You can ground leftover conductors (in this case, we had 4) to make them act as a shield for plain thermostat wire without any shielded protections. Only green, white, yellow, and red wires were used for 24v power and communications at the board. Red and white were 24v, and yellow and green were for communications.

So, we were left with orange, brown, blue, and black conductors that went unused. The plan was to ground those from both sides and leave them open on one end as not to create a ground loop. We planned to run them through the wires in use and ground the unused conductors against the blower with a ring connector. Connecting the conductors in use under some wire nuts prevents double-lugging under the ABCD connectors.

Stripping the unused wires long helps twist them together; they won’t stay long, but it helps to have them start off long to get a solid foundation to work with. Bryan then connected the unused conductors to a higher-gauge stranded wire (#14) with a heat-shrink splice. He ended up doing two separate splices, as there was too much wire for a single splice to work.