Field guide
Arc Flash Labels for Industrial Control Panels
Is a label required?
Yes, and the reason is behavioral: industrial control panels get opened energized all the time. Troubleshooting a starter, tracing a circuit, checking a voltage with production running — that is energized work within the meaning of NEC 2026 §110.16 and NFPA 70E §130.5(H), and it is the daily reality of maintenance on production equipment. Panels that truly are never opened hot are the exception, and a cramped production schedule is usually evidence of the opposite.
What the label shows for this equipment
The label shows the standard fields — nominal voltage, incident energy, arc-flash boundary, PPE level, assessment date, available fault current with date, label ID — with two control-panel specifics. The nominal voltage is the highest the assessment covers (a 480 V feed with a 120 V control transformer means 480 V behind the door). And the values belong at the panel's line terminals, fed from the upstream protective device — which may be several sections of busway or a long feeder away, so the point-to-point fault current at the panel can be much lower than at the service. Configuration is typically VCB; the enclosure correction factor matters in these smaller boxes.
NFPA 70E table-method rows for this class
| Equipment class row | Max fault current | Max clearing time | PPE category |
|---|---|---|---|
| Other 600 V class (277–600 V) equipment | 65 kA | 0.03 s (2 cycles) | 2 |
Rows come from NFPA 70E-2018 Table 130.7(C)(15)(a), cells cross-verified against multiple independent reproductions. If your fault current or clearing time exceeds the row, the table does not apply — an IEEE 1584-2018 calculation is the path, which is what the calculator runs.
Notes specific to this equipment
Three control-panel specifics. First, small enclosures: the IEEE 1584-2018 enclosure-size correction factor concentrates energy in tighter boxes, so a small panel can compute hotter than an open switchboard at the same inputs. Second, long feeders: the impedance between the service and a machine-side panel knocks the available fault current down — the point-to-point path in our fault-current guide is how to find the real number. Third, mixed voltages: control transformers and VFDs inside the panel do not reduce the line-side hazard the label describes. The "other 600 V class" table row above covers many of these panels when clearing is fast.
What to collect before you calculate
Per panel: line-side voltage and phase, available fault current at the panel terminals (long feeders make the point-to-point calculation worth the five minutes), the upstream protective device and settings, enclosure dimensions for the correction factor, and the electrode configuration. While you are at the machine, note the machine disconnect too — it needs its own label, and its numbers differ from the panel's.
Other equipment guides
Get the label numbers for your equipment in the free arc flash calculator — panel specs in, a reviewable record and label preview out. The master field list lives at arc flash label requirements; sizes and stock at the arc flash label template page.
Direct answers
Frequently asked questions
Do industrial control panels need arc flash labels?
Yes, when they are worked while energized — and control panels are troubleshooted hot almost by definition: meter on a terminal, door open, production running. NEC 2026 §110.16 and NFPA 70E §130.5(H) scope by likelihood of energized work, which for an industrial control panel is routine behavior, not an edge case.
The control voltage is only 120 V — does the panel still need a label?
The label is driven by the power circuit in the panel, not the control circuit. A control panel fed at 480 V with a control transformer inside still has 480 V available fault energy behind the door. The nominal voltage on the label is the highest the assessment covers.
Who is responsible for labeling a machine's control panel?
The employer whose people open it. Machine builders may ship a warning, but the NFPA 70E risk assessment — and the detailed label it produces — belongs to the facility where the equipment is installed and serviced.
Source trail
Sources
Standards references identify the applicable document or section where possible. Standards text may require licensed access. Report a factual issue through the process on our corrections page.