NEMA 7X 1

[NL8]

Can anybody tell me the exact definition of a NEMA 7X enclosure. Our best guess here, backed by some research, is a ENMA 7 enclosure that meets all the requirements of a NEMA 4X enclosure as well.

Joe Hasik, CSWP
SW 08 x64, SP 3.0
Dell T3400
Intel Core2 Quad
Q6700 2.66 GHz
3.93 GB RAM
NVIDIA Quadro FX 4600

 

[itsmoked]

I suspect that is wrong.

I have never heard of a NEMA 7 anything, let alone 7X.

I believe X means non metallic enclosure, think fiberglass. Hence non-corrodible.

But '7' makes no sense to me.

Looking at Hoffman's,(largest maker of enclosures), technical references shows nothing of "7".

After all once you've described about every possibility already, why would you need another? How many shades of black are there? If you get my point.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[resqcapt19]

Keith,
The "X" is used for corrosion resistance, not non-metallic, for example a NEMA 4X can be stainless steel or some non-metallic material. NEMA 7 is an enclosure for NEC Class 1 areas and is of the explosionproof type. I don't think that Hoffman makes that type of enclosure.
I have never heard of a 7X either. I do know that if you have an enclosure that is rated only NEMA 7 it is not suitable for wet locations. A wet location explosionproof enclosure has to have a NEMA 3R or 4 rating in additon to the NEMA 7 rating.

 

[itsmoked]

Thanks resqcapt19!

I learn something everyday.

Shame on Hoffman for apparently carving out of the NEMA standards any type they don't provide..

Keith Cress
kcress -

http://www.flaminsystems.com

 

[roydm]

NEMA 7 is the explosion proof rating for Class 1 Div 1 Group A,B,C,D (indoors), we spec that for some of our plants.
7X is corrosion resistant version as Keith said.
Regards
Roy

 

[resqcapt19]

Roy,
Is that an official NEMA type or just something that a manufacturer is using? I don't find it in this NEMA document.

 

[dpc]

resqcapt19,

The list you reference is only for nonhazardous locations.

NEMA 7 is an official NEMA type for explosion-proof enclosures. I don't recall ever seeing a NEMA 7X enclosure.

http://www.cdynamics.com/nema-4.html

 

[roydm]

Resqcapt19, Dpc,
Your'e both right, I couldn't find the X either. I was using a vendors chart.
Sorry about that.
I will print out the useful links and use that in future.
Roy

 

[NL8]

Thanks everybody for covering the bases, it sounds like my manufacturer is just being cute with a NEMA standard.

Joe Hasik, CSWP
SW 08 x64, SP 3.0
Dell T3400
Intel Core2 Quad
Q6700 2.66 GHz
3.93 GB RAM
NVIDIA Quadro FX 4600

 

[dpc]

There are specific NEMA requirements for corrosion resistance, so I guess it's possible an enclosure could qualify as a NEMA 7 and corrosion-resistant.

Because of the nature of NEMA 7 enclosures, it is difficult to have an enclosure that is NEMA 7 AND NEMA 4.

 

[resqcapt19]

dpc,
About the middle of page five of the document I linked to talks about hazardous area enclosures...even talks about an NEMA 8 (oil filled) that I don't think I have ever heard of before.
The biggest point that I want to make is the fact that enclosures that have only 7 or 9 ratings are not suitable for outdoor or other wet locations. For that type of application the enclosure must have an additional rating like 3R or 4. It seems that a number of installers have assumed that if the enclosure is explosionproof (NEMA 7) that it is automatically weatherproof and that is not the case.
Don