I've built a powder coating oven using 2 oven heating elements...
Question: I have a 4 wire 220v A/C circuit installed by an electrician. Color codes are B/W/R/G.

I understand the green is the ground, White is neutral,Blk is 110v and red is 110v.

The controller (switch) is 3 terminal in a triangle.

Now the question:
If I hook the white to the switch and to one side of the heating elements.
Can I hook both the red and the black to the remaining terminal and get the 208 that I need?

Thanks.

You are all over the place. 220 V.. 208 V.. Which is what you have and which is what you need?

Need more info on the 3 terminal triangle switch.

If you connect the white (Neutral) to the switch, and it connects to a hot wire, you will have created a dead short.

The neutral feed to the unit will be for a return for any 120 volt devices on the unit, such as pilot lights, etc.

The neutral will not connect to any heat element, unless the heat element is rated for 120 volts. The heat elements should be rated for the higher volts.

Now elements can be rated 208 v,220v, 230v,and 240 volts. There are elemnets rated for each voltage and others that are rated for all the voltages combined.

To switch 208-240 volts to a heat element, there are a total of 4 wires, two input into the switch, and two output from the switch to the element.

I do not think the 3 terminal switch you have will work. Can you provide more info on the switch? Or did I help you understand what you need from here?