NFPA 70E 2021 requires that arc flash studies be reviewed at intervals not to exceed 5 years, or whenever there is a significant modification to the electrical system that could affect fault current levels or protective device settings. Significant modifications include: adding or replacing transformers, adding large motor loads, changing utility service, or replacing switchgear. Many facilities in Tijuana are operating with arc flash studies that are more than 5 years old and that predate major system expansions — a serious compliance and safety gap.

Incident energy, measured in calories per square centimeter (cal/cm²), is the amount of energy that an arc flash event would transfer to a worker at a specific working distance from the arc source. To put it in physical terms: 1.2 cal/cm² is the threshold at which a second-degree burn begins to form on bare skin. Arc flash PPE categories are defined in cal/cm² ranges — a location with 40 cal/cm² requires Category 4 PPE, which includes a 40-cal arc-rated suit, face shield, balaclava, and insulated gloves. Without an IEEE 1584-2018 study, workers have no way to select appropriate PPE for a specific task and work location.

The arc flash boundary is the distance from an arc source at which incident energy equals 1.2 cal/cm² — the onset of second-degree burn. Anyone within the arc flash boundary must wear appropriate arc-rated PPE. The working distance is the distance from the arc source to the worker's face and chest during a specific task (e.g., 18" for work on a 480V panelboard). The incident energy at the working distance — not the boundary — determines the required PPE category. Both values are calculated per IEEE 1584-2018 and reported in the arc flash study for each work location.

Poor coordination is most commonly caused by: (1) System expansions that added new protective devices without updating the coordination study, resulting in overlapping or conflicting TCC curves; (2) Replacing one breaker model with a different model that has different time-current characteristics; (3) Relay settings that were never properly configured after installation; (4) Changes in utility source impedance that affect available fault current levels, shifting the operating points of all protective devices. In maquiladoras that have grown organically over years, it is common to find coordination deficiencies that accumulated incrementally through multiple expansion phases.

ETAP and SKM PowerTools are the industry-standard platforms for power system studies in the U.S. and Mexico because they implement the full IEEE 1584-2018 and ANSI C37 calculation methodologies, maintain comprehensive equipment databases, and produce output formats that are industry-recognized for engineering review and UVIE inspections. While other software exists, corporate engineering teams and insurance assessors are accustomed to ETAP/SKM formats. Us Tech delivers native model files to clients so their internal engineering teams can review, update, and modify the model as the system changes — eliminating the need to rebuild the model for every future study.

The UVIE (Unidad Verificadora de Instalaciones Eléctricas) inspects installations against NOM-001-SEDE 2012. While UVIE's core inspection is a field verification of the physical installation, the technical file submitted with the UVIE application must include engineering documentation that demonstrates code compliance — including conductor sizing calculations, fault current data, and protective device coordination. Facilities with 13.2 kV medium-voltage service from CFE are also typically required to provide short-circuit study results as part of the substation approval process. Us Tech prepares the complete technical file for UVIE submission as part of our study scope.

For a mid-size maquiladora (100,000–300,000 sq ft) with a complete short-circuit, arc flash, and coordination study scope, typical timeline is 4–8 weeks from field data collection to final stamped deliverables. The largest variable is field data collection: facilities with accurate, up-to-date single-line diagrams and accessible equipment nameplates move significantly faster than facilities where the existing documentation does not match the actual installed system. Us Tech begins with a kickoff meeting to assess documentation quality and set a realistic timeline before any field work begins.

Yes — and this is a key advantage of working with Us Tech. We produce all study deliverables in both English and Spanish, formatted to satisfy U.S. corporate engineering review (NFPA 70E / IEEE 1584 / IEEE 242 framework) and Mexican regulatory requirements (NOM-001-SEDE / NOM-029-STPS / UVIE technical file). Maquiladoras that commission studies from a Mexico-only engineering firm often receive documentation that cannot be understood or reviewed by U.S. corporate teams, forcing a second study. Us Tech eliminates that duplication.