On January 25, 1994, about 1100 hours Pacific standard time, a Beech BE-58, N1082W, landing gears collapsed during landing on runway 28R at Harry Sham Field, Modesto, California. The pilot was conducting an instrument flight rules (IFR) personal flight to Modesto. The airplane, registered to and operated by the pilot, sustained substantial damage. The certificated private pilot, the sole occupant, was not injured. Visual meteorological conditions prevailed. The flight originated at San Francisco International Airport, San Francisco, California, about 1030 hours. The pilot submitted a Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1/2. In the report, he said that shortly after departing San Francisco, under instrument meteorological conditions, the airplane began to experience electrical problems. These conditions rendered the communications, navigation radios, and most of the electrical instruments inoperable. The pilot could hear some instructions from the radar sector controller, but could not respond. He was aware that visual meteorological conditions prevailed at the destination airport and he proceeded towards the airport. The airplane encountered visual meteorological conditions between Livermore and Tracy, California, about 39 miles northwest of Modesto. He entered the traffic pattern, but did not observe the local controller flash a green light for landing. The local controller did so, but the pilot did not see it due to his extended downwind leg. The pilot heard the gear go down as he extended it electrically, but the landing gear down light did not illuminate. He thought that the electrical problem caused the light not to illuminate. The airplane landed on the runway. After rolling out about 75 yards, the landing gear collapsed. The pilot said that he thought about manually extending the landing gear, but was concerned about an imminent electrical fire. His thoughts were to get the airplane on the ground. The pilot also indicated in the accident report that a mechanic had performed a 50-hour inspection 37 1/2 hours preceding the accident. Mr. Tom Rouch, Top Gun Aviation, Inc., said in a telephone interview conducted on June 6, 1994, that he repaired the airplane. During the maintenance repair, he found one of the battery's positive leads extremely corroded. This condition caused an open circuit in the electrical system.