fly cable

A 7-conductor cable (or pair of 4-conductor cables loomed) to distribute power and control from a hoist controller to each hoist. Also called simply "motor cable." If using a pair of different Twistlock connectors with genders reversed, known as "Double Hubbell" style.

From http://www.tmb.com/faqconn.htm :

What is the pin out on a 7-pin Socapex?

There is no standard wiring on a 7-pin connector for motor control. Normally the center pin, (#5), is used for the ground. However, the pins used for control and the pins used for power vary from rental company to rental company. Usually they are in groups - [1,2,3, control], [4,6,7 power], or [1,2,3, power], [4,6,7 control]. There is no industry standard, so you should always double check the wiring of any equipment that is sub rented and used with your gear. The reason to double check your gear is that 7-pin connectors carry power and control together and there is a potential for harming the equipment or the operator if the wiring configuration is not confirmed.

From http://www.tmb.com/faqrig.htm :