Contractor could have burned down building due to not wiring Industrial Heater to correct specifications

With the recent deep freeze in Pittsburgh I had a customer call me to hook up an Industrial Salamander  style Electric Heater .

He had borrowed from a contractor friend. The only problem the contractor did not have it wired up properly and was using an undersized extension cord and plug. 

The problem this 230 volt heater is 15000 watts which means it draws 62.3 amps and requires a no#6 gauge wire to it hardwired 

The contractor had it wired 1 size lower than required and the extension cord was 2 sizes too small.

The heater ran but then extension cord started heating up. when i got there I rewired the heater with proper no 6 wire straight to fuse box and wire never even got warm.

Contractor claimed that's how he bought unit new with that undersized cord. unfortunate for him the web site clearly says hardwired no 6 wire