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 I, Division 2, rated accesories inside of typical NEMA 4X enclosure

Class I, Division 2, rated accesories inside of typical NEMA 4X enclosure

Class I, Division 2, rated accesories inside of typical NEMA 4X enclosure

Hi eveyone,

I would like to receive some advice on a particular issue I have with a Control Panel .

I need to provide a Control Panel with a PLC and HMI in an enclosure.

The point is that it is for a Hazardous Location: Class I, Division 2, Group D.

If it's possible to use a NEMA 4X enclosure UL 508 listed but using all elements inside/outside the panel rated for Class I, Div 2? (PLC, HMI, Relays, wiring made of anti flame (flame retardant))

Would it make it safe? It is correct? It's actually possible?

For other considerations, a purge system is not possible to use since there is not pressurized air available in the zone

I would like to use a NEMA 7 enclosure but I am having problems finding a way to use the HMI in the enclosure.

Other considerations: PLC is Allen Bradley Compact Logix and 7" HMI Panel View also from Allen Bradley.

Considering this limitations, what are your thoughts on using a NEMA 4X enclosure with all the elements rated correctly for the hazardous location?

If you know a way to use and put and HMI in a NEMA 7 enclosure I am happy to hear your suggestions.

I appreciate any kind of help and also hope this is the correct place to locate this thread.

RE: Class I, Division 2, rated accesories inside of typical NEMA 4X enclosure

My quick thoughts: I don't think you can use a 4X enclosure - this is dust tight and water tight, not gas tight. This wouldn't be allowed by the NEC. You have to use an explosion proof panel or pressurized. You can also use IS components and proper wiring techniques and/or nonincendive circuits, equipment and components.
We have explosion proof panels with HMI's and PLCs. We use a knob (page turner) to change the pages on the HMI. However, we use the 1756 controllers.
You should review the NEC article 500 and 501. There is a lot of information in there and descriptions of what you can do and can't do.

RE: Class I, Division 2, rated accesories inside of typical NEMA 4X enclosure

Thanks buzzp for your answer.

I will check the NEC articles you mentioned for my reference.

I am interested in the solutions you have used for PLC+HMI in a hazardous location. This knob thing and stuff.

Can you give me more details about it? I read something about it but proper HMI has to be selected since not all HMI can reference PLC trough a pointer register. Or something like that. I am needing a solution and a quote as well so I am also looking for some companies that can do this. If you can give me more detail I'd appreciate it.


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


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