What Is a Run Time?

How long a generator can operate continuously on a given fuel supply. Natural-gas standby generators have effectively unlimited run time as long as utility gas service continues, since they draw directly from the gas line rather than an on-site tank. Propane and diesel units are limited by their tank size — a larger on-site propane tank extends run time but requires more space and periodic refilling. Portable gasoline generators typically have the shortest run time per tank and require the most frequent manual refueling.