Electrical wires are installed in aircrafts in two ways – open wiring and cable harnessing. Open wiring is when wires are installed without any special enclosing; and cable harnessing is when wires are installed in bundles to create an organized installation. However, cable harnesses for an aircraft should not incorporate more than 75 wires. Also, it should be taken care that the wires are not more than 2 inches in diameter.
Miracle Electronics from India has this article which you will need to consider for the following very important elements while choosing your cables and cable harnesses for usage in aircrafts.
Sufficient slack in the wiring of an aircraft provides ease of maintenance and terminal replacement; and free movement and shifting of movable equipment to perform servicing, maintenance, repairing, and alignment. It also prevents any kind of mechanical strain on wires, cables, supports, and junctions. This is why –
The minimum radius of bends in the wire bundles must not be less than 10 times the outside diameter of the largest wire. However, where the wire is well-supported, the radius may be 3 times the diameter of the wire. There are certain situations when it is not practical to install the wires within these radius requirements. In such cases, the bend should be enclosed in insulating tubing. Another important point to remember is that RF cables should be bent at a radius not less than 6 times the outside diameter of the wire.
Splicing can be done as long as it doesn’t affect the reliability and electromechanical characteristics of the wiring. But, even if this condition is take care of, splicing can only be done if there is engineering approval for the same. However, there are certain limitations that need to be kept in mind –
Parallel wires running within an aircraft are sometimes required to be twisted; for example, in three-phase distribution wiring, wiring in the vicinity of magnetic compass or flux valve, and other wires specified on engineering drawings. The twist should be such that the wires are secured against each other, making the required number of twists per foot. It is important that the wires are checked after twisting for any kind of insulation damage; and if the insulation is torn or frayed, the wire must be immediately replaced.
Wires and harnesses within an aircraft are supported by clamps, making them a very important constituent in aircraft wire installation, which is why we include this section in this blog.
These are only some of the very important considerations of installing wires and harnesses within an aircraft. There is much more to be considered, which is why you need experts for the job, who can take care of not only the installation, but also the protection of wires and harnesses against elements like high temperatures, fluids, solvents, chafing, and movement.