Dead 30 amp circuit/wiring question
I'm hoping someone can give me some guidance, although I will have an electrician do the work. I bought a treadmill and checked the circuit panel for the outlet I plugged it into. The circuit for the outlet is actually two circuit spaces connected together with a 30 amp circuit breaker. The treadmill outlet is the ONLY thing connected to the circuit.
After about the fifth use, the treadmill apparently cooked the breaker. It didn't even trip the breaker: it just died. I checked the outlet and discovered it's rated at 15 amps, and the wiring looks to be 14/2.
It seems I need to run 12/2 line from this outlet back to the panel and replace the 14/2 wire. However, I'm not sure what to do with the two spaces in the panel. Do I remove the 30 amp breaker and just use one space for the 20 amp line and leave the other space open? That seems to make the most sense. I guess i'm mostly confused as to why a 30 amp breaker was hooked up with 14/2 wire.
Thanks in advance for your help!