Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Class 1, Div 2 switch in Class 1, Div 1 Area

Class 1, Div 2 switch in Class 1, Div 1 Area

Class 1, Div 2 switch in Class 1, Div 1 Area

I was doing an audit of my plant and found several limit switches in our plant are Class 1, Div 2 but the electrical classification has the plant as Class 1, Div 1 for ethyl acetate. Are these switches okay to use in our plant or should they really be Class 1, Div 1?

RE: Class 1, Div 2 switch in Class 1, Div 1 Area

If the area classification is Cl1 Div 1, devices in that area classification MUST be certified for Cl1 Div 1.

Div 2 devices are permitted to be nonincendive, which is OK for an area which is normally NOT hazardous (div 2).

Div 1 areas should be thought of as the interior of a gasoline tank in a car, i.e. with the headspace filled with air. If a source of ignition is present, ever, there WILL be a fire or explosion with a high probability. Accordingly, switches in Div 1 areas must be either intrinsically safe or protected by an explosion proof housing with poured seal, by hermetic sealing (i.e. with glass), by oil immersion etc. The approved methods of protection are all listed in the appropriate standards.

Many devices are listed as approved for Div 2 by virtue of being nonincendive, but are also built inside an explosion proof housing certified for Div 1. The only difference then is whether or not you need to pour a seal. Approval drawings will come with wiring/installation drawings suitable for each area classification which MUST be followed for the approval to be valid.

RE: Class 1, Div 2 switch in Class 1, Div 1 Area

Check the control drawing for that installation (if there is one). As mm said, there might be additional protection in place allowing them to be used, otherwise they are not safe.


Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close