This document provides a checklist for wiring inspections of signaling and telecommunications systems. It outlines procedures to check that indoor and outdoor wiring is neat, properly labeled and protected. Key points include verifying correct cable types and sizes are used for different applications, terminals are clearly marked, connections are properly soldered and bundled, earthings meet resistance requirements, and tools are available for maintenance. The checklist aims to ensure work is done safely and to a high quality standard.

1. CHECK LIST FOR S & T INDOOR & OUTDOOR WIRING-REV-00
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1. General Check
Þ Check all wiring used in the Cabin and Locations are done in a neat manner so that the
wiring does not in any way prevent the proper functioning over working parts and is easily
accessible for maintenance
Þ Check at all locations and cabins wire entrance of adequate size, conveniently located for
ease of approach to terminals and other equipment so arranged as to protect the wires
from mechanical injury and wire entrance are plugged and sealed with suitable compound
after the wiring is completed
Þ Check Relay to Relay wiring on the same rack is as far as possible be direct without
intermediaries like tag blocks/terminals
Þ Check Identification Marker for Identifying the terminals and tags are provided at each
terminal to identify the circuits for which it is used
Þ Check Relay racks have sufficient capacity to take additional equipment to the extent of
15% of equipment provided to permit additions and alterations.
Þ Verify Charts showing the positions of relays on relay racks and contact arrangement of
relays indicating the spare and used contacts are prepared and kept in the cabin.
2.Indoor Signaling Cable
Indoor Signaling Cable is used for indoor wiring of signaling circuits.
Check following cables are normally being used for indoor signaling applications:
Ø 16/0.2 mm Wiring of Q series and Shelf type Relays
Ø 3/0.75 mm Wiring of shelf type Relays
Ø 1/1.4 mm Wiring of lever lock, Circuit Controller
Ø 7/1.4 mm Power supply – Battery room to Charger and Busbar
Ø 1/ 2.5 mm Wiring of Bootleg ( track Circuit)
Ø 40/0.6 &60/0.6 mm Rack to Rack wiring in metal to metal type Relays
Ø 24/1.0,40/1.0 & 60/1.0 mm Wiring of Control / Relay rack up to Cable termination
Rack for outdoor Circuit ( signal and Point)
Ø 1/0.6 mm Wiring of Tag block to Wiring of Tag block ( except signal and point)
Ø 1/1.0 mm Wiring of Tag block to Tag block ( Signal and Point)
Ø 36/0.3 mm Wiring of Track relays from MDF
Verify Busbar conductors are so chosen that voltage drop is not more than 0.5% of
busbar voltage between battery terminals & busbar in equipment room.
3. Marking and Labelling
Ø Check Conductor marking and labelling aredone by means of plasticferrules with embossed
letters. Alternatively, a chain of pre-embossed plastic ferrules used.
Ø Check Terminal numbers should be properly marked.

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4.Bunching & Lacing
ü Check All the inter-relay wirings and inter rack wiring are neatly bunched in a circular
shape
ü Check Black twine or plastic strip of suitable design are used for lacing of thewires.
5.Soldering Connections
Ø Verify Staff working in the installation and maintenance of S&T equipment are conversant
in use of soldering iron/gun for making good soldering joints.
Ø Ensure care is exercised to avoid dropping of solder particles and wire clipping on adjacent
terminals and apparatus.
Ø Ensure soldering irons of adequate wattage for the type of work done and the following
are on hand:
§ A small file for dressing the soldering tip.
§ A fire-proof pad for wiping the tip.
§ A mica sheet of adequate size or a suitable stand for soldering iron.
§ Electrical soldering irons is switched off when not in use over extended period.
Ø Verify while making a soldering joint, the surface thoroughly cleaned, fluxed andtinned.
Ø Ensure use of too much solder is avoided to prevent lumpy connections.
Ø Ensure soldering iron is not be held on the wire connection for too long to avoid damage to
insulation.
Ø Ensure Imperfect joints are the result of any one of the following causes, which should be
avoided:
• Soldering iron not sufficiently hot.
• Soldering iron held on the connection for sufficient time.
• Unclean terminal or wire
• A solder of improper composition or inferior fluxing agent.
• A newly soldered connection is not be disturbed till the solder has thoroughlycooled.
6.Wire Termination
Ø Ensure while terminating wires, care is taken to bend the wire in clock wisedirection.
Ø Ensure wire strippers used for the purpose of stripping off the wire insulation. Cutting-pliers
are not be used for this purpose.
Ø Check washers and check nuts are used whilst fastening.
Ø Ensure not more than two wires are terminated on one terminal
Ø Ensure multi-strand wires are terminated on terminal lugs and covered with insulation
sleeves.
Ø Ensure wires of cable are neatly terminated and properly bunched.
Ø Ensure connections from and between Secondary cells
Ø Check inter connections between secondary cells, standard lead strips, supplied by the
manufacturer is used.

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Ø Verify flexible multi-strand copper cable PVC insulated single core of nominal Cross
Sectional area 10 Sq.mm. (7/1.4 mm.) is used for wiring between secondary cells to battery
chargers/terminal board. The ends are crimped with a copper ring conductor (eyelet) and
then terminated. However, the voltage drop between battery terminal and bus bar does
not exceed 0.5 V under full load condition.
7.The following colour code of wires are used:
Ensure
Ø Between Battery charger and Red for positive Batteries/ Terminal Board
& Black for negative
Ø Earth connections Grey
Ø AC side wiring - Blue for neutral and Yellow for phase.
8.Earth connections
v Ensure separate earth are provided for each block instrument at a station.
v Check the resistance of earth for signaling circuits does not exceed 10 ohms. If it is not
possible to reduce the earth resistance below 10 ohms additional earth may be provided in
parallel.
v Check Where more than one earth is used, the distance between earthing pipes is not less
than 3 metre. Conductor leading to these earthing is electrically insulated from each other
throughout and also from metallic structures connected to different earths.
9.Earthing Leads
Ø Check earth wires are protected against mechanical damage and possibility of corrosion
particularly at the point of connection of earth electrode.
Ø Verify the earthing lead is of mild steel flat of size 35mm x 6 mm. or copper wire of 29 sq.mm
cross-sectional area (19 strands of 1.4 mm dia). In case the conductor is buried
underground, it is protected from corrosion by an application of suitable anticorrosive paint
o bitumen or varnish. The length of the cable so treated is extend half a metre beyond the
buried length.
Ø Check the earthing lead is soldered or crimped on a lug which should be bolted to the earth
electrode.
10.Conventional Earthing
ü Verify In this type of arrangement, the earthing is achieved with the help of Earth
electrode (normally GI pipe) buried in the ground (earth pit).
ü Check the earth electrode is surrounded by filling material (Common salt and
Charcoal) and it is connected to the equipment with the help of GI or copper wire to
extend earth to the equipment.
ü Verify this type of earthing is normally provided for apparatus cases, signaling cables,
block instruments, conventional power supply equipment etc.

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11.Earthing & Surge protection for S&T installation
Effective or Maintenance-free earthing
Ø Check this type of earthing is provided with earth electrode of a highly conductive,
corrosion-resistant material with low soil resistivity earth enhancement compound
around it.
Ø Verify this arrangement eliminates the drawbacks of conventional earthing such as
corrosion of electrode and high and fluctuating earth resistance.
Ø Check maintenance free earthing is provided for signaling and telecom equipment
with solid state components requiring low earth resistance of the order of 1 Ohm such
as Integrated Power Supply, Digital Axle Counter, Data Logger, Electronic Interlocking
etc.
12.Check Measured Earth resistance value is not more the specified value below
1. Telegraph and Block Instrument using earth return circuit 10 Ω
2. Earths for surge arrestors/ lightening dischargers 10 Ω
3. Earthing of Signaling equipment 10 Ω
4. Earthing of signaling cable screen in AC electrified areas 10 Ω
5. Earthing of Telephone Exchange 5 Ω
6. Earthing of aluminum sheathed telecom cable in AC electrified area 1Ω
7. Earthing of equipment in VF repeater stations and cable huts 5 Ω
8. Axle counter cable screened in AC electrified area 1 Ω
9. Electronic Interlocking installation 1 Ω
10. Integrated Power Supply System & its individual modules 2 Ω
11. Digital Axle Counter EJB and its apparatus case connected to same earth All cable
armours connected to same earth 1 Ω
12. Reset box of Digital Axle Counter connected to earth (indoor) near SM Room 1Ω
13. Tools for Wiring
Ø Stripper and cutter suitable for wires 0.6 sq.mm to 1.5 sq.mm. and 2.5sq.mm.
Ø Crimping tool.
Ø Soldering iron or Soldering Gun of suitable wattage.
Ø Socket set consisting of 19 sockets and other accessories for maintenance of point
machine.
Ø Socket driver tester set.
Ø Screw driver set
Safety and Quality First
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