Electrical
What this tool does
Class, Division, Zone, Group, and temperature-code reference for NEC Articles 500 and 505. Verify with the AHJ. This page says what the tool is for, in plain language. The working formula stays on the signed-in tool.
When to use it
Open Hazardous-area classification when this is the job: Class, Division, Zone, Group, and temperature-code reference for NEC Articles 500 and 505. Verify with the AHJ. That is usually a loop, a conductor, a raceway, or a barrier you are about to accept or reject.
Step-by-step
- Open Hazardous-area classification from the tool list.
- Fill System, Class, Division, Zone from the instrument, the drawing, or the job record. Use the unit shown beside each field.
- Fill the remaining fields the same way. Skip a field only when the screen marks it optional.
- Run Calculate when that control is on the page, then read every result row and any warning.
- Check the result against the site procedure and the manufacturer data before you change a range, a wire, a setpoint, or a weight.
- This help page is public. Opening the tool still requires a Pro session.
Inputs
- System
- Choose the System that matches the instrument, the drawing, or the job. Choices include Class and Division (NEC 500), Class I Zone (NEC 505).
- Class
- The tolerance class or the hazardous-area class named on the equipment.
- Division
- Choose the Division that matches the instrument, the drawing, or the job. Choices include Division 1, Division 2.
- Zone
- Choose the Zone that matches the instrument, the drawing, or the job. Choices include Zone 0, Zone 1, Zone 2.
- Group
- Choose the Group that matches the instrument, the drawing, or the job. Choices include A, acetylene, B, hydrogen, C, ethylene, D, propane, E, metal dust, F, carbonaceous dust.
- Temperature code
- Choose the Temperature code that matches the instrument, the drawing, or the job. Choices include T1, T2, T2A, T2B, T2C, T2D.
- Unit system
- Imperial or metric. Pick one and enter every other field in that system.
Results
- Result
- The reported value for Hazardous-area classification. Use the unit printed on that row.
- Warnings
- A warning means an entry is incomplete or outside what this tool will stand behind. Recheck the inputs and the site procedure.
Common mistakes
- Using the wrong metal, the wrong insulation column, or a one-way length where the circuit is a round trip.
- Comparing barrier and device parameters that are not from the same certificate columns.
- Applying a fill or ampacity table to a raceway or a wire the table does not cover.
- Do not treat a result from Hazardous-area classification as a substitute for the site procedure or the manufacturer data.
Standards references
These are the standards and public references named on this tool. Clause numbers appear only when the catalog already cites them.
- NEC Article 500 (Class I, II, and III; Division 1 and 2; Groups)
- NEC Article 505 (Class I, Zone 0, 1, and 2; Groups IIA, IIB, and IIC)
- NEC 500.8(C) temperature identification numbers, including the North American subdivisions
Offline and access
This engine can run offline after the server has cached it for the signed-in account.
A free session can read this help page. The tool card shows the name and the short summary. Opening the tool requires Pro.