Arc Flash, Coordination and Short Circuit Studies at Three Manufacturing Plants, Temple, Grand Prairie and Humble (2019-2021)

Plants change faster than their one-line diagrams. The three studies on this page, done from 2019 to 2021 in Temple, Grand Prairie and Humble, each began with the question of what was really still connected.

Temple: a plant that had changed around its gear

The Temple plant makes consumer and commercial plastic bags. Two utility feeds supply underground feeders that serve the facility. Over the years, changes to the plant left abandoned electrical gear in place, and the switchgear still in service feeds several production lines that extrude plastic film, part of which is made into bags and packaged on site. We worked from the owner one-lines and from walkdowns done by our engineers together with the plant electrical contractors, so the model would match what was energized and not what was drawn. We evaluated the coordination and recommended configuration changes where they were warranted. The report, issued in December 2019, requires that settings and field configuration always match the settings document and one-lines, and that any change be reported so the incident energies can be recalculated.

Grand Prairie: one transformer, our own walkdown

The Grand Prairie plant, studied in March 2021, takes two utility feeds at 12.47 kV into its primary switchgear, stepped down by a single transformer. Protection is by fuses and circuit breakers with no protective relays. All system data came from a walkdown by our engineers. No setting changes were proposed, and the report asks that the settings be confirmed in the field under engineering supervision.

Humble: two buildings at 34.5 kV

The Humble site makes pressure control equipment for the oil and gas industry. We issued two reports in spring 2020. The main facility takes one utility feed at 34.5 kV, stepped down by four transformers, and has an on-site generator. A separate rubber mixing and manufacturing building has dual 34.5 kV utility feeds and two step-down transformers. The one-lines, utility data and walkdowns came from the electrical contractor. Not every breaker model number reached us, so the second report requires that breaker models and settings be checked before the labels are applied.

Five years later we updated both Humble studies, and that work is described in the 2025 arc flash updates.

Same method, different starting points

All three models were built in ETAP with cable lengths and sizes, transformers and panels, and the incident energy followed IEEE 1584-2018 with the worst case used for the labels. The difference was where the data came from: our own walkdown, a joint walkdown with the plant contractors, or a contractor walkdown that we reviewed.

Related services

For the modeling side, see our page for arc flash study services. For field data collection, see walkdowns and as-built drawings.