Peter you are absolutely correct, most times this will not save anything.

The times I have been able to take advantage of this have been for small air conditioning split systems.

Both Mitsubishi and Sanyo make units that the feed goes from the panel to the outdoor condenser, then you bring line voltage from outside to run the indoor section.

Along with this line volt feed between the units you also need to bring two 5 VDC control wires.

I have used 12/4 MC or NM between the two units to handle both voltages. [Linked Image]

Bob


Bob Badger
Construction & Maintenance Electrician
Massachusetts