Vent: my brother ran a space heater and a microwave off one 16 gauge extension cord in his Denver garage, and the cord melted into the floor mats | Bad Wiring Tales - Pinecone Attack
Melted into the floor mats sounds dramatic but that's just the outer jacket getting soft. A 16 gauge cord at 12 amps or so will warm up, sure, but the melting point on that cheap PVC is way lower than people think. Unless it actually shorted or the copper was exposed I doubt there was real danger. Denver garage in winter probably had it coiled up too, which traps heat way more than running it stretched out.