Standards

• Telcordia (Bellcore) GR-421

Construction

Conductors
Solid annealed bare copper, 0.4/0.5/0.63/0.9mm, as per ASTM B-3/class 1 of IEC 60228

Insulation
Solid medium or high density polyethylene as per ASTM D 1248/IEC 60708

Twisted Pairs
Insulated conductors are twisted into pairs with varying lay length to minimize crosstalk

Cabling Element
Twisted Pairs

Cable Core Assembly
Cables with up to 400 pairs are composed of 25-pair units or 12/13-pair units; cables with over 400 pairs are composed of 50 or 100-pair units. Any extra pairs form a separate unit. Units are identified by colour coded binders. Construction is per GR-421 given in Cable Make Up Diagram.

Core Wrapping
One or more non-hygroscopic polyester tapes are helically or longitudinally laid with an overlap. These tapes furnish thermal, mechanical as well as high dielectric protection between shielding and individual conductors

Moisture Barrier
A layer of bare aluminium tape (0.2mm/8mil) is applied longitudinally with overlap over the cable core to provide 100% electrical shielding coverage and ensures a barrier against water vapor. In cables with more than 200 pairs, the aluminum tape may be corrugated for improved cable flexibility

Sheath
Black low density polyethylene as per ASTM D 1248/IEC 60708, being able to withstand exposure to sunlight,
temperature variations, ground chemicals and other environmental contaminants

Ripcord
Ripcord may be provided for slitting the sheath longitudinally to facilitate its removal

Spare Pairs (optional)
Spare pairs may be incorporated for large pair cables

Continuity Wire (optional)
One tinned copper drain wire may be longitudinally laid to ensure electrical continuity of the screen

Optional Construction

Armoured Cable
0.15mm thick corrugated steel tape armour is applied with an overlap over an optional inner polye-thylene sheath. An outer polyethylene sheath is applied over the armour

Self-Support Cables
A 7-strand galvanized steel strand is used as support wire. Black polyethylene sheath covers both
core and support wire in a figure-8 construction

Aabbreviations

LAP (CAP):Copolymer coated aluminium tape + PE sheath
LAPSP (CAPSP):LAP sheath + steel tape armour + PE sheath
AP (ALPETH): Bare aluminium tape + PE sheath
PAP: PE inner sheath + bare aluminium tape + PE sheath
PASP: PE inner sheath + bare aluminium tape + steel tape armour + PE outer sheath
ASP (STAPETH): Bare aluminium tape + steel tape armour + PE outer sheath
CACSP: Copolymer coated aluminum tape + copolymer coated steel tape armour + PE outer sheath
LAPSP: Copolymer coated aluminum tape +PE inner sheath + steel tape armour + PE outer sheath
FIGURE 8 LAP: Copolymer coated aluminum tape + PE outer sheath + self supporting

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