Arc Flash Study Updates

Keeping your arc flash, short circuit, and coordination studies accurate as your system changes and standards evolve. PE-led, for facilities across the San Francisco Bay Area and Northern California.

NFPA 70E requires the arc flash risk assessment to be updated when a major modification or renovation takes place, and reviewed at intervals not exceeding five years. We help you stay ahead of that requirement, including on studies originally prepared by another firm.

Why Lifecycle Support Matters

Power systems change over time as tenants move, projects are completed, and equipment is replaced. Without updates:

  • Labels may no longer match actual incident energy levels
  • Protective settings may not reflect new configurations
  • Old studies can give a false sense of security
  • A worker selects PPE from a label that was correct for a system that no longer exists

Lifecycle support turns a one-time project into an ongoing program that keeps people safe and documentation credible. The failure mode here is quiet: nothing looks wrong until someone opens a cover.

 When An Update Is Required
By standard
  • NFPA 70E 130.5 requires the arc flash risk assessment to be updated when a major modification or renovation takes place, and reviewed at intervals not exceeding five years
  • NFPA 70B calls for short circuit studies, coordination studies, and incident energy analyses to be reviewed for accuracy every five years and updated when system changes could affect the results
  • CEC 110.24 requires the available fault current marking on service equipment to be updated when modifications affect it
By event
  • Utility service upgrade, new service transformer, or a change in available fault current
  • Replacement of switchgear, a main breaker, or a distribution transformer
  • Added generation: generators, UPS, or battery energy storage
  • Significant new load from a tenant improvement, lab fit-out, or production line
  • Protective device settings changed during commissioning or troubleshooting
Our Process
  1. Baseline review: We review your current studies, models, and labels to understand scope and quality, and tell you plainly whether the existing model is sound enough to build on.
  2. Change tracking: Together with your team, we identify what has changed since the last study: projects, equipment replacement, utility data, or operating modes.
  3. Model and documentation update: We update the short circuit, coordination, and arc flash models, then re-run calculations where needed.
  4. Labels and settings: We issue revised labels, settings sheets, and documentation for locations affected by changes.
  5. Programmatic review:  We can set up an annual or multi-year review cycle to keep studies aligned with your capital and maintenance plans.
Is Your Study Out Of Date?

Most of this you can check yourself in about ten minutes:

  • Read the date on your arc flash labels. If it is more than five years old, the study is past its review interval
  • Check the year of the report. A study completed before about 2019 was almost certainly calculated with the 2002 edition of IEEE 1584 or an older method, which used a different model than the current one. The methodology section will say which
  • Ask whether the utility has touched your service. A new transformer or a capacity upgrade moves available fault current, and incident energy moves with it
  • Walk the electrical room with the one-line. If equipment names, breaker frames, or trip units do not match the drawing, the model does not match either
  • Ask maintenance whether any breaker settings have been changed. Settings adjusted during troubleshooting are rarely written down
  • Try to find the report. If nobody can produce it, that is itself the answer

Any one of these is reason enough to have the study looked at. Several together usually means the labels in your building are describing a system that has not existed for years.

What We Provide
  • Periodic review of existing studies and models
  • Updates for new equipment, feeders, or reconfiguration
  • Regeneration of labels and schedules where values change
  • Revised coordination curves and settings where needed
  • Summary memos for management and safety committees
  • A written statement of what changed, what did not, and why
Taking Over Another Firm’s Study

Most update work starts with a report somebody else wrote. That is normal, and it is not a problem. We review the prior model for structure and assumptions before touching it, and we tell you what we find rather than quietly rebuilding it and billing for a new study.

What we check first

  • Which edition of IEEE 1584 was used, and whether the results would change under the current one
  • Whether the utility fault current data is current, and when it was obtained
  • Whether electrode configuration and enclosure dimensions were specified or left at defaults
  • Whether the one-line in the report matches the field today
  • Whether assumptions were documented or simply absorbed into the numbers

If the prior model is sound, the update is an update. If it is not, we say so before starting, and explain what would have to be rebuilt and why. You should not learn that from an invoice.

Codes And Standards

NFPA 70E 130.5

The arc flash risk assessment “shall be updated when a major modification or renovation takes place” and “shall be reviewed periodically, at intervals not to exceed 5 years, to account for changes in the electrical distribution system that could affect the results of the arc flash risk assessment.”

NFPA 70B

Since its 2023 edition, NFPA 70B has been the Standard for Electrical Equipment Maintenance, converting its guidance from “should” to “shall.” It calls for short circuit studies, coordination studies, and incident energy analyses to be reviewed for accuracy every five years and updated when system changes could affect the results, and for single line diagrams to be kept accurate and legible.

NFPA 70B is not automatically law. It becomes binding through adoption by a jurisdiction, a contract requirement, an insurer’s conditions, or as evidence under the OSHA General Duty Clause. We mention it because it increasingly appears in specifications and insurance requirements.

California Electrical Code (CEC)

  • CEC 110.24 – available fault current marking on service equipment must be updated when modifications affect it
  • CEC 110.16(A) – arc flash warning marking on equipment likely to be serviced while energized
  • CEC 110.16(B) – service and feeder-supplied equipment rated 1000 A or more carries a permanent arc flash label that includes the date it was applied

That date field in 110.16(B) is one of the most useful lines on the label: it tells you how old the study is without anyone having to find the report. Code references are to the California Electrical Code as adopted in Title 24, Part 3, and requirements vary by code edition and by the authority having jurisdiction.

Programmatic Review Cycles

The five-year interval is a ceiling, not a schedule. Facilities that change every year are better served by a short annual check against a maintained model than by a full re-study every fifth year, which is usually more expensive and always less current.

  • An annual change review, scoped to what actually moved that year
  • A maintained model that stays with your facility rather than being rebuilt from scratch each cycle
  • Label reissue only where calculated values changed
  • Review timing aligned to your capital plan, so study updates follow equipment projects instead of lagging them
  • A standing record of when each area was last reviewed, which is what an auditor or insurer asks for

The goal is that the answer to “when was this last reviewed” is never a search through old email.

Who Performs The Work

Study updates at Apex are performed and sealed by a California licensed Professional Engineer (PE) in Electrical Power Engineering with more than decades of experience on healthcare, institutional, commercial, and industrial power systems.

We are based in Santa Clara, which matters more for update work than for a new study. Updates are usually driven by a handful of specific changes in specific rooms, and verifying those in person is a short visit rather than a travel day.

FAQs

Q: Do we have to redo the entire study every time?
Not necessarily. If changes are localized, we can often update only part of the model and re-label affected equipment, while still meeting code and standard intent.

Q: Can you take over a model created by another consultant?
In many cases, yes. We will review the model first for structure and assumptions, then propose an update plan.

Q: How often does an arc flash study need to be updated?
NFPA 70E requires the arc flash risk assessment to be updated when a major modification or renovation takes place, and reviewed at intervals not exceeding five years. Changes that could affect the results, such as new equipment or a utility service change, are a reason to review it sooner. NFPA 70B applies the same five-year review interval to short circuit, coordination, and incident energy analyses. The five-year mark is an outer limit, not a target, and system changes trigger an update regardless of where you are in the cycle.

Q: Our study is from 2015. Is it still valid?
It is past the five-year review interval, and it was almost certainly calculated using the 2002 edition of IEEE 1584 or an older method. The current edition adds electrode configuration and enclosure dimensions as inputs, so the same equipment can produce a different incident energy result under the two methods. The labels on your gear were calculated a different way than they would be today.

Q: We only have the PDF report, not the model file. Can you still update it?
Often, but it changes the scope honestly. The data tables in a good report plus field verification can let us rebuild a working model. Without the native file, the work is closer to a new study than an update, and we will say so in the proposal rather than discovering it halfway through.

Q: Does a utility service upgrade require a new study?
It requires at least a re-run. A new service transformer or capacity upgrade changes available fault current, which changes both equipment rating adequacy and incident energy. CEC 110.24 also requires the available fault current marking to be updated when modifications affect it.

Q: Do all the labels have to be replaced?
No. We reissue labels only where calculated values actually changed. Replacing labels that are still correct costs money and, worse, trains people to assume labels change routinely rather than meaning something.

Q: What does an update cost compared to a new study?
It depends almost entirely on whether a sound model exists. An update that builds on a verified model is substantially less work than a new study. If the model cannot be located or cannot be trusted, the effort approaches that of a new study, and we tell you which situation you are in before you commit.

Q: Can you set up a recurring review so we do not have to track this?
Yes. We can establish an annual or multi-year review cycle aligned with your capital and maintenance plans, so updates follow equipment projects rather than lagging them.

Who provides arc flash study updates in the San Francisco Bay Area?

Apex Arc Flash Engineering provides PE-led arc flash study updates and five-year reviews, along with short circuit studies, protective device coordination studies, and single line diagram development, for hospitals, laboratories, data centers, universities, manufacturers, electrical contractors, commercial facilities, and public agencies throughout the San Francisco Bay Area and Northern California. We are based in Santa Clara, and we review and update studies originally prepared by other firms.

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