Natural gas generators do not produce as much fumes than natural gas ranges. Gasoline-powered generators can produce carbon monoxide exhaust fumes, which is why it's important to select the ideal location. These are the reasons why utility companies and local codes often have specific requirements for placement. A generator should generally be located at least 5ft from any windows or doors. While some generators are able to be mounted as close as 18inches from the house, it is still important that the generator is at least 5ft away from any air intake areas on the property. It is not advisable to use portable generators in an indoor environment, such as a garage. This type of generator is best placed outdoors, away from windows and doors.