How can you make an intrinsically safe system unsafe? Ground it.

If you’ve just done a double-take on that, read the Art. 100 definitions of grounding and bonding.

To keep these systems safe, remove the difference of potential (and thus a flashover danger) from them and the metal objects around them. To do this:

  1. Connect intrinsically safe apparatus, enclosures, and raceways (if metallic) to the equipment grounding (bonding) conductor [504.50].
  2. Bond all metallic objects of the system per 250.100 [504.60].