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Ordering Information

 Solid PE Insulated & LAP Sheathed (ALPETH) Air Core Cables to GR-421

Application

The cables are designed for use as subscriber distribution cables and as connection between central offices. The

cables are suitable for installation in ducts, direct burial in the ground and also for aerial installation with integral

suspension strand. An armoured option is offered for direct burial installations. A figure-8 self support option is

offered for aerial installation.

Standards

Telcordia (Bellcore) GR-421

Construction

Telephone CablesTelephone Cables

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: Moisture Barrier: A layer of aluminium tape (0.2mm) coated with PE-copolymer 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

Telephone CablesTelephone Cables

  

Aabbreviations

LAP (CAP): Bare Aluminium tape + PE sheath

LAPSP (CAPSP): LAP sheath + steel tape armour + PE sheath

LAP (ALPETH): 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

Electrical Properties

Nominal Conductor Diameter mm 0.4 0.5 0.63 0.9
Conductor Gauge Size AWG 26 24 22 19
Maximum Average DC Resistance Ω/km / Ω/mile 140/225 87/140 55/88.6 27.0/43.4
Maximum Individual DC Resistance Ω/km / Ω/mile 144.2/232 89.5/144 56.5/91.0 28.0/45.0
Minimum Insulation Resistance @500V DC MΩ.km / MΩ.mile 1600/1000 1600/1000 1600/1000 1600/1000
Maximum Average Resistance Unbalance % 1.5 1.5 1.5 1.5
Maximum Individual Resistance Unbalance % 5 5 5 5
Average Mutual Capacitance nF/km / nF/kft 48.5-54.0 /14.8-16.5 48.5-54.0 /14.8-16.5 48.5-54.0 /14.8-16.5 48.5-54.0 /14.8-16.5
Maximum Individual Mutual Capacitance nF/km / nF/kft 57/17.4 57/17.4 57/17.4 57/17.4
Maximum Individual Capacitance Unbalance pair-to-pair pF/km / pF/kft 145/44 145/44 145/44 145/44
Capacitance Unbalance RMS pair-to-pair pF/km / pF/kft 45/13.7 45/13.7 45/13.7 45/13.7
Maximum Individual Capacitance Unbalance
pair-to-ground		 pF/km / pF/kft 2625/800 2625/800 2625/800 2625/800
Maximum Average Capacitance Unbalance
pair-to-ground		 pF/km / pF/kft 574/175 574/175 574/175 574/175
Maximum Conductor Loop Resistance @20°C Ω/km / Ω/mile 300/482 192/309 114/183.6 60/96.4
Impedance @1KHz Ω 994 796 660 445
Impedance @100KHz Ω 147 134 125 122
Impedance @512KHz Ω 120 118 117 116
Impedance @1MHz Ω 117 115 114 113
Maximum Average Attenuation @0.8KHz dB/km / dB/kft 1.64/0.5 1.30/0.39 1.04/0.32 0.74/0.22
Maximum Average Attenuation @1KHz dB/km / dB/kft 1.68/0.51 1.35/0.41 1.08/0.33 0.76/0.23
Maximum Average Attenuation @3KHz dB/km / dB/kft 3.18/0.97 2.52/0.77 2.01/0.61 1.42/0.43
Maximum Average Attenuation @150KHz dB/km / dB/kft 11.4/3.47 8.3/2.53 6.2/1.89 4.4/1.34
Maximum Average Attenuation @772KHz dB/km / dB/kft 24.3/7.4 19.4/5.9 15.4/4.7 10.8/3.3
Maximum Average Attenuation @1000KHz dB/km / dB/kft 27.1/8.25 21.4/6.52 17.5/5.33 12.8/3.89
Dielectric Strength          
Conductor to Conductor (3secs) V DC 2400 3000 4000 5000
Conductor to Conductor (3secs) V DC 10000 10000 10000 10000
Minimum EL Far-end Cross-talk-Mean Power Sum          
@150KHz dB/305m / dB/kft 61 63 63 65
@772KHz dB/305m / dB/kft 47 49 49 57
@1.6MHz dB/305m / dB/kft 41 42 43 44
@3.15MHz dB/305m / dB/kft 35 37 37 39
@6.3MHz dB/305m / dB/kft 29 31 31 33
Minimum Far-end Cross-talk-Worst Pair Power Sum          
@150KHz dB/305m / dB/kft 57 57 57 59
@772KHz dB/305m / dB/kft 43 43 43 45
@1.6MHz dB/305m / dB/kft 37 37 37 39
@3.15MHz dB/305m / dB/kft 31 31 31 33
@6.3MHz dB/305m / dB/kft 25 25 25 27
Minimum Near-end Cross-talk-Mean Power Sum          
@150KHz dB/305m / dB/kft 58 58 58 58
@772KHz dB/305m / dB/kft 47 47 47 47
@1.6MHz dB/305m / dB/kft 43 43 43 43
@3.15MHz dB/305m / dB/kft 38 38 38 38
@6.3MHz dB/305m / dB/kft 34 34 34 34
Minimum Near-end Cross-talk-Worst Pair Power Sum          
@150KHz dB/305m / dB/kft 53 53 53 53
@772KHz dB/305m / dB/kft 42 42 42 42
@1.6MHz dB/305m / dB/kft 38 38 38 38
@3.15MHz dB/305m / dB/kft 33 33 33 33
@6.3MHz dB/305m / dB/kft 29 29 29 29
Nominal Insulation Thickness mm 0.175 0.2 0.26 0.3
Nominal Insulated Conductor Diameter mm 0.75 0.9 1.15 1.5

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