Gas Turbine-Generator Area Classification

[ilan7]

As far as I know, large generators (over 2 MW) are certified for Zone 2 (Class I Div. 2) only. No Generators for Zone 1 or Zone 0.
I’m wondering how the code deal with generator attached to a Gas Turbine inside a close room. The Gas turbine fed by natural (or other flammable gas) and the generator has to be attached to the turbine. The room has to be classified as Zone 1, and there are no generators for Zone 1. How does we allowed to install a generator inside a gas turbine building?
Thanks