Field guide
Arc Flash Labels for Disconnects and Safety Switches
Is a label required?
Yes, and disconnects are the most commonly missed equipment class in labeling programs. The reasoning goes "it is just a switch" — but a disconnect exists to be operated energized, and it gets opened for fuse checks, testing, and service while hot. NEC 2026 §110.16 and NFPA 70E §130.5(H) scope by likelihood of energized examination, adjustment, service, or maintenance, and a safety switch meets that test by design. If the panel it feeds has a label and the disconnect does not, the program has a hole exactly where hands go.
What the label shows for this equipment
A disconnect label shows the standard fields: nominal voltage, incident energy at the working distance, arc-flash boundary, PPE level, assessment date, available fault current with its as-of date, and a label ID. One detail matters here: the values are computed for the disconnect's line side, fed from upstream — the clearing time comes from the upstream protective device, not from the fuses inside the disconnect itself (those protect the load side). Configuration is typically VCB for enclosed switches.
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
Disconnects sit in the "other 600 V class" table row, which caps at 65 kA and two-cycle clearing for Category 2. The trap is the clearing-time source: a fused disconnect protects downstream equipment through its own fuses, but the label values for working on the disconnect itself are set by whatever protects it upstream — a feeder breaker that may clear far slower than two cycles. That is how a "simple switch" computes to energies well past Category 2. Also note the NEC 110.9 angle: the disconnect's interrupting rating must meet or exceed the available fault current at its terminals, and the label documents that current.
What to collect before you calculate
Per disconnect: line-side voltage, available fault current at its terminals (point-to-point from the service, or the facility study value), the upstream protective device and settings for clearing time, and the fuse class inside for the load-side picture. Disconnects are scattered by nature — a roof, a wall, a machine side — so a simple inventory list with locations pays for itself before the first calculation run.
Other equipment guides
- Electrical panels and panelboards
- Transformers
- Switchgear
- Motor control centers
- Industrial control panels
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
Does a disconnect switch need an arc flash label?
Yes, when it is likely to be operated, tested, or serviced while energized — and disconnects are operated energized by design. NEC 2026 §110.16 and NFPA 70E §130.5(H) scope by likelihood of energized work, and a disconnect exists to be switched.
What PPE category does the NFPA 70E table give for a disconnect?
Disconnects fall in the "other 600 V class" row: Category 2 at up to 65 kA available fault current and 0.03 seconds clearing. Outside those caps, the category comes from an incident-energy calculation.
Is operating a disconnect energized work?
Normal operation of a properly installed and maintained disconnect in normal condition is generally treated as normal operation under NFPA 70E. Opening it up for testing or service while energized is different — that is the work the label exists for.
Source trail
Sources
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