DIV2 Installation questions

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Doodz

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Not quite sure about this: Can I install an Ex ia (IS) device/instrument in a DIV2 area without using a zener barrier and connect to a non-rated equipment installed in a safe area? This could mean that if I install an IS device (for DIV1) other than what is specified, could it become unrated entirely, even for DIV2?
 

petersonra

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Doodz said:
Not quite sure about this: Can I install an Ex ia (IS) device/instrument in a DIV2 area without using a zener barrier and connect to a non-rated equipment installed in a safe area? This could mean that if I install an IS device (for DIV1) other than what is specified, could it become unrated entirely, even for DIV2?
Ex ia means the protection method is via a barrier. If you do not have a barrier there is no protection.

Ex stuff is designed for areas classifed using the zone method, so unless it is dual rated, you cannot use ex rated stuff in a div2 area.
 

rbalex

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Bob (petersonra) is fundamentally correct; however, US Zone rated equipment is generally acceptable in Division 2 applications. See Section 501.5.

In reality though, "Ex" marked equipment is in not acceptable at all. It must be marked "AEx" to indicate it has been tested per US domestic standards. See Section 505.9(C)(2)

In addition, an IS installation must be per Article 504 which requires all installations to be per a manufacturer’s control drawing. The control drawing would indicate the necessity for a barrier, as Bob stated.
 

Doodz

Member
Got it. Actually the device is dual rated to CSA (C/US) and CE/ATEX. But, as what I can understand, if the barrier is not installed, it will lose its rating totally.

Follow up questions, if i may. If I got a DIV2 rated device, installed in a DIV2 area and connect it to an un-rated equipment installed in a safe area, are there any other requirements in doing this, something like using approved cables or using conduits? (Please pardon my ignorance.)
 

petersonra

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Northern illinois
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engineer
Doodz said:
Got it. Actually the device is dual rated to CSA (C/US) and CE/ATEX. But, as what I can understand, if the barrier is not installed, it will lose its rating totally.

Follow up questions, if i may. If I got a DIV2 rated device, installed in a DIV2 area and connect it to an un-rated equipment installed in a safe area, are there any other requirements in doing this, something like using approved cables or using conduits? (Please pardon my ignorance.)
IF it actually has a label on the piece of equipment that says it is suitable for Div 2, there are no unusual requirements, other than the need for seals. You would use a wiring method allowed in article 501.4(B) (if a Class I area).

Many electrical products these days are listed as suitable for Div2 areas. As best I can tell, about the only thing that isn't are products that create arcs, such as hard switches. But normal products that don't get unusually hot or create arcs, often are listed as suitable for Div2 areas. And it is not all that hard to find hermetically sealed switches these days that are suitable for Div2 areas.
 

petersonra

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engineer
rbalex said:
In reality though, "Ex" marked equipment is in not acceptable at all. It must be marked "AEx" to indicate it has been tested per US domestic standards. See Section 505.9(C)(2)
Just curious if you know what the difference is between AEx and Ex rated stuff. One would tend to think the physics of the thing would not change just because one crossed a national border.

The other thing is that I cannot recall ever seeing a US installation done to the zone system. Done a fair amount of stuff for zone 1 and 2 that went overseas, but never in the US. Is it just that uncommon?
 

rbalex

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Technically, "Ex" is to general IEC Standards, "EEx" is CENELEC (EU) Standards and "AEx" is US domestic (Generally ISA) Standards.

The product standards are a bit different, but I don't know all the details. One significant difference that I am aware of is that "AEx" is also required to specifially meet the "ordinary location" requirement also. This is UL Category Code "AALZ." ALL "listed," as opposed to "recognized component" or other certifications, must meet this Category Code.

So far, the most dominant US domestic usage of Zone classifcations that I am aware of is on the Alaska North Slope and the pipeline. They use several enclosed "modules" that are Classified Zone 1 would otherwise be Division 1. There is a significant cost savings.

Edit Add: (Don't know why I didn't say this in s the first place) Another common application is on offshore drilling rigs. Again, they have a significant number of Zone 1 locations that would otherwise be Division 1. My personal opinion is this was the group that pushed Zone classification in thefirst place.
 
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petersonra

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engineer
All the off shore US stuff I have done was done doing thr class and division method. Have not run across any zone stuff. Probably won't as it appears my days of doing stuff for the oil and gas industry is over.
 

rbalex

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I know some North Slope facilites use the Zone method from IEEE papers I've seen presented. The dominant advocate for the method in the '90 to '99 cycles was a major offshore drilling company. I was a major opponent at the time but most of my objections have been addressed. I still don't like it too much because there are actually two Zone systems.

In Canada the Zone System is the prefered method - or was the last time I dealt with the Canadian Elecrical Code - it's been a while. The Division system was an "option." The Canadians originally adopted a system nearly identical to CENELEC. I don't know the current implementation.

It would take more space (much more) than I am willing to spend time on to explain my original objections.
 
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