Just a question, what is the purpose of linking/attaching 2 x 15 amp breakers together? (They are single 15 amps but joint with a cap on the top)
This configuration would be for a 240 volt circuit.
ok so its 240 volts @ 30amps or 15 amps?
What would you plug into it?
I know a dryer is 240v@30amps
Baseboard heater can't remember?
Circuit amperages are never combined. This is a 15A 240v, or 120/240v, circuit.
Could be an AC, a motor load, electric heat, etc.
if electric heating what is the minimum wire size?
A 15A circuit can be wired with #14. This is the smallest building wire size.
Could be a multi wire branch circuit. Two circuits sharing a neutral wire.