On June 5, 1999, at 1225 hours Pacific daylight time, a Beech A-36, N126GL, landed gear up on runway 16R at the Van Nuys, California, airport. The airplane, operated by the pilot under 14 CFR Part 91, sustained substantial damage. The private pilot/owner was not injured. Visual meteorological conditions existed for the personal flight that departed the Van Nuys airport at 1100, with a stop at the Oxnard, California, airport. The flight was scheduled to terminate at the Van Nuys airport. No flight plan was filed. The pilot had gone to another airport to practice takeoffs and landings and test the mode C transponder. After departure from the alternate airport, he noted that his navigational equipment was not working properly. He stated that he was not concerned with this as he was familiar with the area. On approach to the accident airport he noted that he was not receiving radio calls from the tower. He lowered the gear, obtained a three green light indication from the landing gear, and then lost electrical power. He reported that he received a green light from the tower for landing. On the landing rollout the gear collapsed. Tower personnel reported that the airplane entered the traffic pattern for runway 16R on a right base, with no radio communication. They attempted to communicate with the accident airplane and when they received no response they flashed a green landing light signal clearing the pilot to land. Tower personnel did note that they saw the landing gear down, but could not tell if it was in the locked position. In an interview with a Federal Aviation Administration (FAA) inspector, the pilot stated that after departing from Oxnard, no discrepancies were noted until he was over Simi Valley and lost all of his radios. He stated that he lowered the landing gear and saw three green lights, and then he had a total electrical failure. The pilot reported that he continued his flight to Van Nuys and then circled west of the airport waiting for a green light from the tower. The pilot stated that after receiving the green light indication from the tower, he "thought the landing gear was in the down and locked position." The FAA inspector stated that during the interview the pilot did not make reference to the Pilot's Operating Handbook for emergency procedures to circumvent the electrical problem, or manual extension of the landing gear. The FAA inspected the battery and found it indicated 6 volts. The pilot reported that after the engine is started from the battery he manually switches the alternator to the on position. In the interview with the FAA, the pilot could not recall if he had turned the alternator switch to the on position. Visual inspection of the alternator circuit breaker revealed that it had not been tripped. The FAA tested the alternator and found it to operate with no discrepancies. The pilot was interviewed by the airport police and stated that he lost his navigational system and then radio communications. He reported that he rocked his wings back and forth, was given a green light from the tower to land, and assumed that the landing gear was down prior to the electrical failure.