Flex in CL1 Div1 with an IS circuit

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kurt.brinker

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Is it acceptable to run flexible non-metallic conduit in a Class1 Div1 area as long as the circuit is Intrinsically Safe? The install would go as follows
NEMA7 enclosure--short conduit nipple--seal off--flexible conduit--Approved Sensor
 
kurt.brinker said:
Is it acceptable to run flexible non-metallic conduit in a Class1 Div1 area as long as the circuit is Intrinsically Safe? The install would go as follows
NEMA7 enclosure--short conduit nipple--seal off--flexible conduit--Approved Sensor
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504.20 Wiring Methods. Any of the wiring methods suitable
for unclassified locations, including those covered by
Chapter 7 and Chapter 8, shall be permitted for installing
intrinsically safe apparatus.
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are you putting the IS barrier in the XP box?

504.10 Equipment Installation.
(A) Control Drawing. Intrinsically safe apparatus, associated
apparatus, and other equipment shall be installed in
accordance with the control drawing(s).
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most (maybe even all) of the "control drawings" I see show the barrier in a non-hazardous area.
 
Yes Sir, the barrier would be located in the XP box.
So it looks like any approved wiring method would be acceptable for an IS circuit.
 
kurt.brinker said:
Yes Sir, the barrier would be located in the XP box.
So it looks like any approved wiring method would be acceptable for an IS circuit.
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as long as the control drawing allows the barrier to be located in the XP box. you need to check the control drawing and see what it says.
 
I agree with Bob.

FWIW, I have seen control drawings which show the barrier in an XP box... but I don't recall if there were any other pertinent details, such as a physical barrier being required dependent on what else is in the box. Any way you go about it, I believe the control drawing showing the barrier in an XP box is required to proceed as such.
 
What aspect of an IS barrier's operation or protection would be affected by being installed in an XP box vs. in a non-hazardous area? I see that many control drawings call out 'non-hazardous' area installation, but I am wondering how barrier protection would be any different if in an XP box, provided all entity parameters were properly matched and grounding/wiring was correct. Pretty sure I have seem them installed in XP boxes, maybe incorrectly.

Is the inside of an XP box a hazardous location?
 
nhee2 said:
What aspect of an IS barrier's operation or protection would be affected by being installed in an XP box vs. in a non-hazardous area? I see that many control drawings call out 'non-hazardous' area installation, but I am wondering how barrier protection would be any different if in an XP box, provided all entity parameters were properly matched and grounding/wiring was correct. Pretty sure I have seem them installed in XP boxes, maybe incorrectly.
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See page Z-148 of this article:

http://www.omega.com/temperature/z/pdf/z131-148.pdf
 
Smart $ said:
See page Z-148 of this article:

http://www.omega.com/temperature/z/pdf/z131-148.pdf
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I don't understand what they are trying to show in the figure and I think the Figure is incorrect. They are showing an intrinsically safe seal (whatever that is) on a portion of the conduit that is not intrinsically safe. Assuming the application is Div 1, the seal between the boundary would need to be XP. I also don't understand the distinction the text is attempting to make - my opinion is all seals shown in the Figure should be XP. And it really doesn't speak to whether installing in an XP box invalidates the listing/control drawing.
 
nhee2 said:
I don't understand what they are trying to show in the figure and I think the Figure is incorrect. They are showing an intrinsically safe seal (whatever that is) on a portion of the conduit that is not intrinsically safe. Assuming the application is Div 1, the seal between the boundary would need to be XP. I also don't understand the distinction the text is attempting to make - my opinion is all seals shown in the Figure should be XP. And it really doesn't speak to whether installing in an XP box invalidates the listing/control drawing.
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The simplest explanation I can offer is this: neither the barrier not the input to the barrier are IS. To locate a barrier is inside a CID1 hazardous location, it must be within a XP enclosure and routing its input must use the same methods as non-IS hazardous location wiring... and the preceding should be supported with a control drawing.
 
Per 500.7(E) if wired intrinsically safe, which means you're also complying with the control drawing, article 501 (Class I locations) is N/A.

So to me right there would mean it does not matter what type of flex conduit you are using.
 
Kobe85 said:
Per 500.7(E) if wired intrinsically safe, which means you're also complying with the control drawing, article 501 (Class I locations) is N/A.

So to me right there would mean it does not matter what type of flex conduit you are using.
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And that's why you see most control drawings showing the barrier in the unclassified area. When you put an IS barrier within a CID1 hazardous area, the barrier and its input wiring are subject to CID1 wiring and protection methods. The IS circuit is only the output wiring and IS equipment connected thereto. The control drawing must show all of this in order to install the barrier inside the CID1 hazardous area.
 
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