Page 509 - IRSEM_Main Book

Section 3: Installation of Relay Interlocking

21.3.1 Wiring and Relay Racks

(a) The wiring used in various equipment shall comply with the requirements
laid down in IRS specification No. S 23.
(b) All wiring in the cabin and locations shall be 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.
(c) All wiring in the cabin and location shall be terminated on approved type
terminal blocks/tag blocks unless otherwise specially permitted.

(d) At all locations and cabins, cable/entry arrangements of adequate size,
conveniently located for ease of approach to terminals and other
equipment so arranged as to protect the wires from damage, shall be
provided. Such cable/entry arrangements shall be plugged and sealed with
suitable compound after the wiring is completed.

(e) The internal wiring of relay rack in locations and cabin shall be generally
carried out with plain annealed copper conductors; PVC insulated
unarmoured flame retarding type of 1100V grade unless otherwise
specially permitted. The size of the conductors may be as follows:

Type Size

(a) Single Core size 1 mm

(b) Multi core each core of size 1 mm

(c) Multi core each core of size 0.6 mm

(d) Flexible insulated wire size 16/0.20 mm

(e) Flexible multi strand wire size 3/0.75 mm

(f) Rack to rack wiring shall be generally carried out with multi core cable
having plain annealed copper single core conductor of size 1/0.6 mm or
multi-strand 16/0.2 mm as per approved specification for indoor cables.

(g) Following practice shall be adopted for internal wiring. The connecting
wires shall be terminated on eyelets/lugs/receptacles unless otherwise
specially permitted.

(i) All connections to plug-in non-proved type relays flexible wire of
16/0.20 mm shall be used.

(ii) All connections to proved typed relays shall be done with 0.6/1 mm
single strand multi core cable.

(iii) For all connections from cable terminations to tag blocks and indicators etc.
shall be done with the help of 1 mm single strand wires.

(iv) For all connections to circuit breakers, lever locks etc. single strand
wire of 1.5/1.6 sq. mm size shall be used.

Chapter 21: Relay & Electronic Interlocking Page 452 of 535