N4459R - 1974 Aircraft Aircraft Registration

***This report was modified on August 18, 2015. Please see the docket for this accident to view the original report.*** The operator's improper installation of a supplemental electrical power supply, which caused a short circuit due to inadequate vibration and abrasion protection, which resulted in chafing of the wires, which contacted one another, short-circuited, and caused an onboard fire. Contributing to the accident were the installation of the supplemental electrical power supply system without the supervision of an FAA-certified mechanic, the lack of an onboard means for fire suppression, and the pilot's inability to see the low-conspicuity power lines across the landing approach path until it was too late to take evasive action.