GrrrRooommm ...Roooomm Rooommmmmm

That would be the sound of the generator kicking on after running the electrical wiring from the generator to the transfer switch!
...Close-up of the wiring coming in from the generator to the transfer switch above.

...and here is the transfer switch box shown with the wiring coming in on the left

Finally- you can see the new manual cord reel in front of the wiring and the transfer switch.