IS Intrument Ratings

[bs123]

In regards installing IS instruments in Class II, Div 1, Group F classified areas.

We have correctly paired barriers and inductive proximity sensors.
The Barrier is UL approved for CLII, Div 1, Gp F areas, however the switch is IECEx approved for dust (II 1D Ex IIC T6).

Is this acceptable under under the NEC? or does the switch also need to be rated to the NEC standard?

Thanks in advance.

 

[rbalex]

If the NEC the actual installation standard, IEC ratings and markings are meaningless even for NEC Zones. The barrier is fine; the switch would be questionable.

I forgot to add: "Do you have a control drawing for the IS installation?"

 

[petersonra]

If the NEC the actual installation standard, IEC ratings and markings are meaningless even for NEC Zones. The barrier is fine; the switch would be questionable.

I think the switch itself might be OK but I don't see how you can claim the switch enclosure is dust tight to NEC standards when it is only IEC dust tight. I know that seems trivial and it probably is, but you are probably going to have to get some dispensation from the AHj on this one. Why not just use a US style switch since you are using the NEC?

502.115
(A) Class II, Division 1. In Class II, Division 1 locations,
switches, circuit breakers, motor controllers, fuses, push
buttons, relays, and similar devices shall be provided with
enclosures identified for the location.

I don't see how your switch enclosure is identified for this location.

 

[rbalex]

I think the switch itself might be OK but I don't see how you can claim the switch enclosure is dust tight to NEC standards when it is only IEC dust tight. I know that seems trivial and it probably is, but you are probably going to have to get some dispensation from the AHj on this one. Why not just use a US style switch since you are using the NEC?



I don't see how your switch enclosure is identified for this location.

An IS installation wouldn't need to be dusttight.

 

[petersonra]

An IS installation wouldn't need to be dusttight.

It does say that now that I took a closer look at 504.

It also says this

504.4 Equipment. All intrinsically safe apparatus and associated
apparatus shall be listed.
Exception: Simple apparatus, as described on the control
drawing, shall not be required to be listed.

Switches are pretty much the epitome of "simple devices". The enclosure would also appear to be a "simple device".

So what would be the issue of using this switch in an IS circuit in this case? Would that be because the enclosure might not specified on the control drawing?

 

[bs123]

IS Intrument Ratings

Thanks all for the feedback.

The real issue is the idea of using IECEx equipment in NEC classified areas. Alot of equipment supplied is Ex, not NEC.
I was hoping that because it is in an IS circuit it would negate the requirement for rated equipment on the IS side of the barrier.

I've used unclassified instruments inside classified areas before (under IEC) by making the circuit IS.
Is this the same for the NEC?

We do have a control drawing based on the IS requirements of the paired barrier and switch.

Thanks.

 

[rbalex]

Thanks all for the feedback.

The real issue is the idea of using IECEx equipment in NEC classified areas...

Yes, it's the real issue - and it's a big one even for IS installations.

Equipment, only marked per IEC, is not generally acceptable under the NEC.

There is a provision in Section 502.6 that permits NEC Zone rated equipment in Class II, Division classified locations. However once you wind your way through all the cross-references, you will find that the equipment must be marked "AEx". That means it has been certified by a Nationally Recognized Testing Laboratory (NRTL). A simple "Ex", even ATEX certified, is not acceptable.

Installed under an appropriate control drawing may be acceptable.

 

[rbalex]

A note of caution: If the installation is within the jurisdiction of US Federal OSHA or MSHA, if you can use a listed switch, you must. This could also be a requirement of the local jurisdiction. (I have no idea what Panama requires; that's why I couldn't help with your other question.)

 

[bs123]

A note of caution: If the installation is within the jurisdiction of US Federal OSHA or MSHA, if you can use a listed switch, you must. This could also be a requirement of the local jurisdiction. (I have no idea what Panama requires; that's why I couldn't help with your other question.)

Thanks. better to be safe than sorry. I don't think anyone knows what panama requires.