NEC and IEC Explosion Proof Standards

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swesley

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I am looking for some additional information on the NEC acceptance (or lack of) the IEC/CENELEC EEx certification for Class I, Div.1 areas. I am looking for liquid flow meters with 4-20mA output for use in subsurface vaults determined to be Class I Div. 1 areas, but am very limited on manufactures. I have found several in Europe with the EEx "ia" IIB T6 certification but understand that NEC does not recognize this for use in the U.S.? Would like to get any thoughts or further clarification. There seems to be a great deal of "confusion" on the issue.

Thanks in advance for any feedback.

Steve.
 
Re: NEC and IEC Explosion Proof Standards

IEC/CENELEC "EEx" certifications are not acceptable.

The marking requirement is for "AEx" which means the product was certified per one of the various ISA 12 series standard. See 505.9(C)(2)(3)
 
Re: NEC and IEC Explosion Proof Standards

I should add there is no provision for using "Zone" rated equipment in Division 1. There is a general provision in 501.1 for using equipment marked per 505.9(C)(2) in Division 2.
 
Re: NEC and IEC Explosion Proof Standards

Then the next question would be whether the AEx is OK in Class 1, Div. 1 areas or whether it is applicable in Zone 0-2 method areas only.

SW
 
Re: NEC and IEC Explosion Proof Standards

meaning that Zone rated equipment could be used in Div. 1 areas as there is no provision
 
Re: NEC and IEC Explosion Proof Standards

Now that we have that out of the way, you are really trying to install per 504 (Intrinsically Safe Systems) anyway. You probably could get away with it with appropriate documentation. "AEx" that is, not "EEx."

"Ex" (IEC) and "EEx" (CENELEC) certified products are not required to pass "ordinary location" standards, "AEx" (NEC) products are. The truth is "Ex" and "EEx" probably could 99 per cent of the time, but they aren't tested for it.
 
Re: NEC and IEC Explosion Proof Standards

Originally posted by swesley:
meaning that Zone rated equipment could be used in Div. 1 areas as there is no provision
Click to expand...
No, there is no provision for using Zone rated equipment in Division 1 at all.
 
Re: NEC and IEC Explosion Proof Standards

And EEx and Ex certified equipment is installed in Class I, Div.1 and Zone 0-2 equivilent areas throughout the rest of the world, it would be nice if the U.S. would recognize the equipment as suitable for use. For now, I will continue the search.
This has been a good discussion, I do appreciate your feedback, just stumbled upon the mikeholt website and saved in my favorites immediately. Excellent resource.

Steve Wesley, P.E.
Environmental Engineer
 
Re: NEC and IEC Explosion Proof Standards

The NEC recognizes two different classification means for hazardous areas. The division method we typically use here and the zone method typically used overseas. An area can be classified by one method or the other, and adjacent areas can be classified by another means. For some reason using the zone method requires a PE to sign off on the area classification which may be why it is less commonly used.

Equipment (such as a flow meter) on the other hand has to be listed or approved by an agency such as UL or FM as being suitable for use in the area or zone.
 
Re: NEC and IEC Explosion Proof Standards

If you are an IEEE member and go to this site you will find one of my papers (do an author search) showing how the NEC "Zone" system is NOT the same as the CENELEC system.

Its now a bit dated (1997) but its one of the reasons we have "AEx" marking. (See the last section). The CENELEC "ATEX Directive" has also reduced the differences a bit with regard to marking, but most of the differences noted are still valid.

Art 505 is actually a "force fit" and not a true adaptation of IEC. Its is one of the reasons a PE needs to supervise the work.
 
Re: NEC and IEC Explosion Proof Standards

Thanks again for the information and clarification, it was very helpful. I did find a meter with FM Class I, Div. 1 approval on both meter and transmitter moments ago made by Kobold Instrumentation. Waiting to hear what they are going to charge me for this thing.


Steve.
 
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