THE PLT ELECTED TO TAKEOFF TO THE NORTH FROM A 1931 FT GRASS STRIP. THE WIND WAS FROM 080 DEG AT 5 KTS, THE TEMP WAS 93 DEG, & THE DENSITY ALT WAS ABOUT 2925 FT. GRASS ON THE STRIP WAS 4 TO 6 INCHES TALL & WAS WET. THE SOUTH END OF THE STRIP WAS SOFT & WET; THE PLT INITIATED HIS TAKEOFF FROM A POINT WITH 1647 FT OF RWY REMAINING. DRCTLY OFF THE DEP END OF THE STRIP WAS A 32 FT STORAGE TANK WITH A 10 FT WIND SOCK ON TOP. AFTER LIFT-OFF, THE ACFT WAS BANKED TO THE RGT. IT CLEARED A LOWER MAINT BLDG BY A FEW FT, BUT STRUCK PWR LINES (28 & 33 FT AGL), THEN CRASHED. AN INVESTIGATION REVEALED THE ACFT WAS LOADED TO ABOUT 12 LBS BELOW THE 3600 LB MAX ALLOWABLE LIMIT. ACCORDING TO THE PILOT OPERATING HANDBOOK, 1700 FT WOULD HAVE BEEN REQUIRED TO CLEAR A 50 FT OBSTACLE DRG TAKEOFF FROM A DRY, PAVED RWY. DATA PROVIDED BY THE MANUFACTURER INDCD THAT APRX 2340 FT WOULD HAVE BEEN REQUIRED TO TAKEOFF FROM A SOD RWY WITH 6 INCH, WET GRASS. THE PLT'S LAST MED CERT WAS DATED 3/17/87.