If a pipe is embedded in wall with insufficient cover (less than 38mm) or if it is carried exposed, it shall be
supported by clamps and nails/nuts and bolts according to approved designs/methods. The distance between
supports shall not exceed 0.91M and the strength of each anchore shall not be less than that of a 10mm φ U-bolt.
12.
PROVISION OF LINTELS
If holes or grooves or partial pulling down of masonry or concrete work requires, according to the advice of the
Employer a lintel above it shall be provided by the Contractor at his own cost. The design and details of lintel
shall be as prepared or approved by the Consultant.
13.
EXCAVATION
Excavation of trenches for drains shall be made true to drawing and gradient. Over-excavation shall be avoided.
If over-excavation is done, this shall be filled up by the Contractor at his own cost with 1:5:7 cement concrete in
jhama chips and medium sand. If during excavation existing utility lines are exposed they shall be well secured
according to Employer's instruction. Care shall be taken for securing the utility lines and it will be paid for
separately. The width of the trench shall be at least 0.36M grater than the diameter of the pipe. Any shoring and
dewatering required during excavation shall be done at the Contractor's own cost. Before laying the pipes,
inspection and approval of the Employer shall be sought and secured by the Contractor.
All excavated materials shall be deposited away from the edge of the trance keeping at least 0.46M margin
concrete bedding of the pipes and joints and filling of the trench shall not commence till the drain pipes are
inspected and approved by the Employer. A depth of 0.30M above the top of the pipes shall be filled by hand
packing of selected soil out of the spoils. It shall be watered liberally and compacted with great care.
In selecting the soil for filling, all lump and clods larger then 25mm size shall be powdered or avoided. The
filling above this 0.30M shall be done in the usual way as specified under side filling of trenches. If grass
covered soil is removed during excavation of trenches. If grass covered soil is removed during excavation of
trenches, the top grass-bearing layer shall be separately preserved and replaced after filling the trench and nursed
till the original grass cover is restored and this work of preservation of grass top and re-laying will not be paid
for separately, its cost being deemed to have been included in the rate for pipe laying, surplus spoils of
excavation shall be disposed according to the instruction of the Employer but if the lead exceeds 152.44M
and/or if the materials is used for compacted fill, it shall be paid for as an item for excavation and/or compacted
fill.
14.
BENDS AND JUNCTION
No bend or junction shall be used in the buried drain pipes except at inspection chambers. All junctions shall be
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oblique.
15.
TESTING
Immediately after the drains are laid and jointed but before bedding in concrete they shall be inspected, tested
and passed by the Employer as satisfactory. The testing shall be done by water pressure for a head 3.05M more
than the highest point. Testing may be done section by section. The drain shall not be walked over before
concrete bedding is placed.
16.
BEDDING AND ENCASING DRAIN PIPES
The trench bottom shall be rammed and compacted to the satisfaction of the Employer. The drain pipes shall be
laid and supported on false supports. The jointing shall then be done and after the pipe network is tested under
pressure and approved by the Employer the concrete bed in 1:3.5:5.5 using 18mm down jhama brick chips and
medium sand shall be placed. The width of the bed at the bottom will be 350mm wider than the internal diameter
of the pipe.
The side slopes will joint the edge of the bottom of concrete bed and the pipe tangentially. The depth of concrete
bed shall be 100mm minimum below the pipe and shall be increased at joints as needed to maintain 100mm
minimum from socket surface. The concrete bed shall be cured for 10 days.
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Section – 8 Particular Specifications
1.
Compressive strength of 1st class bricks and Picked Bricks shall be tested 5 nos for every 1.00 lakh of 1st Class
Bricks / Picked supplied.
2.
Sieve analysis to find out Fineness Modulus of Medium / coarse sand shall be tested 3 samples for every 5000
cft of medium / coarse sand.
3.
Bending and yield strength of M.S. Bars shall be tested 3 pieces (each 1M long) of each diameter of M.S bar
provided the contractor supplies M.S. bar from same manufacturer. If M.S. bars are procured form different
manufacturers, then each lot shall be tested separately.
4.
One bag of cement (packed condition) shall be tested for compressive strength of 2 days, 6 days, 27 days in
water for same brand of cement.
5.
A set of 3-concrete cylinders (4” dia x 8” height) shall be tested for compressive strength for each category of
R.C.C. member.
Al the test shall be performed at the Laboratory approved by the University Engineer.
SIGNATURE OF THE TENDERER
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Section – 9
Drawings
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