Toroid Trans/Rec. (TTR) installs over ground/earth conductor on Construction hoists trailing power cable, or on some Hoists the Bus Bars ground/earth conductor. The signal is transmitted over the power cable between the car, base and building speaker com units.  If  there are  spare conductors available in the trailing cable, then it’s preferable to use a SIGCON. (please call or email us for more information) .