Are you referring to field installing intrinsically safe wiring with barriers and/or isolators? Or are you simply using a piece of equipment that is intrinsically safe?
If you are installing your own IS circuitry, tell me what brand of barriers or isolators you are using, and I may be able to offer some help.
As Bjarney said, the low impedance grounding doesn't refer to earth resistance, but a ground path sufficiently low to allow the barrier to operate should a fault occur in the hazardous location. The design of the barrier will dictate how this is accomplished.
[This message has been edited by Redsy (edited 02-20-2003).]