FAA 25.1701 — EWIS Definition and Scope

The Federal Aviation Regulation that defines what an Electrical Wiring Interconnection System is and identifies the components in scope of the §25.1700 series.

Technical detail

§25.1701 establishes that EWIS includes the wire conductors and all supporting hardware whose failure could affect electrical performance. Once classified as EWIS, hardware is in scope for design (§25.1703), separation (§25.1707), protection (§25.1711), maintainability (§25.1717), and continued airworthiness (§25.1729).

FAA Advisory Circular 25.1701-1 elaborates the definitions, the components included, and the certification expectations for the regulation.

When it matters

When deciding which hardware in a modification must be assessed under EWIS rules. The boundary is often broader than designers expect — clamps, sleeving, splices, and bundle supports are typically in scope.

Related terms

Electrical Wiring Interconnection System
Every wire, wiring device, and combination thereof installed in any area of an aircraft for transmission of electrical energy between two or more termination points, including supporting components such as clamps, connectors, and bundle hardware.
FAA 25.1707 — System Separation Requirements
The Federal Aviation Regulation that requires EWIS to be physically separated and electrically isolated from other EWIS, aircraft systems, fluid lines, control cables, and heated equipment such that no credible failure can produce a hazardous condition.