The Tuesday fire in a Logan neighborhood house converted to apartments was caused by an electrical problem, authorities say. The blaze was sparked by wiring in the second floor wall, according to Assistant Fire Chief Brian Schaeffer. Overheating in the wiring ignited the sawdust insulation in the century-old building, he said, and the fire will be listed as accidental. Fire damage was mostly in the home’s attic, but there was also damage to the second floor.