Can't figure this 3 wire system out or find anything in postal about it

Ac Wiring Colors

3 phase wiring colours : electrical wiring color codes for ac & dc Can't figure this 3 wire system out or find anything in postal about it

Electrical wiring color codes for ac & dc Thermostat wiring wire heat color diagram pump air nest guide common goodman colors honeywell code labels heater aruf handler wires Phase wires nec creativesafetysupply iec

Electrical Wiring Color Codes for AC & DC - NEC & IEC

Nec iec phase coding neutral current voltage
3 Phase Wiring Colours : Electrical Wiring Color Codes for AC & DC
3 Phase Wiring Colours : Electrical Wiring Color Codes for AC & DC

Electrical Wiring Color Codes for AC & DC - NEC & IEC
Electrical Wiring Color Codes for AC & DC - NEC & IEC

Can't figure this 3 wire system out or find anything in postal about it
Can't figure this 3 wire system out or find anything in postal about it