What can happen to a nicked shield?
A. The braided shield used in Mil Spec Tefzel twisted shielded wiring is constructed of .004″ Dia. tin coated copper wire strands. These strands are easily severed with a very small amount of force. Even when the braid wires remain intact after the use of a razor blade type knife to remove the outer jacket, hidden damage will most likely be incurred to the shield. When a wire is nicked by a blade, the area affected becomes a “stress riser”, meaning that the reduced cross sectional area of the wire at the damage point results in a highly concentrated area of increased bending force. This concentrated bending force (usually caused by the repetitive movement associated with airframe vibration) over time results in embrittlement of the shield wires at the damage site with eventual wire failure. Over time, this means that an intermittent ground fault may occur.
