WHILE IN CRUISE DURING A CROSS COUNTRY FLIGHT, THE AIRPLANE LOST TOTAL ELECTRICAL POWER. THE FLIGHT WAS CONTINUED TO ITS PLANNED DESTINATION. WHILE IN THE PATTERN, THE LANDING GEAR WAS EXTENDED AT 95 KNOTS INDICATED AIRSPEED. DURING THE LANDING, THE LEFT MAIN GEAR COLLAPSED AND THE AIRPLANE SKIDDED INTO A CONSTRUCTION SITE. THE AIRPLANE IMPACTED CONSTRUCTION MATERIAL AND THE RIGHT MAIN GEAR WAS TORN AWAY FROM THE RIGHT WING STRUCTURE. POST ACCIDENT EXAMINATION OF THE AIRPLANE'S ELECTRICAL SYSTEM REVEALED THAT A BATTERY WIRE LEADING TO THE ALTERNATOR HAD FAILED NEAR THE ALTERNATOR. THE LANDING GEAR WAS TESTED WITH NO ANOMALIES NOTED. THE PILOT OPERATING HANDBOOK STATED THAT THE EMERGENCY GEAR LEVER MUST BE HELD IN THE DOWNWARD POSITION FOR EMERGENCY EXTENSION. THE PILOT OPERATING HANDBOOK ALSO STATED THAT AN AIRSPEED OF 87 KNOTS SHOULD BE ATTAINED BEFORE TRYING TO EXTEND THE GEAR DURING AN EMERGENCY EXTENSION.