NEMA 4 means a fire hose in a dust hurricane is not going to get into your enclosure if you maintain NEMA 4 integrity.

NEMA 4X "additional level" means only that a NEMA 4 enclosure is made out of something that cannot corrode, often it means the enclosure is made out of fiberglass or polycarbonate instead of painted steel.

Keith Cress
kcress - http://www.flaminsystems.com

NEMA 4X can also imply a stainless-steel panel, in addition to fiber-glass or poly-carb type.

Thank both you for your responses. I just now realized that the original posting includes a typo that I must correct.

1. The original text says, "...provides an additional level of protection against construction..."?
2. whereas it should have said, "...provides an additional level of protection against CORROSION..."?

I qualitatively understand that NEMA is suggesting that NEMA 4X rated panels are generally water tight. I gather that they must be qualitatively implying that NEMA 4X panels are also relatively gas tight (i.e., apart from any air movement that occurs in the conduits that interconnect with the panels).

More specifically, my question pertains to whether or not NEMA has any quantitative definitions for how water tight and how gas tight an enclosure needs to be in order to carry the NEMA 4X rating? In other words, is there a standard set of defined tests that NEMA panels are subject to in order to meet the stated NEMA rating classification? I would be grateful for any information related to this subject matter.

Thank you!

Absolutely there are specific defined tests. But for a feel of them you should just look at any user description of the various Enclosure protection levels. I remember looking at that in Hoffman catalogs a couple of times. As I recall NEMA12 was like wind and vertical water failing down. etc etc.

Keith Cress
kcress - http://www.flaminsystems.com

For NEMA panel designations, refer to;

https://www.nema.org/Products/Documents/nema-enclo...

GroovyGuy: Thanks for the link to the NEMA.org NEMA enclosure types definitions. I am grateful although I have to admit that I have previously referenced that same document in the past and always wondered what NEMA specifically means by "...offers and additional level of protection against corrosion, etc....". The NEMA.org definitions seem to be on the generic side.

I think that, per itsmoked's suggestion, I will take a look through the Hoffman catalogues to see if they either have specific testing quantitative criteria or if they reference an industry testing standard that the NEMA ratings must comply with in order to satisfy the NEMA.org published generic definitions.

Thank you both again!

hondashadow1100vt,

I recall reading somewhere that the test for NEMA4 is a 1" hose at 64gpm for half an hour. I have also been told that a fire hose is quite a bit more powerful than this.

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JHG