Railway Signalling Flexible Screened Multi core cable Cable Routes

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Railway Signalling Flexible Screened Multi-core cable Cable Routes

Production/ Batch tests 

The following test will be performed on every manufactured batch of cable.

Spark test:

• The test procedure shall be as defined in LU specification E4156. The test shall be performed on the conductor and screen insulation during manufacturer.

• Voltage withstand and insulation resistance test on complete cable(tested dry). The conditioning, test procedure and results supported shall be as defined in LU specification E4156. The test shall be performed on the entire manufactured length of cable. No insulation breakdown shall occur. The insulation resistance shall be atleast 350 mega ohms per kilometer.

Production/ Batch tests:

• Voltage and insulation resistance test on cable components (tested wet). The conditioning, test procedure and results supported shall be as defined in LU specification E4156. No insulation breakdown shall occur. The insulation resistance shall be atleast 350 mega ohms per kilometer.

Conductor resistance test:

• The test procedure shall be defined in LU specification E4156. The test shall be performed on the entire manufactured length of cable. The conductor resistance shall be in accordance with the manufacturer’s design.

Life expectancy:

• The cables once installed shall remain in constant service for an expected 40 years as per LUL specification E4156.

Cables Availability:

Vital concentric signalling cables
• 1 pair
• 3 pair and
• 7 pair

Shielded multicore cables 1.0 mm²
• 2 core
• 4 core
• 6 core
• 7 core
• 12 core
• 16 core and
• 27 core

Cables Availability:

Shielded Multi core cables 1.85 mm²
• 2 core
• 4 core
• 6 core
• 8 core
• 10 core
• 16 core
• 19 core
• 27 core and
• 37 core

Cables Availability

Flexible Screened Multi core cable
• 2 core
• 4 core
• 6 core
• 7 core
• 10 core and
• 12 core
Track connection cable
• 1 core
Track crossing cable
• 5 core
• 10 core

Cable Routes:

• Vital signalling cables shall be kept separate from power cables and, where possible, from control systems and communications cables, e.g. by running in separate shelves of a cable run. (Cat 2)

• The route shall have the capacity to hold all the required cables, together with a 20% spare capacity to cover future needs.(Cat 2)

Design Consideration:

• All track side signalling equipment shall be connected locally to the main track side signalling cables via track side disconnection boxes to facilitate ease of installation, maintenance testing and fault finding.

• All equipment requiring greater than a two wire (plus earth) connection shall be connected via a keyed plug and socket (or equivalent) system which is constructed to a grade of appropriate integrity.

Other Consideration:

a) All cable types shall be identifiable by examination of the sheaths.
b) Cable routes shall be designed to suit the mechanical characteristics of the cable and the installation techniques to be employed. When utilising exiting cable routes, the mechanical characteristics and installation techniques shall be selected accordingly.

c) Where cable routes cross the track they shall be in either overhead runs or in purpose designed cable ducts which fully protect them and do not require the cables to be disturbed during track renewal.

d) With the exception of main power supply cables, all cables entering and leaving signalling equipment rooms, signal apparatus boxes and wayside kiosks shall be terminated on separate cable racks in order of their core numbers on a combined terminal or disconnection, or terminal or fuse links. Each wire shall be capable of being individually disconnected and isolated without removing the wire itself. These links shall be easily accessible for test purposes. Each link or terminal shall be identified and labelled. Power supply cables shall be terminated by a means appropriate to their size and current capacity.

Internal Wiring:

1. All wires shall be terminated.
2. Every end of a wire shall be labelled at the ends of its termination points. The label shall be of a form which cannot be removed without disconnecting the wire.

3. Wire racking shall be earthed and provision made, where practicable, for the isolation of individual racks for fault finding.
4. No joints or splices of any type shall be permitted in wires between terminations.
5. Redundant wiring shall be removed. In the event that a concession is granted to allow the non removal of a wire, then that wire shall be so identified with a label.

Where it is not practicable to physically remove disconnected wiring, the ends shall be cut back ,capped and secured

Internal Wiring


Circuit requirement

1. Circuits leaving or entering the SER shall be protected by links or isolators. These links or isolators shall be of a type capable of being secured in the isolated condition.

2. Where there is significant risk that the circuits may come into contact with 600V traction rails (e.g. track circuits rail connections) then the links or isolators shall be replaced by fuses or suitable protective devices. Links, isolators, fuses or MCB’s used at the entry point of SER’s on new installations shall provide touch protection against electric shock.

3. They shall also incorporate touch protected connection points on both sides of the isolation to permit a remote switch to be wired across the isolator for simulation purposes during testing, and for the application of test instruments during fault finding. These connection points shall permit the rapid disconnection of the simulation facilities without disturbance to the permanent wiring. The exact form of connection shall be agreed with the Trains System Engineer.

4. A maximum of two wires shall be connected to any one terminal except on diagrams where terminals are provided for multiple connections.
5. A minimum of 10% spare terminals shall be provided on each terminal block on the rack. Terminals used to terminate spare multi core wires shall not be considered as spare terminals.

6. There shall be only one feed per circuit.
7. Where plug connections are used, the wiring shall be arranged such that no voltage is present on exposed pins when disconnected. The plug connectors used shall be mechanically keyed to prevent improper insertion and identify equipment of compatible types.

8. Cable cores, whether main cables, tail, or multi cores shall be terminated. It is not permitted to cut back spare cores in SER’s containing safety wiring.

Production Validation:

1. No cables or wire shall be supplied unless a formal ‘Authorised to supply product’ letter covering the specific cable or wire concerned has been issued by LUL’s Standards Engineer or the materials engineer of an Infraco.

2. Grandfather rights shall not be an acceptable alternative to an ‘Authority to supply product letter’ issued as a result of successful product validation to current standards.

3. For cables or wires that are not already covered by an ‘Authorised to supply product’ letter reference should be made to E4156 for the testing and documentation that must be submitted by the supplier to Thales.
4. Copper conductor resistances should be in compliance with BS6360. The referenced typical PICO values are a guidance for installers only.


1. The details of the type tests required are specified in E4156 (Appendix B & C).

2. The requirements of 2-01001-002 for fire performance supersede the smoke emission, toxicity and flammability requirements of E4156 or those found in any of the particular cable specifications referenced.

3. Suppliers attention is drawn to the relevant clauses in E4156 concerning the restrictions on acceptable testing facilities.

Fire Performance Requirements

1. The fire performance requirements for cables on London Underground infrastructure are extremely stringent, refer to LUL Standard 2-01001-002 A1, Fire Safety performance of materials.

2. The Supplier will be required to conduct type tests, in accordance with E4156 and 2-01001-002, Fire Performance, in particular covering the three main areas of Flammability, Smoke Emission and Toxicity.

3. The Jubilee and Northern Lies are predominantly tube section and therefore LS0H sheaths and non-PVC insulation will be a standard requirement of most cables.


Production/ Batch tests, Spark test, Conductor resistance test,Life expectancy,Cables Availability, Flexible Screened Multi core cable, Cable Routes,Design Consideration,Internal Wiring, Circuit requirement,Fire Performance Requirements

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