Peebee,
Thanks for your input. The client, as a matter of standard procedure, is going to require the NEMA enclosure.
The technicians at the site monitor the air for hazardous conditions before doing maintenance, so changing the batteries will be a pain from the perspective of undoing all...
Could someone please provide me with a reference/standard for use of batteries (12VDC) in a Class 1, Div 2 area - specifically what limitations there might be for placement of a battery within a NEMA 8 enclosure at an outdoor facility? The battery would be powering an intrinsically-safe sensor.