Visual Inspection of Wiring – A Quick Guide (Section II)Author:
Lectromec - Michael TraskosPublished:
This is intended as a quick guide for those performing visual inspections on wiring systems. There is more that needs to be considered than what is covered in this article, but hopefully this can be used as a starting point. Each of items discussed with be addressed in greater detail during this series.
Tools and Equipment
The following tools are recommended for visual inspection of wiring systems:
- Handheld bright white flashlight
- Small mirror on telescoping holder.
All parts of the wiring system are important, but there are areas that should be placed on more frequent inspection intervals. This will be covered in more depth in a future article but as a quick reference, the following factors will place an area higher on an inspection list:
- Exposure to fluids (fuel, de-icing fluid, hydraulic fluid)
- High temperature
- High number of maintenance actions
- High density areas (EE bay)
With wiring, there are three main components for the inspection: Wire connection/termination points, wire insulation, and equipment supporting/securing the wire. Inspection of each of these with a guided and careful inspection will help identify issues before they turn into problems. In this article, we will only cover the inspection of the wire insulation.
It is important to look for more than just a breach to the conductor. Often breaches are not easy to see as they are obfuscated by different insulation failure mechanisms. Items that should be kept in mind when examining the insulation include:
- Cracking, peeling, chafing or flaking
- Heat damage: color change, carbonization, or melting
- Physical damage: chaffing, pinching, or crushing
- Exposure to fluids
It is advisable to replace wire segments with any sign degradation.
In addition to the above considerations for wire insulation inspection, there are a couple points of caution:
- A visual inspection alone is not enough to determine if a system is safe.
- Large bundles can easily hide damaged wires.
- Wire degradation is not easy to spot; additional testing may be necessary.
For complex or aged systems, additional tools and/or analysis are necessary to determine the condition of the wire insulation. Overall, if it does not look safe, you are probably right.