In the USA over a 13-year period there were 996 wire related aircraft accidents and in Australia over a similar period there were 119. Excluding accidents in private flying and training environments; in both of these countries the agriculture and emergency services sectors were most affected. This is attributed to their increased exposure to the low level wire environment and the distractions they are faced with.
According to the FAA, the average age of the civilian helicopter pilot involved in these accidents is 43.5 years, with over 4,000 hrs of flight time. The weather is typically good and well over 80% of helicopter wire strike accidents occur in daytime with good visibility.
There are both physical and electronic preventative measures nowadays, however there is no substitute for formal training and crew members that are alert and in-sync with each other. In the absence of a formal training course or a refresher, we recommend this HAI video.