Industrial Enclosures in a Class 1, DIV II area

[scokim]

Hello. I was told that a "normal" UL Type 4X stainless enclosure is OK to use in a Class 1, DIV II area. Is that true? Also, can I use "normal" components inside of this enclsoure for building the control scheme I need. Meaning, can I use our normal PLC, control transformer, power supply, etc? I realize the devices outside of my enclosure (pressure switches, pressure sensors, etc) must be rated for Class I, DIV II or be instrinic safe (which then I'll need I/S barriers in my panel) but how about the devices INSIDE of the enclosure itself? Where can I specific information of the do's and don't's on Class 1, DIV II panel building?

 

[rbalex]

Hello. I was told that a "normal" UL Type 4X stainless enclosure is OK to use in a Class 1, DIV II area. Is that true? ...

Ocassionally

... Also, can I use "normal" components inside of this enclsoure for building the control scheme I need. Meaning, can I use our normal PLC, control transformer, power supply, etc? ...

"normal" PLC - probably not
control transformer - possibly
power supply - probably not

... I realize the devices outside of my enclosure (pressure switches, pressure sensors, etc) must be rated for Class I, DIV II or be instrinic safe (which then I'll need I/S barriers in my panel) but how about the devices INSIDE of the enclosure itself?

This depends on the Protection Techniques involved but unless the enclosure is explosionproof or purged the internal elements also need to be individually suitable for Class I, Division 2.

... Where can I specific information of the do's and don't's on Class 1, DIV II panel building?

The basic rules are in NEC Articles 500 and 501. These Articles also reference several relevant API, ISA, UL, etc. standards. There are WAY too many considerations to be summarized here.

 

[petersonra]

Ocassionally

"normal" PLC - probably not
control transformer - possibly
power supply - probably not

This depends on the Protection Techniques involved but unless the enclosure is explosionproof or purged the internal elements also need to be individually suitable for Class I, Division 2.

The basic rules are in NEC Articles 500 and 501. These Articles also reference several relevant API, ISA, UL, etc. standards. There are WAY too many considerations to be summarized here.

Most PLCs these days are listed for C1D2. The primary exception is relay ouput cards. Even the HMIs are often listed for C1D2.

The majority of small power supplies made for the industrial control market place are also listed for C1D2. At least the ones I use are.

Extract from Sola SDP brochure.

Approvals EN60950, UL508 Listed, cULus, UL 60950, cURus, CE (LVD
73/23 & 93/68/EEC), (EMC 89/336 & 93/68/EEC). EN61000-3-2,
EN60079-15 (Class 1, Division 2 hazardous location, Groups A,
B, C, D w/ T3 temp class up to 60?C Ambient.) UL60950 testing
to include approval as NEC Class 2 power supply acc. To NFPA
70 art. 725-41 (a)(2).

I can't make a statement about it in general with any certainty but it seems like most of the industrial control transformers rated as having type 3R enclosures are also listed for C1D2.