Electrical wiring is vulnerable to damage from a number of threats, but one of the most pervasive and destructive is cord strain. Anytime a wire or cable is stretched, kinked, snagged, or rubbed against another object, the insulation or underlying conductor is at risk for being damaged. While damage to wiring is often visible to the naked eye, there are times when the damage is hidden under the insulation and only becomes apparent after a failure. That is why the use of electrical wire-strain relief is an important design consideration and why those who handle wiring should always place a high priority on incorporating it into their daily work. Below is more information on electrical wire-strain relief and two specific practices to incorporate to prevent wire strain from occurring.
Leave excess wire lengths
Wire strain is prevalent whenever wire runs are too short for the circumstances and temperature changes lead to expansion or contraction. This, in turn, leads to wire being put under stress loads and can cause it to pull free from terminals or break if the tension is strong enough.
To prevent this from happening, leave an extra length of wire in place whenever you run wire for a particular job. Never cut a wire just short in an effort to save money or in the mistaken belief you are lessening clutter. Instead, allowing a few extra inches is a wise decision in the fight against strain. Once you cut the wire, roll a small loop to neatly package the excess wire, and then hold the package together with a cable tie or other fastener. Be sure there is still plenty of slack in the wire to prevent snapping.
Use strain-relief components
Another important way you can protect wiring from excess strain is to utilize strain-relief components. These special components can provide strong protection from damage in a number of ways; below are several components that you may wish to incorporate into your next project.
Grommets and bushings
Often made from rubber, grommets protect wiring from being cut or otherwise damaged at the point of passage through an opening. For example, in an automobile, rubber grommets are used whenever wiring passes through the firewall between the engine compartment and the passenger compartment. The rubber serves to cushion wiring if it pulls against the side of opening, rather than allowing it to rub against metal edges directly. Rubber grommets also can offer some flexibility by allowing wiring to bend gently, if that is a desirable characteristic.
Much like grommets, and used interchangeably on occasion, bushings can serve the same purpose of protecting wiring as it passes through an opening. However, bushings are often made of harder materials, such as plastic or metal, and they also serve to protect the material by which they are enclosed. The rubbing of wiring can not only harm the wire but also damage the barrier through which it passes, and bushings serve to provide extra protection. In addition, bushings also offer an advantage by permitting cable movement through an opening when desired.
These are intended to help immobilize or restrict the movement of wiring in certain critical points along the run of a wire. Strain reliefs are often found at the end of a wire where it connects to another terminal, but they are useful when wiring needs to make a 90-degree bend, for example, or in other situations where damage can occur. Strain reliefs can be manufactured from hard and soft materials, such as rubber, plastic, and metal.
Fasteners or hangers
Another way to protect wiring from being damaged due to strain is the use of fasteners and hangers. These can be utilized in numerous ways, such as elevating wire runs or attaching wiring to other existing structures, such as pipes or other cables. Merely keeping wiring from becoming entangled with other nearby components is useful in preventing strain. Cable ties, hook-and-loop fasteners, and even tape are examples of fasteners that are used to prevent wire strain.
For more information, consult a company that makes materials such as rubber grommets.