Put it outdoors, far from the building. The U.S. Consumer Product Safety Commission tells households to use a portable generator outside and at least 20 feet from the house, with the exhaust directed away, and to keep it out of garages, basements, and other enclosed or semi-enclosed spaces even if a door is open. Carbon monoxide is colorless and can kill quickly. A transfer arrangement that is electrically correct will not save anyone if the generator is running in the garage.
CPSC has repeated this guidance in its portable-generator safety materials and in 2026 winter-weather safety tips. Follow the current CPSC page and the labels on the machine if they differ from memory. Do not decide that “just outside the garage door” is good enough if it is still near an opening.
Install battery-operated or plug-in CO alarms with battery backup, as CPSC also advises, and never try to heat the house with a generator, a grill, or a camp stove. The electrical hookup should still be a listed interlock or transfer switch — see the backfeeding page.
This is not a permit calculation, a utility approval, or a substitute for a licensed electrician, HVAC contractor, or the authority having jurisdiction. Panel Headroom is an independent educational site. It is not a utility, a certification body, or a contractor. Electrical and generator work that is done incorrectly can cause fire, shock, or carbon monoxide poisoning. Use the adopted electrical code and manufacturer instructions; pull permits where required.