How should electric cables be protected when passing through holes in bulkheads or firewalls?

When electric cables pass through holes in bulkheads or firewalls, using a suitable grommet is the most effective method for protection. A grommet is a circular ring made from rubber, plastic, or metal that provides a protective barrier between the cable and the potentially abrasive edges of the hole. This protection is crucial because it minimizes the risk of chafing or damage to the cable insulation, which could lead to short circuits or electrical failures.

In aircraft, where safety and reliability are paramount, the integrity of electrical wiring is essential. Grommets not only protect the insulation from mechanical damage but also help to maintain the fire resistance of bulkheads and firewalls, as they can prevent the passage of flames and smoke in the event of a fire.

While other options such as wrapping with electrical tape, plastic, or coating with rubber might offer some level of protection, they do not provide the structural support and durability against abrasion that grommets specifically deliver. Additionally, these alternatives may not provide the necessary fire resistance, which is critical in the aircraft environment.