Folks, I am guilty of thread-jacking over in the "green room" and was asked to bring the discussion here. The discussion concerned "ductless mini-split" systems, miniature room (or several room) sized heat pumps noted for astounding efficiency (25+ SEER), due to several factors, perhaps chiefly that they do not require backup heat in most US climates - the heatpump can continue to operate efficiently at very low outdoor temperatures. A poster there asserted that: Each ductless system should have its own circuit. And I posted from there: Why ? This is a big issue for me, because I want to add a mini-split for an addition. I'd put the compressor (outdoor unit) near the compressor for my existing heat-pump, which is on a 60-amp circuit (from an old inefficient HVAC) but has only 35-amp labeling and 16 amps running current. So the 12,000 btu/hr mini-split I'm looking at (20-amp breaker and 5.5 amp RLA) could EASILY live on the same circuit. I hate to run another circuit, because it's far from the breaker box and I'm short on spare slots. When the heat-pump dies (it's 15 years old and only 11 SEER) I'd add a second mini-split and that'd handle my whole house, hopefully. If it really MUST be on a separate circuit, I suppose I could run a sub-panel off the 60-amp circuit. The circuit is controlled by a 60 amp double-pole breaker in my main box. I'd run the 60-amp rated wire to two fused service disconnects, one for the old heat-pump (an existing one with 35 amp fuses) and one for the new mini-split (with 20 amp fuses, as spec'ed for the mini-split). Either daisy-chained per usual wiring techniques, or via a blind junction box in the crawlspace; whatever I do, I'd still use 6ga wire, since of course it's a no-no to have any wire on the circuit that can't handle the breaker-size current If that isn't kosher, I'd do as you suggest and run a sub-panel off the 60 amp breaker. It'd have 35 and 20 amp breakers for the two units. Hopefully I can position the sub-panel so as to be close enough to both compressors - I think the service disconnect only needs to be "within sight" and I can easily achieve that. I wonder if it would be a problem that 35+20 is more than 80% of 60 ? Also, the wire going from the 60-amp breaker in the main box to the disconnect for the existing heatpump is 6-2 (IOW, no neutral). I know subpanels are required to keep neutral and ground separate, but I'd have no neutral. Neither does the existing heat-pump have a neutral (just two hots), and it turns out the mini-split has only two hots and a ground also. So hopefully it's ok not to have separate neutrals and ground in the sub-panel if those are the only loads.