Insulating links have been manufactured since the 1970’s and have been controversial.
They have been controversial as used by plaintiffs to sue the crane companies after a worker was electrocuted or injured. Unfortunately, most of the evidence has been buried after ‘out of court’ deals.
They have been controversial as they were not reliable in all weathers up till 1997 when Insulatus Inc. introduced their product.
They have been controversial as a two-track standards process was initiated after 2004. This has resulted in two current standards with the first being the American National Standard CPLSO 14 and requiring much more stringent testing than the “non-American National Standard” ASTM F2973.
They have been controversial as the sponsors of this later ASTM F2973 has unsuccessfully tried to sue UL and CPLSO to stop the existing standard.
This web site provides some of the evidence to allow a researcher to confirm that only a product made to the American National Standard CPLSO 14 is safe to use on a construction crane in all environments.