Standards
NFPA 70 and the NEC: where area classification comes from
The National Electrical Code, published as NFPA 70, is where the North American hazardous location framework comes from. Every 'Class II, Division 1, Group E' designation traces back to it. Understanding that the classification is a property of your facility — not of any equipment — is the single most useful thing to take from it.
- The NEC defines the Class, Division and Group framework
- Classification describes your space, not the equipment in it
- It is assigned by your engineer and accepted by the AHJ
- Equipment is then selected to match — never the reverse
What the framework describes
The system has three parts working together. Class identifies the kind of hazardous material present — Class I for flammable gases and vapours, Class II for combustible dust, Class III for ignitible fibres and flyings. Division describes how likely that material is to be present in an ignitible concentration: Division 1 under normal operating conditions, Division 2 under abnormal conditions such as equipment failure or container rupture.
Groups then narrow it to the specific families of material, because ignition behaviour varies substantially within a class. Class I splits into Groups A through D; Class II into Groups E, F and G. Temperature codes cap the surface temperature equipment may reach.
Classification is about your facility
This is the point most often inverted. The classification describes the space and the process — what materials are present, in what quantities, under what conditions, and how likely a hazardous atmosphere is. It is a property of your facility, established by studying it.
It is assigned by your own electrical or process engineer and accepted by the authority having jurisdiction. An equipment supplier cannot assign it for you, and no equipment certificate can determine it. Equipment is then selected to suit the classification that already exists.
Why the order matters
Specifying equipment before the classification is established produces work that may have to be redone. A specification built on an assumed Division 2 that turns out to be Division 1 is not a small adjustment — it changes what equipment is eligible.
The reverse error is subtler and more common: choosing equipment first and then describing the area in terms that make the equipment fit. That is working backwards from a product, and the classification stops being an assessment of the hazard.
The zone system
The NEC also recognises a zone system, aligned more closely with the international approach, as an alternative to the Division system. It exists so that facilities working to international practice can classify consistently, and so equipment certified under either framework can be applied appropriately.
The two frameworks are not interchangeable term for term. Where both are in play, the mapping between them needs deliberate attention rather than assumption.
What this means when you specify recovery equipment
PrestiVac manufactures industrial vacuums. We do not manufacture dust collectors, and housekeeping equipment is one element of a dust safety programme rather than the whole of it.
Our listing is CSA Certificate 70122393. The EX1 HEPA line is covered for Class I, Gp. D; Class II, Gps. E, F and G; Temp. Code T3C; the EV EX HEPA line for Cl. II, Div. 2, Gps. F and G only. Certified equipment does not by itself make a facility compliant with any standard or regulation.
Area classification is determined by your own engineering assessment and the authority having jurisdiction. This page explains the framework; it is not a classification of your facility, and it does not replace the applicable code or your Dust Hazard Analysis.
Frequently asked questions
- Who assigns the area classification?
- Your own electrical or process engineer, accepted by the authority having jurisdiction. It is a property of your process and space, and an equipment supplier cannot determine it for you.
- What is the difference between Division 1 and Division 2?
- Division 1 means the hazardous atmosphere is expected under normal operating conditions. Division 2 means it is expected only under abnormal conditions, such as equipment failure or container rupture.
- Does the NEC tell me I need an explosion-proof vacuum?
- It establishes the classification framework and what electrical equipment is suitable in a classified area. Whether housekeeping equipment is required, and how, comes from the combustible dust standards and your own hazard assessment.
Talk to the manufacturer
Get the right explosion proof vacuum for your application.
Tell us what you need to vacuum and where. Our technical team will recommend the PrestiVac model best suited to your material, your classification and how hard you will work it — and because we build every unit ourselves, we can modify it to fit.
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