THE ACFT COLLIDED WITH A POWERLINE STATIC WIRE DURING AN INSTRUMENT LANDING APPROACH. THE PRIVATE PLT WAS INSTRUMENT RATED AND HAD RECEIVED A WEATHER BRIEFING AND FILED AN IFR FLT PLAN. HE COMMENTED TO THE BRIEFER THAT 'IT DOESN'T SOUND TOO GOOD' AND THAT HE WOULD CALL AGAIN IN AN HOUR OR SO. ABOUT AN HOUR AND ONE HALF LATER HE AIR FILED AN IFR FLT PLAN. WHEN HE REACHED HIS DESTINATION HE WAS CLEARED FOR THE ILS APPROACH AND WAS CLEARED TO LAND WHEN HE REPORTED THE OUTER MARKER. THERE WERE NO FURTHER TRANSMISSIONS RECEIVED FROM THE PLT. RADAR SHOWED THE ACFT ON CENTERLINE AND DECENDING TO 400 FT ABOUT 1 MILE FROM THE END OF THE RWY. WITNESSES SAW THE ACFT AT LOW ALT AND SAW IT COLLIDE WITH THE POWERLINE. ONE SAW A BLUE ARC AFTER THE COLLISION. 3 REPORTED AN EXPLOSIVE SOUND AND BLACK SMOKE FOLLOWING THE COLLISION. THE VISIBILITY WAS DESCRIBED AS ONE TO TWO MILES. THE WIRE THAT WAS HIT WAS 78 FT AGL (149 FT MSL). DECISION HEIGHT FOR THE LANDING IS 329 FT AND VISIBILITY ONE MILE. THE ILS SYSTEM HAD BEEN USED SUCCESSFULLY JUST PRIOR TO THE ACCIDENT.