Learn how EPSOL designed a new ground grid using ETAP at an operating steel plant in Mexico

In this presentation, we will show you the procedure and use it to calculate the grounding system using the ETAP software and the finite element method. The proposed design was analyzed to determine whether the merged parameters meet the security conditions necessary for implementation.
By Carlos Moran Ramirez, Project Manager at EPSOL

Designing a grounding system for an old steel facility presents unique technical and operational challenges. EPSOL Energy & Power Systems Solutions was tasked with developing a completely new ground grid for a steel plant in Tlaxcala, Mexico - an industrial site dating back to the 1960s with no existing grounding infrastructure. Using ETAP Ground Grid Design and Finite Element Method (FEM) capabilities, EPSOL carried out a full resistivity study, designed a robust grid layout, validated touch and step voltages, and supported the first stages of on-site implementation.

Epsol Energy & Power System serves the energy and power systems industry, providing services such as project management, construction of electrical substations, charging stations for electric vehicles, photovoltaic system integration, and compliance management with electrical interconnection standards. EPSOL provides the necessary expertise to deal with problems in the distribution and transmission of energy. Their solutions ensure continuity and reliability in the Electric Network.
Grupo Simec, S.A. de C.V. had steel mills and rolling facilities in Guadalajara, Jalisco, and Mexicali, Baja California, both dedicated to manufacturing commercial and structural steel long products, specialty steel bars, rebar, and steel beams. The conglomerate also has plants dedicated to fabricating special bar quality steels (SBQ), commercial structural long products, and rebar in Apizaco, Tlaxcala, and Cholula, Puebla.

Location: Puebla, Mexico

Year: 2022

Designing and building a grounding system for an old steel plant to ensure operator safety

Challenges

  • No existing grounding system.  When EPSOL arrived, the plant only had a few loose steel wires functioning as makeshift ground cables. A complete system had to be built from zero.
  • Aging industrial facility with difficult working conditions. The plant, operating since the 1960s, is covered with iron dust layers and uneven terrain, complicating resistivity measurements and excavation.
  • Demanding soil resistivity campaign. A two-week field effort using the Wenner method was required to take 19 separate measurement points, with heavy machinery needed due to the harsh soil layers.
  • Complex physical installation constraints. Trenches collapsed due to unstable soil, and excavation had to be coordinated with plant maintenance windows while operations continued 24/7.
  • Accurate FEM modeling required. Soil layering, material resistivity, and fault current parameters had to be carefully defined to meet safety thresholds before construction.
  • Exothermic welding considerations. Choosing correct graphite molds for cable-to-rod and rod-to-structure welds was essential to ensure reliable long-term grounding performance.

Which solutions did they choose?

Selected applications

ETAP Grounding & Finite Element Method (FEM)

  • EPSOL used the Ground Grid module to model soil layers, conductor spacing, rod placement, surface materials, and fault current decay.
  • ETAP FEM capabilities enabled detailed evaluation of touch voltage, step voltage, ground potential rise, and overall grid performance.

ETAP Soil Editor

  • Real resistivity measurements were imported into ETAP to accurately recreate the subsoil profile and its effect on safety thresholds.

3D Ground Grid Visualization

  • ETAP’s 3D view allowed EPSOL to visualize the grid in space, rotate it 360°, and prepare the construction team for real-world implementation.

Why do they use ETAP?

Main customer benefits

Accurate modeling based on real resistivity data

  • Field measurements were fully incorporated into the FEM model, ensuring realistic results that met IEEE safety requirements.

Improved precision for grounding conductors and rods

  • ETAP supported selection of conductor sizes, rod spacing, and multiple rod types, including 5/8-inch rods and 2/0 AWG wires used in the project.

Cost estimation of copper materials

  • ETAP enabled early calculation of total conductor length and copper cost—a critical step given global price volatility.

3D visualization supporting construction planning

  • The team used ETAP’s 3D model to anticipate installation challenges and communicate clearly with field crews.

Validation of worker safety

  • FEM results verified that step potential (848.5 V) and touch potential (maximum 3,871 V) fell within permissible limits and were safe for implementation.

Support for long-term plant reliability

  • A properly designed grid ensures safe operation of furnaces, scrap areas, and substations critical to steelmaking processes.

 

Conclusion

By integrating field measurements, FEM analysis, and ETAP’s advanced visualization tools, EPSOL successfully designed a safe and robust grounding system for one of Mexico’s oldest operating steel plants. The project demonstrates how ETAP enables engineers to address real-world constraints - irregular terrain, aging infrastructure, and challenging environmental conditions - while ensuring compliance with grounding safety standards.

What do they think about ETAP?

Customer perspective

ETAP allowed us to evaluate and design the grounding system accurately. After performing real resistivity measurements and FEM calculations, we verified that the proposed grid met all safety conditions. ETAP also helped us visualize how the grid would be built, which was very useful for the construction phase.

By Carlos Moran Ramirez, Project Manager at EPSOL



Videos

Ground Grid Design with ETAP in a Steel Plant in Mexico - EPSOL

A Ground Grid design project is presented in a steel plant in Mexico and the objective is to reduce the step and touch potentials in the area of ​​electric arc furnaces of 50 kA connected to transformers of 13.8/0.6 KV and that in the moment of melting, they create dangerous currents for the workers who operate these furnaces. The project is executed from the field measurements of the resistivity of the ground and the design of the ground grid with the ETAP finite element method (FEM) and the construction of the grid is executed up to the foot of the ovens, thereby reducing said potentials to safe values ​​for the workers, contributing to a safer work area.


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