Arc Flash Studies for Manufacturing Facilities

Why Manufacturing Facilities Have High Arc Flash Hazard

Manufacturing facilities combine three conditions that produce high arc flash incident energy levels: large motor control centre buses with significant connected load, switchgear fed directly from medium- or high-voltage utility transformers, and electrical systems that have grown organically over decades without system-level coordination reviews. The result is that many Ontario manufacturing facilities have locations where a worker performing energized electrical work without appropriate PPE would face life-threatening exposure.

The key technical factors that drive high incident energy in manufacturing environments:

• Large available fault current. Manufacturing facilities typically have large-capacity utility service transformers — 750 kVA to 3,000 kVA is common — which supply high available fault current at the main switchgear. High fault current means high incident energy at upstream bus locations.
• Slow upstream protective device clearing times. Facilities that have never had a coordination study often have upstream breakers with conservative (slow) time-delay settings that were configured for coordination purposes but significantly increase arc flash clearing time — and therefore incident energy — at downstream locations.
• Large motor loads at MCC buses. Motor control centres feeding multiple large motors have high bus fault current contributions. The MCC bus is frequently among the highest-incident-energy locations in a manufacturing plant.
• Aging electrical infrastructure. Many Ontario manufacturing plants — particularly in the automotive, primary metals, and food processing sectors — have electrical infrastructure installed decades ago, with protective device settings that have never been systematically reviewed against arc flash implications.

High-Risk Work Locations in Manufacturing Facilities

Arc flash studies for Ontario manufacturing facilities consistently identify the following as the highest-incident-energy work locations — the areas where PPE requirements are most stringent and where de-energizing before work is most strongly recommended:

Main Switchgear and Service Entrance Equipment

The service entrance switchgear is typically the highest-energy location in the facility, fed directly from the utility transformer with the full available fault current of the service. At this location, incident energy is determined primarily by the utility transformer size, impedance, and the clearing time of the main breaker — which is often set with intentional delay for coordination purposes. Many Ontario manufacturing facilities with 1,000 kVA or larger service transformers have incident energy levels at the main bus exceeding 40 cal/cm².

Motor Control Centre Buses

MCC buses are among the most frequently accessed energized work locations in manufacturing plants — troubleshooting, testing, and maintenance happen at MCCs regularly. They are also frequently among the highest-energy locations, fed by distribution transformers with high available fault current and downstream of breakers with slow-clearing coordination settings.

Distribution Panels in Mechanical Rooms and Production Areas

Distribution panels throughout the production facility vary widely in incident energy depending on their position in the system and the protective device upstream. Panels close to transformer secondaries tend to have higher incident energy than panels at the end of long feeder runs.

Variable Frequency Drive (VFD) Cabinets

VFD input and output terminals, and the line reactors and bypass contactors in VFD systems, are work locations that require arc flash analysis. VFD applications have proliferated in Ontario manufacturing over the past two decades — production equipment that did not previously have VFDs often had VFDs retrofitted — and arc flash labels at VFD locations are commonly absent from older studies.

Arc Flash Considerations by Manufacturing Sector

Automotive Assembly and Tier-One Suppliers

Automotive assembly and tier-one manufacturing operations are among the most electrically complex manufacturing environments in Ontario, with multiple production buildings, dedicated substation transformers, and high-density MCC lineups. The Stellantis and Toyota assembly plants and their concentrated supply chains in Windsor, Cambridge, and Kitchener represent the upper end of manufacturing arc flash study complexity. Production line modifications at these facilities frequently trigger mid-cycle arc flash study updates by adding new MCCs, changing protection settings, or reconfiguring distribution to new production equipment.

Primary Metals and Fabrication

Steel mills, foundries, and metal fabrication facilities operate extremely large electrical loads — arc furnaces, induction heaters, large rolling mill drives — and high available fault current at their main switchgear. Hamilton's integrated steel operations represent the most demanding arc flash study environment in Ontario, with multiple medium-voltage substations, large synchronous motor installations, and high incident energy levels across extensive switchgear lineups. Arc flash studies for these facilities are major engineering projects requiring specialized expertise in medium-voltage systems.

Food and Beverage Processing

Food and beverage processing facilities are characterized by high-density MCC installations feeding large refrigeration compressors, process equipment, and packaging lines, combined with washdown environments that create unique challenges for arc flash label durability and PPE selection. Facilities in Guelph's food manufacturing cluster — one of Ontario's highest concentrations of food processing operations — often have arc flash study scopes in the 50–80 node range with moderate-to-high incident energy at MCC buses.

Chemical and Petrochemical Processing

Chemical processing facilities add classified area requirements to the standard arc flash study scope. Electrical equipment in Class I or Class II hazardous locations must be documented for both arc flash hazard and area classification. Sarnia's Chemical Valley concentration of petrochemical facilities requires both standard arc flash analysis and hazardous area documentation, typically delivered as an integrated engagement.

Printing, Plastics, and Light Manufacturing

Light manufacturing operations — plastic injection moulding, printing and packaging, light assembly — typically have simpler electrical systems with lower incident energy levels than heavy industrial facilities. These operations commonly fall in the 20–50 node range, with study costs in the $9,000–$16,000 band, and few locations requiring Category 3 or 4 PPE.

What a Manufacturing Facility Arc Flash Study Involves

The standard arc flash study scope for Ontario manufacturing facilities includes:

• Short circuit analysis — fault current calculations at every bus from the utility service entrance through the distribution system
• Protective device coordination study — verification that breakers, fuses, and relays operate in the correct sequence; identification and correction of miscoordination that may be increasing arc flash clearing times
• Incident energy analysis (IEEE 1584-2018) — arc flash calculations at every panel, MCC, and switchgear location, producing incident energy values and arc flash boundaries
• PE-stamped engineering report — sealed by a Professional Engineer licensed in Ontario
• Updated single-line diagram — current documentation of the complete distribution system
• Arc flash warning labels — label files for all locations in scope, compliant with ANSI Z535.4

For a complete description of what each phase involves and what to look for when reviewing the final deliverables, see our arc flash study guide.

Frequently Asked Questions