The merchandise under consideration is described as high voltage cables. The subject cables are comprised of a 25 meter length of insulated conductor affixed at each end with high voltage electrical connectors. You state that the cables are rated for use at either 66,000 volts or 138,000 volts. The cables are further meant for use in various electrical installations where a large amount of electricity is produced and distributed.
[1] Please importantly note that only the relevant portion of the related is displayed above. You may refer to the said customs ruling for the entire ruling explanation.
[1]. https://rulings.cbp.gov/ruling/N322713