Electrical Short Circuit and Current Overload Tests on Aircraft Wiring

摘要

This document describes the electrical short circuit and current overload teststhat were conducted on wires used in commercial transport category aircraft. This testing was conducted to evaluate the fire potential that may result from electrical faults. Results of this testing showed that circuit breakers provide reliable overcurrent protection and that circuit breakers may not protect wire from ticking faults but can protect wire from direct shorts. It also showed that circuit breakers may not safeguard against the ignition of flammable materials by ticking faults. Preliminary testing also indicated that direct short circuits are not likely to start a fire and that direct short circuits do not erode insulation and conductors to the same degree that ticking faults do. Current overload testing that resulted in complete thermal degradation of the wire was also conducted to compare it with a fire-exposed wire. No differences were seen; however, the conductor of the wire subjected to the fire was more brittle than the current overloaded wire. Further testing along with metallurgical evaluation would be necessary to substantiate this finding fully.