14 CFR § 25.1701

As used in this chapter, electrical wiring interconnection system (EWIS) means any wire, wiring device, or combination of these, including termination devices, installed in any area of the airplane for the purpose of transmitting electrical energy, including data and signals, between two or more intended termination points. This includes:

Wires and cables.

Bus bars.

The termination point on electrical devices, including those on relays, interrupters, switches, contactors, terminal blocks and circuit breakers, and other circuit protection devices.

Connectors, including feed-through connectors.

Connector accessories.

Electrical grounding and bonding devices and their associated connections.

Electrical splices.

Materials used to provide additional protection for wires, including wire insulation, wire sleeving, and conduits that have electrical termination for the purpose of bonding.

Shields or braids.

Clamps and other devices used to route and support the wire bundle.

Cable tie devices.

Labels or other means of identification.

Pressure seals.

EWIS components inside shelves, panels, racks, junction boxes, distribution panels, and back-planes of equipment racks, including, but not limited to, circuit board back-planes, wire integration units, and external wiring of equipment.

Except for the equipment indicated in paragraph (a)(14) of this section, EWIS components inside the following equipment, and the external connectors that are part of that equipment, are excluded from the definition in paragraph (a) of this section:

Electrical equipment or avionics that are qualified to environmental conditions and testing procedures when those conditions and procedures are—

Appropriate for the intended function and operating environment, and

Acceptable to the FAA.

Portable electrical devices that are not part of the type design of the airplane. This includes personal entertainment devices and laptop computers.

Fiber optics.