ELECRTRIC WORK
1.0
SPECIFICATIONS FOR ELECTRICAL WORKS STANDARDS
Following IS specification Standard and rules will be applicable.
IS No.
DESCRIPTION
IS 2705
CT for measuring and protection
IS 373
Bus bar arrangement and marking
IS 1248 - 1958
Meter (measuring)
IS 3072 - 1975
Installation of Switch gear
IS 3043
Code of practice for earthing.
IS 8106 - 1966
Selection, Installation and
maintenance of fuses upto 650V
IS 8828 - 1978
Marking and arrangement of switch gear
Bus bar main Connectors and auxiliary
wiring.
IS 9926 - 1981
Cubical Board.
IS 1554
Insulated conductor rating.
IS 1753
Enclosed distribution switchboard and
cutout for Voltage not exceeding 100 V.
IS 961
Miniature circuit breaker.
IS 732
Fuse wire use in rewirable type electric
fuses upto 650V.
IS 1646
PVC insulated electric cable heavy-duty.
IS 1653
Aluminium conductor for insulated cable.
IS 961
Recommended current rating for cable.
IS 732
Code of practice for electrical wiring
installation system Voltage not exceeding
650 V.
IS 1646
Code of practice for wire safety of building
(general) Electrical installation.
IS 694
PVC insulated cables (wire).
IS 2509
Rigid non metallic conduits for electrical
wiring. IS 6946
Flexible (playable)
non
metallic
conduit
for
electrical
Installation.
IS 1293
Three pin plugs and sockets.
IS 818
Conductor for insulated electrical cables
and flexible codes.
IS 9537-1980
Specification for conduit for electrical
installation.
IS 3419
Accessories for non metallic conduit for
electrical wiring.
IS 3854
Switches.
IS 6538
Plugs.
IS 2834 - 1954
Capacitor.
IS 1913 - 1969
General safety requirement for lighting
fitting.
IS 2944 - 1969
Code of practice for lighting public
thorough fares.
IS 3528
Water proof electrical lighting fitting.
IS 3553 - 1958
Water tight electrical lighting fitting.
IS 1229 - 1958
Mild steel tubular and other wrought
steel pipe fitting.
IS 2149 - 1970
Luminaries and street light.
IS 9224
HRC fuses having rupturing capacity of
90 KA.
IS 2312 - 1967
Exhaust Fan.
IS 374 - 1976
Class – I Ceiling Fan.
NOTE :
All codes and standards means the latest where not specified
otherwise installation shall generally follow the Indian Standard
codes of practice in the absence of corresponding Indian Standards.
PLEASE FOLLOW :
Indian Electricity Act of 1910 and rules issued there under revises
upto date.
Special attention should be given to rule No. 50.
Regulation for electrical equipment in building issued by the Bombay
Regional Council of Insurance Association of India.
INTERNAL WIRING :
1.0
SCOPE :
This section covers, definition of point wiring system of wiring,
system of wiring and supply, installation, connection, testing
and commissioning of point, wiring for light point, ceiling fan
points, exhaust fan points, convenience socket, outlet points,
power socket outlet points, bell outlet points etc., including
fixing of light fixtures ceiling fan, exhaust fan, wall fan, bell etc.
2.0
STANDARDS :
The following standard and rules shall be applicable.
IS 732
Code of practice for electric wiring installation
(system voltage not exceeding 650 V).
IS 1646
Code of practice for fire safety of buildings
(general electric installation).
IS 1653
Rigids steels conduits for electric wiring.
IS 2667
Fitting for rigid steel conduit for electrical wiring.
IS 3480
Flexible steel conduits for Electrical wiring.
IS 3837
Accessories for rigid steel conduit for electrical
wiring.
IS 694
PVC insulated cables.
IS 2509
Rigid non metallic conduits for electrical wiring.
IS 6946
Flexible (pliable) non metallic conduits for electical
Installation.
IS 1293
3 - Pin plugs and sockets.
IS 8130
Specifications of conduits for electrical.
IS 3854
Switches for dogmatic purpose.
IS 3415
Fittings for rigid non-metallic conduits.
IS 4648
Guide for electric layout in residential building
Indian Electricity Act and Rules.
Regulations for the electrical equipment in buildings issued by
the Bombay Regional Council of Insurance Association of India.
All standards and codes mean the latest.
3.0
POINT WIRING :
A point shall consist of the branch wiring from the Main Light
board together with a switch as required, including the ceiling
rose or pendant holder or swan holder, or ceiling fan box or
socket or suitable termination. A point shall be including in
addition, the earth continuity conductor/wire from the
distribution board to the earth pin/stud of the outlet/switch
box and to the outlet points.
The points wiring shall be carried out in the under mentioned
manner.
3.1. Supply, installation, fixing of PVC conduits with necessary
accessories, junction / pull / inspection / switch boxes and
outlet boxes.
3.2. Supplying and drawing of wires of required size including earth
continuity wires of required size including earth continuity wire.
3.3. Supply, installation and connection of flush type switches,
sockets, cover plates, switch plates, can fixing fan regulator etc.
3.4. The point shall be complete with the branch wiring form the
distribution board to the outlet point, through switch board,
conduit with accessories junction, pull, inspection boxes control
switch, socket, outlet boxes, ceiling roses, bottom / swan
holder, connector etc.
4.0
SYSTEM OF WIRING :
Unless otherwise mentioned on the drawings, the system of
point wiring shall be as follows:
The system of wiring shall consist of single core, PVC insulated
650 / 1100 Volt grade standard copper conductor wires /
cables laid through concealed or exposed PVC conduits as
directed.
5.0
Conduits shall be concealed / embedded in slab / walls / floor
in all the area except where specified as surface mounted in
mechanical and plant room area rigid non metallic PVC conduit
shall be used for concealed / embedded installation while steel
conduits shall be used for our face installation and shall have
stove enable finished surface except installation in damp / wet
area, the steel conduit shall be G.I. conduits.
6.0
Price to laying of conduits the contractor shall submit for
approvals the shop drawing for conduit layout indicating the
out of the conduits number and size and location of switch
boxes number and size of wires pulled through each conduit
and all other necessary relevant details.
Only after the
drawings are approved the contractor shall proceed the work of
laying of conduit.
7.0
MATERIALS :
7.1. P.V.C. CONDUITS
All non-metallic PVC conduits shall conform to IS : 9537. The
conduit shall be plain end type as specified in IS : 9537 and
shall be used with the corresponding accessories (refer IS : 419
specification for fittings for rigid non PVC metallic conduits
shall be rigid unplasticised heavy gauge having 1.8mm wall
thickness upto 19 mm diametre conduit and 2.0mm wall
thickness for all sizes above 10mm diametre.
7.2. Conduits shall confirm to IS : 1653 finished with galvanized or
stove enameled surface. No steel conduit less than 19mm in
diametre shall be used. Conduit shall be solid drawn of lap
welded type, with minimum wall thickness up to 19mm
diameter and 2mm wall thickness for conduits having 25mm
and above diametre.
The conduits shall be delivered to the site of construction in
original packing and each length of conduit shall bear the label
of manufacturers.
The conduit accessories such ad bends, coupling etc., shall be
conforming to the relevant Indian Standard Specifications.
7.3. BOXES :
All the boxes for switches, sockets and other receptacles,
junction boxes, pull boxes and outlet boxes shall be fabricated
from 2.0mm thick mild sheet duly painted with two coats of red
oxide and then two coats of enamel paints the client. The boxes
in contact with mild steel and hot dip galvanized after
fabrication. Separate screwed earth terminal shall be provided
in adequate number of knock out holes of required diametre for
conduit entry. Switch boxes to receive switches, socket outlet,
telephone outlet fan regulators, etc., shall be fabricated to the
approved shape size to accommodate all the devices without
overcrowding outlet boxes to receive ceiling fan shall be fitted
with adequately sized rod / hook to fix ceiling fan. The boxes
shall be of a minimum depth of 65mm.
Boxes installed for concealed wiring shall be provided with
suitable extension rings or plaster covers as required. Boxes for
use in masonry block or tiles wall shall be square cornered tile
type or standard boxes having square cornered tile type covers.
These boxes shall be installed in the center of the masonry
block or tiles.
Cast metal boxes installed in wet locations and boxes installed
flush with the outside of exterior surface shall be gasketed.
7.4. COVER PLATE :
The cover of the boxes to receive outlet points shall be of best
anodized sheet cut to shape and size as approved by the client.
For factory building shall be covered with standard M.K. plates
and junction boxes, pull boxes, boxes shall be provided with
3mm thick anodized sheet cover.
7.5. CABLES :
The cables shall confirm to IS : 694 for al internal wiring PVC
insulated cables of 650 / 1100 Volts grade single core shall be
used.
The conductors shall be plain annealed copper conductors
complying with IS : 1554.
The conductors shall be circular standard copper conductors.
The minimum number and diameter of wires for circular
standard conductor shall meet the requirements set out the
relevant Indian Standards.
The installation shall be PVC compound complying with the
requirements of IS : 694. It shall be applied by an extrusion
process and shall form a compact homogeneous body.
The thickness of PVC insulation shall be as set out in the
relevant standards.
The cores of all cables shall be identified by colors in
accordance with the following sequence.
Single phase
Three phase
Neutral
Earth
-
Red
Red, Yellow, Blue
Black
Green or green / Yellow
Means of identifying the manufacturer shall be provided
throughout the length of cable.
Unless otherwise specified in the drawings the size of the cables
used for internal wiring shall be as follows :
In case of circuit wiring for lights, exhaust fans, ceiling fans,
bell, convenience socket outlet points :
1.5 Sq.mm
1.5 Sq.mm
-
From DB to switch boards.
From switch boards to outlet points.
In case of power socket outlet circuit having not more than two
15 Amps power outlet.
4.0 Sq.mm
2.5 Sq.mm
-
From DB to first power outlet
From first power outlet to second power
outlet.
In case of power socket outlet circuit having single 15 Amps
power outlet (like water heater).
4.0 Sq.mm
-
From DB to power outlets.
In case of 15 Amps power outlet for window Air-conditioner or
other like wise appliances.
4.0 Sq.mm
-
From CB to power outlet.
The earth continuity conductor shall be similar to circuit cables
and shall be drawn through conduit along with other circuit
cables. The size of the earth continuity conductor shall be as
under.
MINIMUM SIZE OF EARTH CONTINUITY CONDUCTOR NOT
FORMING PART OF THE SAME CABLE AS THE ASSOCIATED
CIRCUIT CONDUCTOR:
Nominal Cross - sectional
Nominal Cross-sectional
Area of largest Associated
Copper
Area of earth Continuity
conductor
Circuit conductor
2 in mm.
1.5
2.5
4.0
6.0
10.0
16.0
25.0
35.0
50.0
2 in mm.
1.0
1.5
2.5
2.5
6.0
6.0
16.0
16.0
16.0
Separate circuit shall run for each water heater, kitchen
equipment, window air conditioner and similar outlets at
location as shown on drawings.
7.6.
SWITCHES :
Switches shall conform to IS : 3854, IS : 1293 and IS : 4015.
The switches shall be single pole, single or two way and shown
on the drawings or as specified. They shall be of the molded
type rated for 250 Volts, and of full 5.15 Amp capacity. They
shall be provided with insulated dollies and cover.
The switches shall be rocket operated with a quite operating
mechanism with bounce free snap action mechanism enclosed
in an area resistant chamber. The switches shall have pure
silver and silver cadmium contacts. The switches shall be flush
modular type. The make of the switches shall be as indicated
in the drawings of BOQ or as suggested and approved by the
client.
The switches installed in outdoor area shall be
industrial, metal clad type and shall be provided in weather
proof enclosures, complete with weather proof gasketed covers.
7.7.
SOCKETS :
The sockets shall conform to IS : 1293. Each socket shall be
provided with control switch of appropriate cating. The sockets
shall be moulded type rated for 250 V and either of full 5 Amp
or 15 Amp capacity as mentioned on the drawings.
Sockets shall be three pin type third pin long connected to earth
continuity conductor. The socket shall be flush, modular type.
The sockets installed in machine room, plant room or wet /
damp area shall be metal clad weather proof type. The finishing
and make of all the sockets shall be same as light switch. The
socket shall have fully surung socket contacts and solid brass
shrouded terminals to ensure positive electrical connections.
The sockets shall be provided with automatic shutters which
opens only when earth pin of the plug inserts in the socket.
The socket shall be provided wire three pin plug top suitable to
the socket and of the same make as socket.
7.8.
LIGHTING FIXTURES, FANS, EXHAUST FANS :
The light fixtures and fittings shall be assembled and installed
in position complete and ready for service in accordance with
details, drawings, manufacturer’s instructions and to the
satisfaction of the client. Pendant fixtures specified with over
all seam lengths are subject to change and shall be checked
with conditions on the job and installed as directed.
All
suspended fixtures shall be mounted rigid and fixed in to the
approval of the client. Fixtures shall be suspended true to
alignment, plumb in level and capable of resisting all lateral and
vertical forces and shall be fixed as required.
All suspended light fixtures, fans etc., shall be provided with
concealed suspension arrangement in the concrete slab proof
members.
It is the duty of the contractor to make these
provisions at the appropriate stage of construction. Exhaust
fans shall be fixed at a location as shown on the drawings or as
directed at later stage. They shall be poluged to a socket outlet
installed at a convenient location near the fan. All switch and
outlet boxes for fans and light fittings shall be bonded to earth
with 1.5mm PVC insulated copper conductor wire or equivalent
standed copper wire shall be connected to all fixtures through
connector blocks. Wires brought out from junction boxes /
outlet boxes shall be fixed to the junction / outlet boxes and at
the fixtures with brass bush and double check nut. The G.I.
flexible pipes, wherever used shall be of make and quality
approved by the client.
8.0
INSTALLATION :
8.1
CONCEALED WIRING SYSTEM WITH RIGID PVC
CONDUITS
Rigid PVC conduits shall be used for concealed wiring system.
The conduits shall be concealed in the concrete slab, floor,
walls, beams, columns etc.
8.1.1.
FIXING OF CONDUITS
Conduits embedded in concrete shall be installed in the frame
work before pouring concrete. The conduits shall be installed
above the bottom reinforcing bars, and shall provide positive
wire fasting of the conduit t one meter but on either side of
couplers or bends or outlets/pull/junction bodes or similar
fittings proper hold fast shall be fixed at a distance of 30cm
from the center of such fittings. Conduits embedded in the wall
shall be fixed inside the chase. The chase in the wall shall be
neatly made and be of ample dimensions to permit the conduit
to be fixed in the manner desired. In the case of building under
construction their construction and shall be filled up neatly
with cement mortar 1:4 after erection of conduit and brought to
the original finish of the wall. Cutting of horizontal chases in
walls is prohibited. The conduits shall be fixed inside the chase
by means of clamps or by means of saddles not more than 60
cm apart.
Conduits shall be so arranged as to facilitate easy drawings of
wires through them. Entire conduit layout shall be done, in
such a way as to avoid additional junction boxes other than
light points. The wiring shall be done in a looping manner. All
the looping shall be done in either switch boxes or outlet boxes.
Looping in junction or pull boxes are strictly not allowed.
Where conduits cross building expansion joints.
Adequate
expansion fittings or other approved devices shall be used to
take care of any relative movement.
All conduits shall be installed so as to avoid steam and hot
water pipes. Conduits shall be installed in such a way that the
junction derivation and pull boxes shall always be accessible for
repairs and maintenance work. The location of junction / pull
boxes shall be marked on the shop drawings and approved by
the client. A separation of 200mm shall be maintained between
electrical conduits and hot water lines in the building.
Caution shall be exercises in using the PVC conduits in location
where ambient temperature is 50 0 C or above. Use of PVC
conduits in places where ambient temperature is more than 60 0
C is prohibited. The entire conduit system including boxes
shall be thoroughly cleaned after completion of installations and
before drawing of wires. Conduit system shall be erect and
straight as far as possible. Traps where water may accumulate
from condensation are to be avoided and if unavoidable,
suitable provision for draining the water shall be made.
All joining method shall be subject to the approval of the client.
Separate conduits shall be provided for the following system.
8.1.2.
-
15 A power outlet
-
5 A outlet and lighting system
-
Low Voltage system
-
Telephone / intercom system
-
Fire alarm system
-
C.C.T.V.system
-
Sound system
-
Computer data cabling system
-
Equipment wiring
CONDUIT JOINT :
Conduits shall be jointed by means of plain couplers. Where
there are long runs of strength conduit, inspection, type
couplers shall be provided at intervals, as approved by the
client. The conduits shall be thoroughly cleaned before making
the joints.
In case of plain coupler joints proper jointing
material like a vinylsolvent cement (gray in color) or any
material as recommended by the manufacturer shall be used.
8.1.3.
BENDS IN CONDUIT :
Where necessary bends or diversions may be achieved by
bending the conduits or by employing normal bends. No bends
shall have radius less than 2.5 times outside diameter of the
conduit. Heat may be used to soften the PVC conduit for
bending but while applying heat to the conduit shall be filled
with sand to avoid any damage to the cond uit.
8.1.4.
OUTLET :
All the outlet for fittings, switches etc., shall be boxes of
substantial construction. In order minimize condensation of
sweating inside the conduit, all outlet of conduit system shall
be properly drained and ventilated but in such a manner as to
prevent the entry of insects etc. Fixing between conduit and
boxes, outlet boxes switch boxes and the like must be provided
with entry spouts and smooth PVC bushes.
Joints between conduit and any type of boxes shall be effected
by means of conduits couplers into each of which shall coupled
smooth PVC bus from inside the box in any case all the joints
shall be fully water tight.
8.1.5.
BUNCHING OF CABLES :
Cables of A/C supply of different phase shall be bunched in
separate conduits. The number of insulted wires / cables that
may be drawn in to the conduits shall be as per the following
table. In this table the space factor does not exceed 40%.
However, in any case conduits having less than 19mm diameter
shall not be used.
Maximum permissible number of 650 volt grade single code
cables that may be pulled in to rigid pvc conduits.
CABLE SIZE IN 2mm
CABLE OF CONDUITS (mm)
(Max No. of cables)
19/20
25
32
38/40
51/50
1.5
4
8
15
-
-
2.5
4
6
10
-
-
4.0
2
4
8
12
-
6.0
1
-
6
8
-
10.0
1
-
5
10
-
16.0
-
2
4
5
12
Wires carrying current shall be so bunched in the conduit that
the outgoing and return wires are drawn into the same conduit.
Wires originating from two different phases shall not be run in
the same conduit.
8.2
WIRING SYSTEM RIGID STEEL PVC CONDUITS :
All conduits and its accessories shall be of threaded type and
under no circumstances pin grip type of clamp type accessories
be used.
8.2.1.
FIXING OF CONDUITS :
Conduit pipes shall be fixed by heavy gauge spacer saddles.
The saddles shall be of 3mm x 19mm galvanized mild steel flat,
properly treated with primer and painted securely fixed to
support by means of nuts and bolts / eye bolts, brass machine
screws, as mentioned at an internal of not more than one meter
but an either side of couplers, or bends or junction / pull /
outlet boxes or similar fittings saddles shall be fixed at a
distance of 30 cm from the center of such fittings.
Draw boxes shall be located at convenient location for drawing
of wires.
The conduit to be installed shall be of ample cross section area
to facilitate the drawing the wires. The diameter of the conduit
shall be elected as per table specified in this specifications. But
in no case it shall be less than 19mm diameter.
Entire conduit layout shall be done such as to avoid additional
junction boxes other than for outlet points. Conduits shall be
free form sharp edge and barriers. Conduit shall be laid in a
neat and organized manner as directed and approved by the
client. Conduit runs shall be planned so as not to conflict with
any other services pipe lines / duct.
All conduits shall be given two coats of self etching zinc
chromate’s primer before they are installed. Then after the
conduit shall be painted with two coats of enamel paints colour
as approved by the client.
The entire conduit system shall be electrically and mechanically
continuous and shall be bonded, together by means of approved
type earthing clamp and earthed through a bare copper
conductor of 14 SWG to the earthing terminals on the nearest
distribution board.
If requires, connection between PVC and steel conduits shall be
through a junction box. Direct connection between PVC and
panel conduits are not allowed. Where exposed conduits are
suspended form the structure they shall be clamped firmly and
rigidly to hangers of design to be approved by the client. Where
hangers are to be fastens into reinforced concrete appropriate
inserts and necessary devices for their fixing shall be left in
position at the time of concreting making holes and opening in
the concrete will generally not be allowed.
In case, it is
unavoidable prior permission of the client shall be abstained.
8.2.2.
CONDUIT JOINTS :
Conduit pipes shall be joined by means of screwed couplers and
screwed accessories as per IS : 2667. The threads shall be free
from grease or oil in long distanced straight runs of conduit,
inspection type couplers two way junction boxes at reasonable
intervals shall be provided or running threads with couplers
and lock nut shall be provided. The bare threaded portion shall
be treated with anti-corrosive paints. Threads on conduit pipes
in all cases shall be to full threaded portion shall have no sharp
edges not any burrs left, to avoid damage to the insulation of
conductors while pulling them through such pipes.
Brass female bushes shall be used in each conduit termination
in a switch box, outlet box, electrical panel or any other boxes.
Conduit shall be secured in each outlet box switch tight double
wire wound flexible steel conduit or any other approved method
shall be used. This shall be united to both sides with the rigid
conduits by suitable union.
Conduits installed in the plant room for mechanical equipment
all be properly clamped with the mechanical supports, but in no
case, it shall be fixed with the body of the equipment. The
connection of conduit to the mechanical equipment shall be
through oil tight double wire wound flexible steel conduit.
In any case the length of the flexible conduit shall not exceed
one meter. The flexible conduct shall be properly clamped with
the body of the equipment. They shall not in any case be
clamped with any cover of any removable parts of the
equipment.
8.2.3.
BENDS IN CONDUITS :
All necessary bends in the system including diversion shall be
done by bending pipes or by inserting suitable solid or circular
inspection type normal box or similar fittings. Conduit fittings
shall be avoided as far as possible on conduit system exposed to
weather, where necessary solid type fittings shall be used.
Radius of such bends in conduit pipes shall be not less than
75mm.
No length of conduit shall have more than the
equivalent of four quarter bends from outlet the bends at the
outlets not being counted.
8.2.4.
PROTECTION AGAINST DAMPNESS :
In order to minimize condensation or sweating inside the
conduit all outlet of conduit system shall be properly drained
and ventilated but in such a manner as to prevent the entry of
insects as far as possible.
8.2.5.
PROTECTION OF CONDUIT AGAINST RUST :
The outlet surface of the conduits including bends junction
boxes etc., forming part of the conduit system shall be
adequately protected against rust particularly when such
system is exposed to weather. In all cases no bare / threaded
portion of conduit pipe shall be allowed unless such bare
threaded portion is treated with anti-corrosive coating or
covered with approved plastic compound.
All screwed and
socketed connection shall be adequately made fully water tight
by the use of proper jointing material i.e., while lead for metal
conduits.
8.2.6.
BUNCHING OF CABLES :
Unless otherwise specified insulated conductor of different
phase shall be bunched in separate conduit. Wires carrying
current shall be so bunched in the conduit that the outgoing
and return wires are drawn in to the same conduit. wires
originating from two different phase shall not be run in the
same conduit. The number of insulated wires/cables that be
drawn into the conduits shall be as per the following table:
Maximum permissible number of 650 volt grade single code
cables that may be pulled in to rigid pvc conduits.
CABLE
SIZE 2 (in mm)
SIZE OF CONDUITS (mm)
20
25
32
38
51
MAXIMUM No. OF CABLES
1.5
5
10
14
-
-
2.5
5
8
12
-
-
4.0
3
6
10
-
-
6.0
2
5
8
-
-
10.0
-
4
7
6
-
10.0
-
3
5
6
-
8.3
25.0
-
-
3
4
6
35.0
-
-
2
3
5
50.0
-
-
-
-
4
SWITCH AND SOCKET
Switches shall be installed at 900mm above finished floor level
unless otherwise indicated on the drawings.
The switch controlling the light point or fan shall be connected
on to the phase wire of the circuit and neutral shall be
continuous having no fuse or switch installed in the line except
at the DB. All fan regulators shall be fixed inside the switch
boxes on adjustable flat MS strips / plates with tapped holes
and brass machine screws, leaving ample space at the back and
sides for accommodating wires.
The cover plates to the switch box shall be fixed by means of
sunk head brass cadmium screws.
Where two or more switches and fan regulators are installed
together, they shall be provided with one gang cover plate with
knockouts to accommodate required number of switches
sockets and regulators.
The switch controlling the socket outlet shall be on the phase
wire of the circuit.
The third pin of the socket shall be
connected to the earth continuity conductor of the circuit. The
switch boxes installed back in the same wall shall be offset from
each other 15mm horizontally to preclude noise transmission.
9.0
DRAWING OF CONDUCTORS :
Air through the conduits : The drawing and jointing of copper
conductor of wires shall be executed with due regard to the
following precautions. While drawing insulated wires into the
conduits, care shall be taken to avoid scratches and kinds
which may cause breakage of conductors. There shall be no
sharp bends.
Insulation shall be shaved off for a length off 15mm at the end
of wire like sharpening of a pencil and it shall not be removed
by cutting it square edge.
PVC insulated copper conductor core ends before connection
shall be properly soldered (at least 15mm length) with soldering
flux / copper solder for connecting to the terminals. All strands
of wires shall be soldered at the end before connection. The
looped joints shall be just adequate, neither too much not too
less. Conductors having nominal cross section area exceeding
4 Sq.mm shall always be provided with crimping type cable
socket. At all bolted terminals, brass flat washer of large area
and approved steel spring washers shall be used. Brass nuts
and bolts shall be used for all connections.
Only certified wire man and cable jointers shall be employed to
do joining work. For all internal wiring PVC insulated wires of
650/100 V grade shall be used. The sub circuit wiring for point
shall be carried out in looping system and no joint shall be
drawn in any conduit, until all work of any nature that may
cause injury to wire is completed. Care shall be taken in
pulling the wires. Before the wires are down into the conduits
the conduits shall be thoroughly cleaned of moisture, dust and
dirt or any other obstruction by forcing compressed.
10.0
JOINTS :
The wiring shall be looping back system and hence all joints
shall be made at main switches distribution boxes only. No
joints shall be made inside conduits and junction boxes.
Conductors shall be continuous form outlet to outlet. Joints
where unavoidable, due to any specified reasons, prior
permission in writing shall be obtained from the client before
making such connections. Joints by testing conductors are
prohibited.
11.0
LOAD BALANCING :
Balancing of circuits in three phase installation shall be
planned before the commencement of wiring and shall be
strictly adhered to.
12.0
EARTHING :
All earthing system shall be in accordance with IS : 3043, 1985
code of practice for earthing. The type and size of earthing wire
shall be as specified in clauses under the heading of cables.
13.0
TESTING OF INSTALLATION :
Before a completed installation is put into service the following
tests shall be complied with:
13.1.
INSULATION RESISTANCE :
The insulation resistance shall be measured by applying 500 V
megger with all fuses in places, circuit breaker and all switches
closed.
The insulation resistance in megohms of an
installation, measured shall not be less than 50 megohms
divided by the number of points on the circuit.
The installation resistance shall be measured between
EARTH TO PHASE
EARTH TO NEUTRAL
PHASE TO NEUTRAL
13.2.
EARTH CONTINUITY PATH :
The earth continuity conductors shall be tested for electrical
continuity and the electrical resistance of the same along with
the earthing lead but excluding any added resistance of earth
leakage circuit breaker measured from the connection with the
earth electrode to any point in the earth continuity conductor in
the completed installation and shall not exceed one ohms.
13.3.
POLARITY OF SINGLE POLE SWITCHES :
A test shall be made to verify that every no linked single pole
switch is connected to one of the phase of the supply system.
13.4.
COMPLECTION CERTIFICATES
All the above tests shall be carried out in presence of client and
the results shall be recorded in a prescribed forms. Any default
during the testing shall be immediately rectified and that
section of the installation shall be retested. The completed test
result forms shall be submitted to the client for approval.
On completion of an electric installation a certificate shall be
furnished by the contractor countersigned by the certified
supervisor under whose direct supervision the installation was
carried out. This certificate electric supply authority.
EXTRA LOW VOLTAGE SYSTEM TELEPHONE / COMPUTER
WIRING
INSTALLATION :
1.0
SCOPE :
1.1
This section related to specification for the supply installation
connection testing and commissioning of the telephone /
computer wiring installation including supply of telephone
cables, co-axial wire, multiple flexible wire, shielded wire,
Ethernet computer signal wire junction boxes outlet boxes rigid
PVC conduit and conduit.
Accessories and other related
accessories require to complete the conducting, wiring and
installation.
1.2
The Main Hardware of the systems shall be supplied by the
client.
2.0
SYSTEM :
2.1
Telephone System
Voltage
Frequency
90 V Ac -
300 Hz – 5 Khz
2.2
A multi pair telephone cable will be provided by the “Telephone
Department” at a location as shown in the drawing.
2.3
The extra low voltage system cable will be terminated on the tag
block / junction box located as shown on the drawing.
2.4
From this tag block / junction boxes separate rigid PVC
conduits shall run for individual outlet connection to each area
through tag boxes junction boxes.
2.5
The conduits shall run in the surface/concealed manner in the
vertical shaft and shall run in concealed conduits system at
every floor between the extra low voltage shaft and the outlet
box through tag box/junction boxes located on the floor.
2.6
Extra low voltage system cables / multi pair telephone cables
shall be pulled through the above conduits and then be
connected at both ends.
3.0
MATERIAL OF CONSTRUCTION :
CONDUIT :
Rigid PVC conduit, conduit accessories steel junction boxes
etc., to be used telephone wiring system shall have material
specifications at described in section under title : INTERNAL
WIRING of this tender document.
3.1
CABLES AND WIRES :
The type of cables and the services shall be as follows :
Indoor/outdoor Multi pair PVC insulated sheathed armoured
and sheathed for Telephone system.
Inside twin core PVC insulated with twisted core with conduit
for telephone.
Ethernet computer signal cable to be used for computer wiring
in conduit.
3.2
Telephone wires / cables shall be twin / multi pair PVC
insulated and sheathed wires with Tinned Copper conductor
not less than 0.6mm dia and shall be colour coded twisted pair
with rip cord.
Cables laid under ground or locations subject to dampness and
flooding hall be filled with polyethylene compound and shall
have sufficient protection against moisture and water ingress.
All armoring shall be of galvanized steel wires and protected
against corrosion by an outer sheath of PVC in the case of
indoor cables and polyethylene in the case of out door cables
outer sheathing must be fire retarding and anti-termite.
All unarmored single/twin core cables and inner sheath or
armoured cables shall be provided with ripcord.
All single / with pair cables for final extension to the telephone
outlet box shall be unarmoured tinned copper conductors of not
less than 0.6 mm dia and shall be drawn in conduits.
3.3
TELEPHONE SOCKETS :
The telephone socket outlet shall be heavy flush mounting type
and be 2A 2 pair polythene connector in steel box or of the
make as approved by the consultants. In no circumstances the
extra low voltage system socket outlets and electric power
socket outlets shall be interchangeable with each other.
3.5. JUNCTION BOXES FOR EXTRA LOW VOLTAGE SYSTEM :
The junction boxes / the telephone tag blocks shall be suitable
for the multi pair telephone cables and shall have two terminal
blocks, cross connect type. All incoming and outgoing cables
shall be terminated on separate terminal blocks and
terminations shall be silver soldered. The cross connection
jumpers shall be insulated wires of same diameter and screw
connected.
The junction boxes shall be mounted inside fabricated 14 gauge
sheet steel boxes with removable hinged covers and shall be
painted with 2 coats of red oxide and stove enameled.
4.0
INSTALLATION :
4.1
The extra low voltage system wiring installation shall be carried
out in the manner as approved by the Local Authority. If found
necessary the drawing for installation shall be got approved by
the local sanctioning authorities before commencement of the
work.
4.2
Separate conduits of 25mm shall be carried out as per detail
specification given under section “INTERNAL WIRING”.
4.3
All cables shall be laid on cable racks / trays and neatly
stitches together.
4.4
Extra low voltage system wires / cables termination’s both at
the junction boxes and at the socket outlets shall be done as
per method approved by consultants and in conformity with
their rules and regulations. The connection at the junction
boxes shall be silver soldered so as to achieve minimum contact
resistance.
4.5
The final branch connections with single / twing pair cables in
conduits and the minimum number of cables in each conduit
shall be as follows:
Conduit dia inch/mm
Max. No. of cables
¾
(20)
2
Nos. Single pair
1
(25)
6
Nos. Single pair
1¼
(32)
12
Nos. Single pair
1½
(40)
18
Nos. Single pair
5.0
METHOD OF MEASUREMENT :
5.1
The extra low voltage system cable shall include supply, laying,
connection, testing and commissioning of multi pair cable on
ceiling / wall on cable trays / racks including all supports and
shall be measured and paid on running length basis. Cable
trays/racks shall be paid for separately.
5.2
The multi pair junction boxes for extra low voltage system shall
conduits of strips jumpered interconnections silver soldered,
enclosure etc., and shall be measured and paid as one unit.
5.3
The conduit wiring for extra low voltage system outer point shall
include wire/cable in rigid PVC conduits and shall include
junction boxes pull boxes, 2A two pair connector/socket in GI
box formica cover etc., from the floor tag blocks to the outlet
point.
LIGHTING DISTRIBUTION BOARD :
1.1
SCOPE :
This section relates to specifications for supply assembly
installation connection, testing and commissioning of lighting
distribution board (LDB) using TPN/FD/DD/SP MCB MCB
Isolator & MLCB, Earthing terminal CRCA sheet housing and
complete the item, installation.
1.2
SYSTEM :
This lighting distribution boards shall be suitable for operation
on 440/220 V, 3/1 phase, 4/2 wire, 50 cycle per second A.C.
Supply system.
The lighting distribution boards shall be
capable of with standings short circuit current of 9 KA.
1.3
CONSTRUCTION :
1.3.1.
The DB’s shall be factory made and of those and as per the
C.A. layout enclosed. In no circumstances the fabricated
board of any Associate of ‘sister’ concern of those equivalent
of any local manufacturer shall be utilized.
General
arrangement layout of the DB’s shall be approved by the
consultants in charges before manufacturer.
1.3.2.
The DB shall metal clad duly fabricated from 2mm thick
high quality CRCA sheet metal.
1.3.3.
The DB shall be wall mounted and dead front operated.
1.3.4.
The DB shall totally be enclosed and made dust vermin and
weather proof such that it meets to IP 54 protection
classification.
1.3.5.
A detachable cover plate of 2mm thick CRCA sheet to the
provided front of the board such that al love parts of the
electrical accessories mounted on the board can be
accessible only on removal of the said cover plate.
The cover plate shall be fixed to the board with adequate
size zinc passivated of machine screws.
Above the detachable cover plate one additional hinged door
of 2mm thick CRCA sheet shall be provided with a suitable
locking arrangement.
The hinged door shall be provided with a suitable gasket
capable of with standing corrosive and humid atmosphere
and to maintain degree of enclose reprotection IP 54 as per
IS.
1.3.6.
The DB shall have top/bottom entry arrangement or
incoming and outgoing cable/conduits.
1.3.7.
All hardware to be used in manufacture of the DB shall
either be of mild steel zinc passivated or otherwise be
treated to prevent corrosion due to humid atmosphere
prevailing at the project site.
1.3.8.
All internal electric connection shall be carried out using
660/1000 V grade PVC insulated copper conductor of ISI
approved make, laying rated current carrying capacity to
carry continuous full current of respective switch fuse
rating at operation conditions prevailing at the project site.
1.3.9.
The DB internal shall be earthed with use or copper
wires/strips running through out the length size of the
earthing strip/wire shall be as shown in the respective
drawing.
1.3.10.
All non current carrying metal surface of the DB’s shall
adequately be treated with seven tank pretreatment process
to render it free from grease, oil oxide etc., to make them
ready to receive and hold coats of zinc chromate’s primer.
1.3.11.
The surface imperfection shall then be rectified with
applications of putty and then rectified portion of the
surface shall be covered with thought primer and be
finished by spraying two coats or stove Enamel paint to
approved shade.
1.3.12.
The finished painted surface then shall be dried in stoving
oven in dust free atmosphere.
1.3.13.
The DB’s shall be provided with electric components and
accessories as per the details shown in the drawing for the
respective electric distribution board.
1.4.1.
The DB’s shall be inspected and checked as per inspection
manual of the DB manufacturer.
1.4.2.
Various electrical components and accessories of the board
shall be checked as per drawing for the respective DB’s.
1.4.3.
The DB’s shall be checked for rigid mounting, earthing
connection, proper rating and size of components internal
wiring etc.
1.4.4.
All mechanical fasteners and electrical connections shall be
checked and tightened before installation.
1.5
INSTALLATION :
1.5.1.
The DB’s shall be assembled and aligned together and be
installed at site per installation manual/instruction of the
DB manufacturer.
The installation shall confirm to relevant Indian Standard
specification and requirement of local site conditions.
1.5.2.
The DB shall be installed in surface manner at the location
as shown in the respective drawings.
1.5.3.
All minor electrical and mechanical work required to be
attended to on the DB shall be completed in an approved
manner after installation but before energizing the DB’s.
1.6
TEST
Prior to commissioning of the DB’s following tests shall be
carried out :
1.6.1.
Mechanical endurance test shall be carried out by closing
and opening of al the MCB's switches etc.
1.6.2.
Insulation resistance test shall be carried out between
phases and between phase to earth bus, keeping the
insulating switch in open position. Similar test shall be
carried out keeping the isolating switch in closed position.
1.6.3.
All the interlocks, controls and tripping mechanism or the
switch gears shall be tested for their proper functioning.