Taking the Old With the New

As networks get faster, cabling to support them needs upgrading. Outside plant networks, most of which run on single-mode fiber optic cable with its almost infinite bandwidth, are rarely in need of upgrading.

On the other hand, premises cabling usually needs to be upgraded. Many networks are still operating over older 62.5/125 micron fiber, now called OM1 fiber. Gigabit or faster networks installed in the last decade may be using 50/125 micron OM2 fiber, which has higher bandwidth with laser sources used in gigabit networks. Of course, many premises networks still use copper cabling in one of the multiple grades sold in the last decade, so those networks would certainly benefit from a fiber upgrade.

With multimode, the fiber choices have multiplied. In the last couple of years, we have been bombarded with two new multi-mode fiber types. OM3 fiber stretched the bandwidth window to accommodate 10 gigabit networks. OM4, with even higher bandwidth, came along to allow 10 gigabit networks to operate over longer distances, although those longer distances claimed by manufacturers may not be supported by networking standards or equipment vendors.

Several fiber manufacturers recently added a new twist: bend-insensitive fibers. These fibers tolerate bends and kinks better without incurring excess loss from the stress on the fibers. Still, other manufacturers question the compatibility of bend-insensitive fibers, at least their versions, with other fibers.

Finally, standards have been approved for 40- and 100-gigabit networks, which adds another option. Do you install a multimode cable plant that uses parallel 10-gigabit channels or single-mode that requires only two fibers per link? Choosing a parallel option requires installing massive numbers of fibers, 12 or 24 per link instead of two, and keeping link optical loss extremely low, probably making a prefabricated, plug-and-play cable system easier to install. Choosing single-mode fiber means fusion-splicing pigtails on the fibers for termination or using prefab cabling.

Choosing which fiber to install used to be easy, but no more. Pushed for an answer, I would probably suggest you design your backbone cabling around OM3 multimode fiber and single-mode fiber. The single-mode fiber is cheaper than kite string or fishing line and does not need to be terminated until you need it. Use the cheaper OM3 fiber with today’s 10-gigabit networks. Since Google has said it will go single-mode for 100-gigabit networks, I’ll bet the price will decrease, so you won’t have to install gazillions of multimode fibers to support parallel 100-gigabit links and can use that cheaper single--mode you so wisely installed.

What do you do with the cables you replace? Since 2002, the National Electrical Code has been calling for the removal of “abandoned cabling” in buildings as a fire hazard. Cable jackets are required to be flame-retardant, but even if they do not burn, they release smoke and hazardous chemicals into the air during a fire, with potentially harmful results. Plus, who knows how they react when they are decades old? Users should be informed that those cables need to be removed.

If the cable to be removed is copper, the high price of copper makes doing so more palatable. While it is still costly to remove, copper can be recycled for a very reasonable payback.

This brings me to recycling. In order to maximize your return on selling scrap cable to recyclers, separate cables by type. The best price is for electrical power cable, obviously, since the copper content is higher than for communications cable. Recyclers grade cable by conductor size, basically larger or smaller than 12-gauge wire. Also, separate communications cables by jacket type. Some recycled plastics can be reused while others are processed for use as fillers or to make structures like park benches. However, the different types of jackets on riser and plenum cable, for example, require segregation for recycling. Fiber optic cable is basically recycled for filler.

Deal with a legitimate recycler, preferably one who owns the machinery to process cable locally, and you will get a better price and assurance that the materials are properly handled. Local governments can help you find them. If you have a big enough load, they will often pick it up for you.

Recycling is good business for contractors. It adds to your green image and to your profit. By assisting your customers to understand the need for removing abandoned cabling and recycling scrap cables, you are helping your customers and building customer loyalty.

HAYES is a VDV writer and educator and the president of The Fiber Optic Association. Find him at www.jimhayes.com.

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