EWIS and Electrical Cables
Wiring as a system, not a single wire
EWIS is the aircraft electrical wiring interconnection system, maintained to a standard wiring practices manual rather than to personal judgement. Understand the components: wire and cable types and insulation (PTFE, ETFE, PVC/nylon), wire gauge and current rating, conductor stranding, identification marking and sleeving, splices, terminals, connectors with contact retention, backshells and strain relief, clamps and standoffs, and bonding and grounding paths.
Know the installation rules: observe minimum bend radius (commonly ten times the bundle diameter), support the loom at regular intervals and more often where vibration exists, protect against chafing with grommets and edge trim, keep wiring clear of hot surfaces and flammable-fluid lines, and form a drip loop so fluid cannot track into a connector. Separate power wiring from sensitive signal wiring, and segregate from high-energy ignition and HF cables. Connectors need the correct insertion and extraction tools; crimp with a calibrated ratchet tool and pull-test the contact; do not rely on solder alone in a high-vibration run.
Traps: assuming a splice is acceptable everywhere (it is not, in many zones and in fuel-tank or pressurised areas), mating the wrong contact size to a wire gauge, over-tightening clamps and crushing insulation, and forgetting that insulation resistance and bonding tests are part of the release.
Rule of thumb: if the loom can rub, sag or be pulled at a connector, it is wrong - support it, protect it and leave a service loop.