Bonded-pair cabling gets high marks

Industry contractors who use Belden Electronic Division's (www.belden.com) patented Bonded-pair cables reportedly experience fewer performance failures and are spending less time troubleshooting and reworking an installation

Industry contractors who use Belden Electronic Division's (www.belden.com) patented Bonded-pair cables reportedly experience fewer performance failures and are spending less time troubleshooting and reworking an installation.

The company conducted a survey of contractors over the July to October 2001 timeframe. The contractors say they use Bonded-pair as well as other brands of cable.

Insulated conductors of the Bonded-pair cables are affixed along their longitudinal axes, resulting in uniform conductor-to-conductor spacing. Belden claims the uniformity means that the bonded pairs can be manipulated and installed without causing performance-robbing gaps between the conductors. Unbonded pairs, on the other hand, gap when manipulated to create an impedance mismatch, resulting in reflected signals.

Belden says its Bonded-pair cables have a reduced bend-radius and higher allowable pulling tensions, above the recommended guidelines of TIA/EIA, to accommodate what the company terms "normal" installation.

In most installations, cable becomes kinked, bent around tight corners, and is tugged on. Often, when this occurs, the technician undoes the kink and moves on, but this can alter the physical properties of an unbonded-pair cable and its electrical properties. But Belden says its Bonded-pair cables are designed to withstand this stress, and their physical properties are not altered during an installation.

Certified contractors who participated in the survey were chosen from Belden's contractor program. Belden reps say the differences between the two types of cable became evident to contractors when they conducted field testing to verify compliance with industry standards. The contractors were asked how much time they would associate with identifying, locating and correcting problems of near-end cross talk, return loss or attenuation. Contractors reported fewer failures using Bonded-pair cables. For example, they reported an average number of 5.06 failures for return loss for unbonded pair cable, vs. an average 1.72 failures for Bonded-pair cable.

Belden calculated the cost of identifying and correcting each electrical failure per 100 drops, and used an average labor rate for networking cable installers of $45 per hour. The contractors reported 14 failures for unbonded cables per 100 drops, compared to Bonded-pair cables, which had an average of five failures per 100 drops. The 14 failures may not all be attributable to the cable, but the corrections would, of course, cost money. On average, using a $45 per hour average labor rate, it would cost $320 to fix 14 cable failures per 100 drops on unbonded cable.

Number of Failures per 100 Drops-Category 6 Cable

Type of failureUnbonded-pair cableBonded-pair cable
NEXT4.651.56
Return loss5.061.72
Attenuation4.411.72
Total14.125.00

Source: Belden Electronics Division

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