FTN design & development specification (D&D)

SP FTN (D&D) 003

Screening Conductors for Immunisation of Telecommunications Cables

Issue 2, April 2003 · FTN D&D specs & typical drawings

Product specification for the single-core PVC-insulated aluminium screening conductor used to immunise telecoms cables in ac electrified areas. Designers use it for the two conductor sizes, sheath marking, factory tests, drumming and Product Acceptance.

Clause map — what each clause deals with

1	References	British Standards the spec relies on.
1.1	British Standards	Lists the BS documents for stranded aluminium conductors, terminology, PVC covering and spark testing.
2	General	Scope and definitions.
2.1	Scope	Applies to single-core stranded aluminium conductor with PVC insulation used for screening telecoms cables.
2.2	Definitions	Cable definitions taken from the BS glossary.
3	Construction	How the conductor and its sheath are built and marked.
3.1	Conductor	Conductor stranding standard.
3.2	PVC Sheath	Sheath material type and colour.
3.3	Conductor Cross Sectional Area	The two available conductor sizes and their strand make-up.
3.4	Sheath Marking	What the oversheath legend must say, repeat interval and length marking.
4	Testing	Factory acceptance tests on the finished conductor.
4.1	Measurement of Thickness of Insulation	Minimum radial insulation thickness and test method.
4.2	Insulation Resistance Test	Minimum insulation resistance per km and test method.
4.3	Spark Test	Spark test voltages for the PVC covering.
4.4	Resistance	Maximum dc conductor resistance; Table 1 summarises dimensions, sheath and resistance for both sizes.
5	Miscellaneous	End sealing and drum requirements.
5.1	Sealing and Marking of Ends	Ends capped after test to keep moisture out.
5.2	Drumming	Drum size, standard length, spindle hole sizes, labels on drum and cable with required contents, rolling arrow, battening.
6	Product Acceptance	Manufacturer must hold Network Rail Product Acceptance; tests required and notice of design changes.