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Hazardous Location Classification Guide

Class/Division, group, T-code, scenario, and source-boundary planning prompts for hazardous classified location review

Free hazardous location planning screen for electricians, plant engineers, and safety professionals who need a structured review prompt before the real classification work starts. Select the hazard type, material row or custom autoignition temperature, and Division basis to see local Class, Group, T-code, Zone-context, wiring-reminder, source-warning, and scenario outputs. Local material groups, AIT rows, scenario boundaries, and wiring rows are source-gap fixtures, not current NEC, NFPA 497, NFPA 499, API RP 500, API RP 505, equipment-listing, or AHJ proof.

Pro Tip: Class/Division and Zone systems are not interchangeable lookup labels. Use the system, code edition, area-classification basis, release grade, ventilation assumptions, equipment listings, and AHJ direction that govern the project.

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Hazardous Location Classification Guide
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How It Works

  1. Select Hazard Type

    Choose from flammable gases and vapors (Class I), combustible dusts (Class II), or ignitable fibers and flyings (Class III).

  2. Identify the Material

    Select a local material row or enter a custom autoignition temperature and group. Verify the row against current standards, SDS data, tested dust data, and project documents.

  3. Specify Hazard Frequency

    Enter a Division 1 or Division 2 planning basis, then confirm the actual release grade, ventilation, process conditions, and area extent with qualified review.

  4. Review Source Boundaries

    Review the local Class/Division/Group, Zone-context, T-code, and wiring-reminder screen with the warnings that keep it separate from a final classification study.

Frequently Asked Questions

They are separate classification systems. Division 1 can cover conditions that a Zone study may split into Zone 0 and Zone 1, and Division 2 often aligns with Zone 2 as context. A final Zone classification still needs the governing code, release grade, ventilation basis, and qualified review.
The local screen compares the equipment maximum surface-temperature code to the entered autoignition temperature. Dust, mixtures, ambient range, equipment listing, dust-layer and dust-cloud temperatures, safety margin, and project requirements still need current source review.
Group D is a common local Class I gas/vapor prompt for materials such as methane, propane, gasoline vapor, and many solvents. Verify the actual group from current NFPA/API/SDS/source data and the equipment marking before using it for design or installation.
Disclaimer: This is a source-aware planning screen, not a hazardous-area classification study, NEC compliance determination, NFPA 497/499 study, API RP 500/505 study, equipment-listing approval, hot-work authorization, energization approval, or AHJ acceptance. Verify every row against current authorized standards, SDS data, tested dust data, project drawings, ventilation and release basis, equipment listings, and qualified engineering review.

Learn More

Electrical

Hazardous Location Source-Boundary Guide

NEC Article 500 and 505 hazardous area classification explained. Class I/II/III, Division 1/2, Zone 0/1/2, gas groups A-D, dust groups E-G, T-codes, and equipment marking requirements.

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