Wiring in hazardous location - NEC Std. - On-Skid of Moto-Compressor

[JuanBC]

Hello,

I would like your comments regarding the attached picture (Instrumentation cables wired on-skid of a gas compressor - Location classified as Class I Div. II Gr. 'D' T1)

Is it enough to only use a "sealer"? (At both ends) -- Cables used inside conduit are NOT armoured

I am not familiar with NEC wiring, we usually wire everything under IEC standard (Armoured cable wired through open conduits with fittings for hazzardous locations at both ends)

I really appreciate your help. Regards,

JBC
.......
"The more I read, the more I acquire, the more certain I am that I know nothing"

 

[FreddyNurk]

As zdas01 and others can tell you, there's a huge difference in what is acceptable between IEC standards and NEC standards. I've only seen IEC standards, but from what I can gather the methods are so divergent that what is accepted in one jurisdiction is banned in the other.

Others with direct experience in NEC requirements will be able to advise you.

EDMS Australia

 

[DRWeig]

In general, things that do not arc or spark or get really hot during normal operation can be used in Div 2 locations in general-purpose enclosures. You have switches and stuff that DO arc or spark, so they had to use a Class I Div 1 enclosure. As for cabling, it's only required to be sealed at the point of entry into a Class I Div 1 enclosure (like the explosion proof control panel in your picture). The purpose of cable sealing is to keep hazardous gases from leaving the Div 1 location and creating a hazard in the Div 2 location.

Wiring methods, like your conduit body and flexible conduit are fine in Div 2 locations, again as long as there's a good seal at the point of entry into the Div 1 area. If you're nervous, seal the other end too -- it doesn't cost much, but it's not required.

Hope this helps. Also, wait for other responses to see if they agree with me.

Best to you,

Goober Dave

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[dup18]

The engine block heater in the picture is required to be explosion proof (Class I, Div 1)because the box contains circuit breakers and line starters (contactors) that arc and spark normally. As such, there must be an explosion proof seal(s) within 18 inches of the enclosure, per Chapter 5 of the National Electrical Code in the U.S. The key phrase is "required to be explosion-proof".
Podo

 

[JuanBC]

Hi Dave & Podo.

Thanks for your answers

I understand that the enclosure must be explosion-proof and that a seal is a requeriment (article 501.15) but I also think that it is also required that the installation comply with article 501.10(B) [Wiring method to be used in a zone classified as Class I Division 2]

I still think that the installation does not look like any of the options recommended by 501.10 (B)

Thanks,

JBC
.......
"The more I read, the more I acquire, the more certain I am that I know nothing"

 

[podobing]

From the picture, it is hard to tell if they are explosion proof seals just below the block heater starter box. They look small. If they are explosion proof, then the remainder of the conduit fittings are in a Class I, Division 2 environment. You will need another seal off fitting within 10 feet of the boundary between the CID2 area and the unclassified area, with no other fittings between the seal off and the boundary (except X/P unions).

 

[JuanBC]

Podo,

The sealers are Explosion-Proof (and there are other sealers at the boundary) but the conduit fittings used (conduit outlet bodies, covers, gaskets, nipples, couplings, and flexible tubes) are not listed

JBC
.......
"The more I read, the more I acquire, the more certain I am that I know nothing"