beamtoolengineer
Member
- Location
- Georgia
- Occupation
- Structural Engineer
Hey all, I'm a structural engineer who occasionally works on substation design. My day job is foundations and steel, but I've always been curious about the grounding side of the projects I work on, so I built an IEEE 80 touch/step voltage calculator at grid.fastercalc.com.
It has two analysis paths: the standard closed-form procedure (Km, Ks, Ki, Laurent-Niemann Rg, the whole Section 16 workflow) and a Boundary Element Method solver that discretizes the grid conductors, assembles the half-space Green's function matrix, and solves for the actual current distribution along the grid. The BEM gives you a spatial touch voltage map instead of just a single worst-case Em, and handles two-layer soil, custom rod placement, and fence transfer potentials. You can export PDF reports with all the intermediate calcs, and in BEM mode you get touch/step voltage heat maps with contour lines.
Results track well against the IEEE 80 Section 16 worked example, and BEM Rg lands within a few percent of the closed-form value. But I'm not an EE, and I know enough to know that's a problem. I'd really appreciate feedback from people who actually do this work:
- Does the methodology look sound, or am I misapplying something?
- For anyone who's done fall-of-potential testing — how close does calculated Rg typically get to measured?
- Any conditions where the closed-form assumptions really break down?
Happy to hear "you got this wrong" — that's the whole point of posting. Thanks in advance.
It has two analysis paths: the standard closed-form procedure (Km, Ks, Ki, Laurent-Niemann Rg, the whole Section 16 workflow) and a Boundary Element Method solver that discretizes the grid conductors, assembles the half-space Green's function matrix, and solves for the actual current distribution along the grid. The BEM gives you a spatial touch voltage map instead of just a single worst-case Em, and handles two-layer soil, custom rod placement, and fence transfer potentials. You can export PDF reports with all the intermediate calcs, and in BEM mode you get touch/step voltage heat maps with contour lines.
Results track well against the IEEE 80 Section 16 worked example, and BEM Rg lands within a few percent of the closed-form value. But I'm not an EE, and I know enough to know that's a problem. I'd really appreciate feedback from people who actually do this work:
- Does the methodology look sound, or am I misapplying something?
- For anyone who's done fall-of-potential testing — how close does calculated Rg typically get to measured?
- Any conditions where the closed-form assumptions really break down?
Happy to hear "you got this wrong" — that's the whole point of posting. Thanks in advance.