The maximum length of a single-mode fiber patch cable can vary depending on several factors, including the specific application, the type of fiber used, and the quality of the cable. However, in general, single-mode fiber patch cables are designed for relatively short-distance connections within a network, typically ranging from a few meters to several tens of meters.

For long-distance transmissions, single-mode fiber cables are usually used instead of patch cables. Single-mode fiber cables can support transmission distances of up to 100 kilometers (62 miles) or even further, depending on the specific fiber type and the quality of the installation.

In summary, while the maximum length of a single-mode fiber patch cable is relatively short compared to single-mode fiber cables used for long-distance transmissions, it is still sufficient for most patching and interconnection needs within a network. For specific length requirements, it is best to consult with a fiber optic cable manufacturer or supplier to ensure compatibility and performance.