What is a Safety Wire?

Mary McMahon

A safety wire is a wire attached to a fastener and an anchor point to keep the fastener in place if it starts to loosen. Aircraft, racing cars and bikes, and similar equipment may need safety wiring by law in some cases, and in others, it is strongly recommended. People can use a variety of wire gauges depending on what they are wiring and any legal requirements, and a number of companies make safety wire kits to make this process as easy as possible. Specialty kits for particular applications like aviation are also available and contain components that all meet legal safety requirements.


To install a safety wire, a technician threads a wire through holes in the fastener and the anchor point and then twists the ends to put the wire under tension. Technicians are careful to create tension in the direction of fastening, rather than loosening, so the safety wire will not make the fastener loose with use. The technician will clip the ends, if necessary, to keep them from protruding.

One advantage to safety wire is visibility on a quick visual inspection. Someone checking a system over can be assured that fasteners are in place and tight simply by looking for the safety wires. The inspection should also show that the wires are being held in even tension, without any weak points where the wire or fastener might snap, and it should be confirmed that the wires are not working against the fasteners by pulling in the direction to loosen them.

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Special pliers for working with safety wire are available. They allow people to grip and clip the wire as necessary, with comfortable handles so operators can twist the wire without injuring themselves. They may come as part of a kit with several spools of wire of different gauges. People can also purchase accessories like color-coded wire they can use in different settings as part of their safety procedures.

While people working on hobby projects do not need safety wire, it can be a good idea. Wiring fasteners in place will prevent losses and can make a project safer. Many hobby stores and suppliers carry the necessary equipment for installing safety wires, and customers can receive assistance if they want instruction in how to use this safety tool appropriately and effectively. Machinists and mechanics can demonstrate how to install safety wires on their equipment in group safety workshops or private lessons.

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