Split hvac system

[Jrh62972]

I have to wire a 208 v single phase split system unit. I need to feed the condenser with 2 hots and a ground. Then from the condenser into the unit on the inside they are calling for 3 #12 and a#12 ground. The third wire supposingly communicates through voltage. I need to know if I mount a disconnect by this unit or a toggle switch and where does this third wire go

 

[chris kennedy]

3 pole ST switch assuming 20A.

 

[Jrh62972]

3 pole ST switch assuming 20A.

thanks! I never done one like this .

 

[Saturn_Europa]

3 pole ST switch assuming 20A.

+1, just did one last month and that is exactly what we used.

Dont forget 210.63! I have in the past and its a pain to go back and install an outlet after everything is wrapped up.

Welcome to the forum!!