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Standards for Insulating links
ANSI/CPLSO-14
ANSI/UL2737 (Withdrawn)
ASTM F2973
MIL-L-24410 (Withdrawn)
Tests by Independent Organizations
Load Insulator
Miller & Hirtzer
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PAGE 1 Background I have been involved in the testing and evaluation of insulating links for use with load lifting equipment near energized lines now for at least 40 years. My first introduction with the need for testing was my engagement by Bycrus‐Erie a manufacturer of large lift equipment. I issued a joint report on insulating links and boom cages with Dr. Howard Hamilton, past chair of the Electrical Engineering Department at University of Pittsburgh, in the early 80s. in later years I worked on projects for the evaluation of insulating links with Dr. Gerald Whitehead a mechanical engineer and Professor at Louisiana State University. This included the evaluation of several different links. The underlying concern for an insulated link is that it is a life protection device. When placed on a lift device it must perform as advertised in a wide variety of environments having been subjected to a wide variety of mechanical conditions. It is rarely ever removed from the load line once installed and is subjected to overnight conditions of dew, rain, snow and the accumulation of natural and man‐made contaminants in the atmosphere. To be a life safety device it must not allow a lethal current to flow at anytime during its use under any and all conditions of use. One could also reasonably argue that the device must not allow any level of current to flow that would create a shock, lethal or not. A reaction to a shock could cause the user to fall, jump into the pathway of moving equipment or many reactions that one can envision that are potentially dangerous in a variety of workplaces. All my approaches to the test and evaluation of the insulated link or any insulated device used as a life safety device has considered the issues described. This evaluation will of necessity incorporate all of these plus some that are not specifically identified. There are further concerns associated with the use of the insulated link on lift devices. The uninformed user might assume that the insulated link protects all workers in the vicinity of the lift device from a contact. Very few contacts with a power line occur below the insulated link, that is with the load carried below the link. Most of the contacts are above the link with the lift line or any portion of the boom of the lift device. These contacts energize the entire lift device and create a danger zone of step and touch potential to a wide variety of workers in the vicinity of the lift device. I have prepared this analysis based on my experience at the request of Dr. Hugh Pratt from CPLSO.
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