Tolerable Step and Touch Voltage (IEEE 80)
The IEEE Std 80 tolerable step and touch voltages a grounding grid is checked against -- what meeting a grid-resistance target does not guarantee. The crushed-rock surface layer raises the limit via the Cs derating factor, and the limits scale inversely with the square root of the fault clearing time (a faster relay allows more). Touch governs over step.
Formula and source
Cs = 1 - 0.09 (1 - rho/rho_s)/(2 hs + 0.09); E_step = (1000 + 6 Cs rho_s) k/sqrt(ts); E_touch = (1000 + 1.5 Cs rho_s) k/sqrt(ts) (k = 0.116 for 50 kg, 0.157 for 70 kg).
The IEEE Std 80 tolerable step and touch voltage limits with the surface-layer derating factor Cs, by name.
Audience
This tile is built for electricians and the adjacent professions in the Electrical group. The interactive calculator runs entirely in your browser. No account, no fee, no advertising, no tracking.
Related tools
Posture
Rough Logic answers the math question the working professional asks on the job. The site is a calm, fast, ad-free, account-free, ever-free reference. It does not interpret code. It does not replace the licensed professional. It does not store your inputs. The Authority Having Jurisdiction governs all installations and inspections.