I have the same situation here, and this is what I found...read on...
Diesel fuel is considered combustible, not flammable. Therefore, a diesel dispensing area is unclassified, and associated electrical equipment and wiring need not comply with the requirements of Chapter 5. But it's common to wire diesel fuel dispensers adjacent to gasoline dispensers. If conduit for the diesel dispenser passes through the Class I, Div. 1 or 2 areas around the gasoline dispenser, the wiring methods and sealing requirements in Art. 501 apply.
I found this at http://ecmweb.com/conference/holt/electric_preventing_fires_gas/
Hopes this helps.