How Long Does an Arc Flash Study Take?

Most arc flash studies take 2 to 6 weeks from kickoff to final deliverables.

Smaller facilities with clean, verified documentation can be completed in under two weeks. Larger or more complex systems can extend to six to eight weeks. The difference comes down to a few specific factors: data quality, site access, and system complexity. Here is what actually controls an arc flash study timeline.

The Arc Flash Study Process (4 Phases)

1. Data Collection and Scheduling (1 to 2 weeks)

Before any engineering begins, we need access to your facility and your electrical documentation. This includes one-line diagrams, equipment schedules, site access coordination, and a designated point of contact.

This is where most arc flash study delays occur. Existing documentation is frequently outdated after renovations, incomplete, or difficult to verify. When data comes in slowly or requires multiple rounds of follow-up, it pushes the entire project back before the engineering work even starts.

2. Field Survey (1 to 3 days)

The field survey typically takes 1 to 3 days depending on facility size. We collect transformer data, breaker and fuse information, conductor sizes and configurations, protective device settings, and equipment nameplate data.

A small commercial building may take one day. A large industrial facility with multiple services and substations may take several days. Missing or illegible nameplates, locked or inaccessible equipment, and incomplete pre-survey data all extend field time.

It is common for studies to require multiple site visits when critical data cannot be captured on the first trip. Every return visit adds days to the arc flash study timeline.

3. Engineering and Modeling (1 to 2 weeks)

This is the core of the arc flash study process. We build a detailed model of the electrical distribution system and run short circuit analysis, protective device coordination, and arc flash calculations using IEEE 1584-2018.

For a typical system in the range of 50 to 150 buses, this phase takes 1 to 2 weeks. Larger systems or those with coordination issues take longer. This phase cannot be rushed without compromising accuracy or NFPA 70E compliance.

4. Report, Labels, and Review (3 to 5 days)

The final phase includes the PE-stamped engineering report, custom arc flash warning labels for every piece of equipment, and a quality control review before delivery. If mitigation recommendations are required, they are developed and included here as well.

What Actually Delays an Arc Flash Study

Most delays are not caused by the engineering. They are caused by data and access issues.

The most common causes:

• Outdated or inaccurate one-line diagrams
• Missing breaker trip settings or fuse data
• Blurry or unusable equipment nameplate photos
• Locked or energized equipment that cannot be accessed during the survey
• Scope changes after fieldwork begins

When these issues are present, they lead to additional site visits, rework in the model, and extended project timelines.

Garbage In, Garbage Out: Why Data Quality Is Everything

An arc flash study is an engineering calculation, not an estimate. If the input data is wrong, the results will be wrong. That affects incident energy values, PPE requirements, and the arc flash labels applied to equipment. Workers rely on those labels for real-time safety decisions. There is no room for bad data.

This is why data quality is the single most critical factor in an arc flash study, both for accuracy and for keeping the project on schedule. We continuously improve our data collection process and use structured templates that define exactly what is required before the field survey begins. When clients follow this process, data quality improves significantly and so does the project timeline.

What We Find On Site and Why It Affects Timeline

The field survey is often the first time a licensed engineer has looked at the electrical system in detail, sometimes in years. What we find can affect both the arc flash study timeline and the scope of work.

Common findings that add engineering time:

• Overcurrent devices that are over-duty or lack a valid series rating: A breaker that is not individually rated for the available fault current at its location, where no tested and listed series rating combination exists to make it compliant. If the system has been modified since the original series rating was established, the rating may no longer apply regardless of the nameplate rating.
• Incorrectly voltage-rated equipment: Devices installed in a system at a voltage above their rating. This is a code violation that must be documented and flagged.
• SCCR violations from incorrect fuse types: Motor control equipment with a Short Circuit Current Rating that requires a specific fuse type. When the wrong fuse is installed, the SCCR is voided regardless of the nameplate rating.

When these conditions are identified, they must be documented, evaluated, and included in the final report with recommendations. This adds time to the engineering phase, but identifying these issues is part of what a thorough arc flash study delivers.

Do Not Assume Your Existing Arc Flash Study Is Accurate

Having a previous arc flash study or an existing one-line diagram does not mean your system is current. Electrical systems change over time. Equipment is replaced, circuits are added, utility fault current contributions change, and protective device settings are adjusted.

The engineer who created the original study may not have had complete information, or the facility may have changed significantly since the study was done. We routinely find panels missing from one-line diagrams, equipment that no longer exists, and mismatches between drawings and field conditions.

Everything must be verified against what is actually installed. If discrepancies are significant, it adds time to both the survey and modeling phases. It is better to find these issues during the study than after arc flash labels are already on the equipment.

How Zech Engineering Keeps Arc Flash Studies on Schedule

We focus on eliminating the most common sources of delay before they happen:

• Structured pre-survey data collection templates that define exactly what is required before fieldwork begins
• Clear documentation requirements communicated upfront so nothing is missing on survey day
• Efficient field data collection process that minimizes return visits
• Clean, accurate system modeling workflow in SKM Power*Tools that reduces rework during the engineering phase

When the pre-survey process is followed correctly, projects move faster and results are more reliable. That is not an accident, it is a process refined across dozens of arc flash studies. An arc flash study pays for itself when the process is done right from the start.

Typical Arc Flash Study Timelines by Facility Size

• Small commercial building, under 10 buses: 2 to 3 weeks
• Mid-size facility, 20 to 75 buses: 3 to 4 weeks
• Large industrial facility, 75 to 200+ buses: 4 to 6 weeks

Add 1 to 2 weeks if documentation is incomplete, multiple site visits are required, or significant discrepancies are found between existing records and the actual installed system.

Planning Around Your Deadline

If you have a specific deadline, whether it is an OSHA inspection, an insurance audit, a facility opening, or NEC 110.16 label compliance, communicate it early. We can often prioritize scheduling and delivery to meet your timeline. What we will not do is cut corners on the engineering to hit an artificial deadline.

Frequently Asked Questions

Can the coordination study be skipped?

Technically yes, but it should not be skipped. The additional effort is minimal and protective device coordination directly affects incident energy levels. Improving coordination can reduce arc flash hazard levels at specific equipment, which directly affects PPE requirements and worker safety.

Does the study include equipment below 240V?

Under IEEE 1584-2018, yes. Sustainable arcs are possible in three-phase systems below 240V and we include those buses in our calculations. We have always included 208V three-phase panelboards as standard practice, and the 2018 standard now formally addresses this.

Can an arc flash study be done remotely?

We prefer to have eyes on the equipment. Remote studies based solely on provided documentation are possible in limited circumstances, but field verification is always the preferred approach. The gap between what documentation shows and what is actually installed is too common to skip verification entirely.

How often does an arc flash study need to be updated?

NFPA 70E recommends updating every five years or whenever significant changes are made to the electrical system. Equipment replacements, utility changes, new service additions, and protective device setting changes can all invalidate an existing study before the five-year mark.