When standby generators are installed, they are typically installed outdoors approximately three to five feet away from any structural opening (local regulations may say something different). This is because they can emit exhaust that can be harmful to people and pets. You definitely don’t want that exhaust accumulating in any occupied areas.
The site is one that is close to the fuel supply line and electric service.
As for whether or not the generator can be installed in an attic, basement or other indoor area, building codes are going to determine whether this is possible. However, it is not recommended (and most likely no tallowed) to locate a generator indoors in small commercial and residential applications. The reasons are completely safety-related. In an instance where a generator may be allowed to be installed indoors and the indoor environment is one in which a generator can operate safely (mostly large commercial and industrial applications), building codes are going to dictate what can and can’t be done.
For industrial or commercial indoor generator installation, the following must exist, otherwise outdoor installation is going to be ideal (outdoor should be the first choice, if possible):
- The building must be designed in a way that it can handle ventilation to remove fumes and heat due to exhaust, the fuel source, starting batteries, and lubrication.
- A duct adapter must be placed on the radio.
- Adequate intake flow must be available.
- Fire codes must be followed.
- The insurance company must permit an indoor generator set to be installed.
Even when an installation meets all of the requirements, it can still become a hazard later. For an installation to retain its safety level, regular inspections are needed and the unit has to be regularly maintained to ensure no dangerous conditions develop over time. It can be ideal for a facility to have individuals trained in generator maintenance or to acknowledge that the generator installation company will need to make frequent visits to the facility to continuously ensure the generator is safe.
It is also important to consider the cost. The cost is going to be higher when having a generator installed indoors (large commercial or industrial only). There is much more work that has to be done to ensure that it is safe.
As for attics, basements, and other locations inside homes, particularly large ones, indoor installation is not recommended for the fact that it is dangerous. Building codes for your area also most likely forbid it. In this case, it is best to stick to standard outdoor installation where the generator can operate the way it was made to operate.