Early suspension insulators had a pretty high failure rate compared to post 1920's units . They would often puncture through the porcelain head sometimes resulting in catastrophic mechanical failure and dropping the line ... Sometimes too they punctured but did not drop the line with the puncture being enough to cause a line to trip the sub station beakers and go out of service . This was a nightmare for line crews as you had to isolate the mysterious fault over miles of line in a remote area with only visual inspection of each suspension string to look for broken porcelain etc . Imagine doing this in winter with snowshoes... this 1912 era OB suspension met such a fate! In this case it likely resulted in the line being dropped and a big headache for some line crew back in the 1920's as you can see the puncture resulted in a hole being melted in the cap and the pin pulling out of this insulator