Max Grounding-Grid Resistance for the GPR Screen (IEEE 80)

The inverse of the GPR screen: the grid resistance target that keeps the ground potential rise at or below the tolerable touch voltage, max_R_g = tolerable_touch / grid_current. A 200-V touch limit with a 200-A grid current needs a grid resistance of 1.0 ohm or less to clear the IEEE 80 screen without a full mesh/step study. IEEE Std 80 and a qualified grounding study govern.

max_grid_resistance_ohm = tolerable_touch_v / grid_current_a, the IEEE 80 GPR screen GPR = grid_current x grid_resistance solved for the resistance that keeps GPR at or below the tolerable touch voltage.

IEEE Std 80 ground potential rise, solved for the grid resistance, by name.

IEEE 80 is available through IEEE; the ground-potential-rise relation is a published grounding-study screen.

Estimate. AHJ and licensed professional govern.

Field names used by the API: tolerable_touch_v, grid_current_a, max_grid_resistance_ohm

• Resistance target max_R_g = tolerable_touch / grid_current clears the yard without mesh/step analysisIEEE Std 80
• Grid current I_G is the portion of fault current returning through the grid to remote earth, not the total faultIEEE Std 80