UL 508A Supplement SA 1.1 Exception No.2

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SMP_PRO

Member
Location
Michigan
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Safety Engineer
There is a line in the Supplement SA for UL 508A panels, "1.1 Exception No. 2 c)".

Exception No. 2: The following hazardous locations equipment and associated apparatus shall not be used as part of an ordinary locations industrial control panel:
a) An explosion-proof enclosure marked for Class I hazardous locations (or Type 7).
b) A dust-ignition-proof enclosure marked for Class II hazardous locations (or Type 9),
c) A barrier or other equipment that provides intrinsically safe input/output connections for use in Class I, II, and III hazardous locations
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I am working on a design for a panel in an ordinary location where the customer specified a Rockwell IO board that is listed under a hazardous location standard.

Class I, Division 2, Group A, B, C and D

The part number in question is 1492-AIFM8-F-5.

This section of the standard makes it clear to me a component listed for a hazardous location with intrinsically safe input/output connections like an IO field wiring board can't be used in an oridinary panel. I'm struggling to fine the reasoning for this, or if I'm misunderstanding this section of the supplement. Has anyone run across this before on a UL 508A panel?
 
SMP_PRO said:
There is a line in the Supplement SA for UL 508A panels, "1.1 Exception No. 2 c)".



I am working on a design for a panel in an ordinary location where the customer specified a Rockwell IO board that is listed under a hazardous location standard.

Class I, Division 2, Group A, B, C and D

The part number in question is 1492-AIFM8-F-5.

This section of the standard makes it clear to me a component listed for a hazardous location with intrinsically safe input/output connections like an IO field wiring board can't be used in an oridinary panel. I'm struggling to fine the reasoning for this, or if I'm misunderstanding this section of the supplement. Has anyone run across this before on a UL 508A panel?
Click to expand...
QUOTE from 508A Supplement A: "A barrier or other equipment that provides intrinsically safe input/output connections for use in Class I, II, and III hazardous locations"

I read this statement as saying that you can't use the part to provide connections to a hazardous location, since your panel would be listed for 508A, which is not the correct standard for a hazardous location panel. If you want to use the part in a 508A panel, you just can't connect it to anything in a hazardous location. Corollary: I can use a Type 4 enclosure indoors in a dry location if I want to; I can't use a Type 1 location panel in a wet location.

If the Rockwell IO board ONLY has a listing for HAZLOC (I'd be very surprised), it might be an issue. You'd have to ask your UL inspector - the part might just be needed to be added to your shop's procedure. Warning: your mileage may vary. I had very hit-or-miss experiences with UL when interacting with them while we were a 508A panel shop. We had a different inspector every time, and none of them were actually subject matter experts in control panels - one guy did fire doors. Getting them to answer even simple questions was like trying to nail jello to the ceiling on a warm day.


SceneryDriver
 
I appreciate the feedback! I can read the statement differently as you pointed out and it makes more logical sense to me. Panels in hazardous locations are very much out of the scope of 508A, so I can understand why UL might have to make this distinction in their standards. If you're making a connection to a hazardous location you need to follow the standard concerning that location.

Getting an email back regarding this has been exactly as you said, nailing jello to the ceiling on a warm day.
 
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