/images/PowerCableUpdate.jpg/images/southwire_100x70.jpgJacket Repair: How Do You Fix It?JktRepairHowDoYouFixIt.htmTake cable jacket damage seriously – but don’t over-react to cosmetic blemishes.
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Jacket Repair: How Do You Fix It?

Take cable jacket damage seriously – but don’t over-react to cosmetic blemishes.

Cable jackets lead a hard life. They take most of the stress of transportation, on-site handling, and installation. And sometimes they show damage.

“The question is, what is safe to repair, and how do you go about it?” says Jim Bright, manager of industrial products for Southwire’s Western Region. “There are some rules of thumb that can help to make the distinction.”

First, don’t worry too much about minor cosmetic damage. The metallic shield under the jacket is at or near ground potential, so the jacket isn’t really part of the insulation system of the cable. The jacket is strictly for mechanical protection and to keep out moisture.

However, do check carefully for damage that exposes the metallic shield. If you can see the shield through a jacket break, it’s probably better not to attempt a repair. Even without a break, deep indentations may also be signs of potential trouble. If you’re not sure, check with the cable manufacturer.

Several jacket repairs are available

Here are the most common jacket repair methods:

Cold-shrink sleeves

These rubber sleeves come pre-stretched on a removable core. Slide the sleeve over the cable, and pull out the core. The sleeve squeezes onto the cable and maintains a steady pressure as the cable expands and contracts with temperature. No special tools are required. Because the sleeve is a tube, one end of the cable has to be accessible for installation.

Heat-shrink (heat-recoverable) sleeves

Like cold-shrink repair sleeves, heat-shrink plastic sleeves require access to one end of the cable. When heated with a heat-gun or torch, these plastic sleeves contract to form a tight fit against the cable. After the installation heat is removed, the sleeve doesn’t change size, so if the cable shrinks in extreme cold conditions, the sleeve may loosen.

Heat-shrink wrapping

If you don’t have access to a cable end, you may need a heat-shrink wrap-around jacket repair kit. Some versions are printed with a pattern of dots that disappear when the proper shrink temperature is reached. Without the dots, some judgment is required to get a proper fit.

Hand-wrapped tape repair

A very basic jacket repair method is to hand-wrap the cable with a flexible, self-bonding rubber tape, then a vinyl insulating tape. A typical application consists of two layers of rubber tape, overlapping half the width of the tape. Cover the repair with one layer of vinyl insulating tape, again overlapping half the width of the tape.

It’s better to avoid damage

"Although jacket damage can frequently be repaired, it’s better to avoid it in the first place," Bright says. “Much cable damage occurs on the job site. Avoid dragging the cable across the ground, and use specialized handling equipment wherever possible. Finally, protect cable jackets from scrapes during pulling by using an installation cone where the cable enters the conduit.”