We had a contractor do radon abatement, which involved adding a fan to pump air out from under the slab. They decided to power this fan by hard-wiring an extension cord. There is a disconnect switch in a weatherproof box on the outside of the house. The wire going off to the left in this picture leads to it. The 2x4s continue for several feet in both directions, so the wire isn't actually hanging in free space.
Is this normal? Should I have a licensed electrician do something about it?