Arc flash data collection: what the study engineer actually needs
An arc flash study is only as good as the data behind it, and most of that data lives in the field — on nameplates, inside trip units and in conduit runs no drawing shows correctly. A study built on a one-line from 2009 and "assumed" breaker settings produces labels that look official and mean nothing. This free data sheet gives your electricians and the study engineer one schedule to work from: one row per bus, collected from the source downstream, with the labeled results tracked on the same row number once the study comes back.
First: labels come from the engineer, not the spreadsheet
NFPA 70E requires electrical equipment likely to be examined, adjusted, serviced or maintained while energized to be field-marked with a label (130.5(H) in recent editions — verify against the edition your program follows). The values on that label — incident energy, arc flash boundary, PPE — come from an arc flash risk assessment. For anything beyond the simplest cases that means an incident energy analysis run by a qualified engineer, typically using IEEE 1584 methods in study software.
This template does not calculate those values and you should be suspicious of any free spreadsheet that claims to. Never copy a label from a "similar" panel, and never guess. The difference between 4 cal/cm² and 40 cal/cm² is usually the upstream device's clearing time — which is exactly the data you're collecting here.
What to collect for every piece of equipment
Identification
Equipment ID exactly as it appears on the one-line, equipment type, location, nominal voltage and system grounding. If the field ID doesn't match the one-line, note both — the engineer needs to reconcile it.
The upstream protective device (the most important part)
Incident energy depends on how much fault current is available and how long it flows. The "how long" is the upstream device. Record:
- Device type — thermal-magnetic breaker, electronic-trip breaker, fuse, relay-operated breaker, utility primary fuse.
- Manufacturer, model and frame; sensor or rating plug; fuse class and size.
- Every trip setting as found: long-time pickup and delay, short-time pickup and delay (and I²t in/out), instantaneous, ground fault.
- Whether there's a maintenance switch (energy-reducing maintenance setting) or zone-selective interlocking.
Photograph the settings screen or dials. Settings on the drawings are what someone intended; settings in the trip unit are what will clear the fault.
Feeders and transformers
Conductor size, sets per phase, copper or aluminum, raceway type and length for each feeder. For each transformer: kVA, percent impedance, primary and secondary voltage and connection, and tap. Lengths can be estimated from drawings — just say so in the notes.
Available fault current
Get the utility's available fault current in writing and record the source and date. The template includes one calculation as a sanity check: the infinite-bus fault current of the source transformer, kVA ÷ (√3 × secondary voltage × %Z/100). That's the most the transformer can deliver with a perfectly stiff utility. If the number you were handed is higher, the cell turns red — the data is wrong, go back and get it right. It is not a study value.
Physical data
Working distance (commonly 18 inches for panelboards and low-voltage switchgear — confirm with the engineer), enclosure height, width and depth, bus gap if known, and the electrode configuration. IEEE 1584-2018 models five conductor arrangements — VCB, VCBB, HCB, VOA and HOA — and the choice affects the result. If you're not sure which applies, choose "Engineer to determine" and send photos.
Filling in the label results
When the study comes back, enter each value exactly as issued on the Label Results tab. Equipment ID, voltage and location pull across automatically from the same row on the field data tab, so the register can't drift out of sync with the collection sheet. Columns cover incident energy, arc flash boundary, working distance, PPE or minimum arc rating, limited and restricted approach boundaries, study date and engineer.
Two columns are automatic:
- Label header — DANGER or WARNING based on a threshold you set. Many companies use DANGER at 40 cal/cm² and above; it's a program decision, so the threshold is an input.
- Review due and status — study date plus 60 months (the NFPA 70E maximum review interval), flagged amber inside six months and red when overdue.
An amber "label installed" cell means a study value exists but the label hasn't been put on the gear yet — useful on a turnover punch walk. For the category method and PPE requirements, see our NFPA 70E PPE categories chart and the NFPA 70E approach boundaries reference.
Safety during data collection
Pulling a deadfront to read a trip unit is energized work. Only qualified persons do it, in the PPE and under the permit your electrical safety program requires — or you collect that data during a scheduled outage. Plan the walk from the source downstream so each bus's upstream device is already documented before you open anything below it.
Keeping labels valid
Labels go stale the moment the system changes: a new transformer, a fuse swapped for a different class, a trip setting "adjusted" to stop nuisance tripping, or a utility upgrade. Any of these requires the engineer to update the study before the change is energized. Keep this register with the study and treat it like any other controlled document.
Related templates and references
- Switchgear & transformer startup checklist — arc flash labels are a pre-energization item
- Ground resistance test report
- Panel schedule template
- Electrical JSA template — plan energized work before you open the gear
- Transformer overcurrent protection chart
- Browse all free construction templates
