Speaking of extension cords, my brothers house burned completely down back around 2003. The fire originated from the garage. Two days after it happened I was over a close friends house teaching him how to soft solder copper lines for his new master bedroom and bath addition. As I was telling him the story of the fire, an electrical contractor doing the wiring on his addition heard my story and asked if my brother had a garage door opener. I said yes, and he asked if he ran it off of an extension cord. He explained that in the instructions of all garage door openers it clearly states that the opener has to be plugged in to a dedicated circuit, with NO extension cord. He also said the insurance companies look for that as a possible fault of the homeowner, and may neglect to cover any damages if that was the cause. If you look at major appliances like refrigerators and such, there’s a reason that it comes with a short cord, of high gage wire. No extension cords to be added.
i actually plug into my garage door opener outlet above in the ceiling whenever I use my compressor. It’s a 20 amp, all ran with #12 wire