Fahrenheat Ceiling-Mount Industrial Heater - 7500 Watt "fuh 54b" Questions

What gage wire should be used for wiring an FUH 54B heater Use a micrometer to measure the old wire at a place where it is relatively clean and unburnt.

...FUH-54B at Northern Tool and Equipment and installed it this evening. I have a 30 amp double pole breaker installed, and I have 120V at L1 and 120V at L2. The ground is properly connected. After ...