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An arc flash is an explosive release of energy from an electrical fault: intense heat, light, pressure and molten metal in a fraction of a second. It’s one of the most serious hazards anyone working on or near energized equipment faces. Arc-flash labels tell workers, before they open a panel, how dangerous that equipment is and what protection they need.
This guide explains what the code and standards ask of facilities in Virginia, and what an arc-flash labeling project involves.
What the National Electrical Code Requires
NEC 110.16 requires electrical equipment in other than dwelling units that is likely to be examined, adjusted, serviced or maintained while energized, such as switchboards, panelboards, industrial control panels, meter sockets and motor control centers, to be field-marked with a warning of potential arc-flash hazards. The label must be clearly visible to qualified people before they work on the equipment.
For service equipment rated 1,200 amps or more, the 2020 NEC (which Virginia enforces) also requires the label to show the nominal system voltage, the available fault current, the clearing time of the service overcurrent devices and the date the label was applied. Labels like this have to be kept current as the system changes.
What NFPA 70E Adds
NFPA 70E, the standard OSHA looks to for electrical safety in the workplace, goes further. It calls for an arc-flash risk assessment and equipment labels that include, among other things, the nominal voltage, the arc-flash boundary, and either the available incident energy and working distance or the required PPE category. It also expects the assessment to be reviewed at least every five years, and whenever major changes are made to the system.
OSHA doesn’t adopt NFPA 70E by reference, but it’s widely used as the way to meet OSHA’s general duty to protect workers from electrical hazards, and insurers and customers increasingly ask for it.
What an Arc-Flash Labeling Project Involves
- Data collection: walking the facility and recording the equipment, conductor sizes and lengths, transformers and overcurrent devices from the utility service down to the panels.
- Utility data: the available fault current at your service, from Appalachian Power, Dominion Energy or your cooperative.
- Short-circuit and coordination studies: calculating fault current throughout the system and how fast each protective device clears a fault.
- Incident energy analysis: calculating the arc-flash energy and boundary at each piece of equipment.
- Labels: printed and installed on every assessed piece of equipment.
- Recommendations: often the study finds places where a settings change or equipment change lowers the hazard significantly.
The engineering calculations are performed or reviewed by a qualified professional; the electrical contractor gathers the field data, installs labels and makes the corrections.
Keeping Labels Accurate
A label is only right until something changes: a new transformer, a utility upgrade, a breaker swap, added equipment or changed settings. Build label review into your NFPA 70B maintenance program; maintenance itself matters too, because a breaker that clears slowly from poor maintenance increases incident energy.
Need arc-flash labels or an updated study? Book a visit on our booking page and we’ll scope it with you.
Frequently Asked Questions
Are arc-flash labels required by law?
The NEC, which Virginia enforces through its building code, requires arc-flash warning labels on applicable non-dwelling equipment. OSHA requires employers to protect workers from electrical hazards, and NFPA 70E is the standard most use to do that.
How often should an arc-flash study be updated?
NFPA 70E calls for review at least every five years, and whenever there are major changes to the electrical system.
Does a small business need an arc-flash study?
Any business with employees who may work on or near energized equipment should assess the hazard. The scope can be scaled to the size of the facility.
What’s the difference between NEC labels and NFPA 70E labels?
NEC 110.16 requires a warning (and more data on large service equipment). NFPA 70E labels carry the results of a risk assessment: arc-flash boundary and incident energy or PPE category.
Why Facilities Call Progress and Heritage
We gather field data, coordinate the study, install labels and make the corrections the study recommends. Our licensed, insured, background-checked electricians serve facilities across Lynchburg, Roanoke, Danville, Martinsville and the surrounding counties. See our service, maintenance and compliance.
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