The pilot reported that he was spraying fields at night, and prior to the accident he had just completed spraying a field. During the transition climb out to the second field, the helicopter struck high tension electrical wires. He felt the impact and knew that he was going to crash. The pilot reported the helicopter was out of control and he was momentarily blinded by the flash from the electrical wires. He regained his eyesight and noted that the helicopter was rolling to the right and flying in a curved direction. After about 2 or 3 seconds, the helicopter impacted the ground. After impact, the pilot unbuckled his seatbelt and exited the helicopter. He reported that the engine was still running and he continued to experience some blindness. The pilot walked a few steps away from the helicopter before his regained his vision. He looked back at the helicopter to make sure there was no fire, and went back to it, and shut it down. The pilot stated that there were no mechanical problems with the helicopter. The National Transportation Safety Board investigator-in-charge interviewed the pilot, he stated that he had been spraying in this area for years and was aware of the power lines in the area.