Enclosure NEMA 4X Rating

[delectric123]

Is NEMA in charge of the design standards for NEMA enclosure ratings. One thing that I think should seriously be addressed, is that when enclosures are rated 4X they should be required to have stainless steel screws. In some corrosive atmospheres, brass screws are worse than steel screws. Logically one would think that a box rated for a corrosive atmosphere should be required to be made completely made of noncorrosive materials.


I have often come upon a junction box with the screws all rusted up. The only way to open it was either break the cover off or try luck with left-hand drill bits, or a vise grip plier. :rant:Then refastening sometimes requires creative ways. I dare say quite a few people would just leave the cover off. IMO, that's one way a lot of electrical hazards are created.:thumbsdown:


I know Carlon is very diligent with providing stainless steel screws, but I'm a big fan of other manufacturers as well, like Cantex and Kraloy. Kraloy can provide them on special order but who will go the more expensive route to win a bid?

Aren't others having similar problems?

 

[kwired]

What is suitable for a particular application really depends on what the corrosive agent is and what it reacts with. Stainless is great most of the time but I suppose there may be some things it doesn't play well with.

Looking at information on Wikipedia it looks like certain grades of stainless are better suited for different corrosive materials then others. Appears hydrochloric acid is corrosive to all kinds of stainless.

 

[delectric123]

My 4X environments are confined agricultural environments, usually with quite a bit of ammonia in the air. I've come upon 25 year old installations and the stainless screws were still in perfect condition. I've come so far as to have a bag of stainless #8 x 1/2 sheet metal screws on hand in new installations and not even use the steel screws provided. Technically that's going against the manufacturer's instructions as they require to use the screws provided but sometimes common sense prevails.


On the other hand I guess there possibly are extremely harsh environments where even stainless steel would be attacked. But it still would be a great improvement over nickel-plated steel, or brass.

 

[Jraef]

Technically, NEMA doesn't "control" anything, it's just a suggested specification guideline. But UL adopted the NEMA enclosure standards as UL 50 years ago, almost word for word. The difference was, NEMA was essentially a "self declaration" on the part of the manufacturers, with no accountability to anyone other than "the marketplace". UL on the other hand is a 3rd party TESTING lab, so to get the UL label, it must be tested and pass.

That said, the "X" in 4X is somewhat ambiguous and it is still up to the USER to ascertain what level of corrosives are in your environment. The UL/NEMA requirements are just that the enclosure must provide a DEGREE of protection against corrosion. Generally the test is a prolonged salt spay test as a minimum, but the manufactures are required to STATE the corrosive elements that a UL Type 4X enclosure is resistant to, then the USER compares that to what is a problem for them. One issue that also pops up is that some low-end suppliers will do the trick of UL listing their box as Type 1 or 12, then MARKETING it as "NEMA 4X", knowing that nobody will be challenging them on the NEMA claim as long as they don't say "UL Tyie 4X". It's an old trick but the major players know better than to try to pull it off.

SS is not a panacea and can do more harm than good in some chemical environments. But if YOU need SS hardware, YOU must take the added step of requiring it from your suppliers, understanding that it may result in an increased cost. I've had a couple of really nasty places where SS of any sort was not going to work, we had to go with Moly. Talk about expensive!

 

[kwired]

My 4X environments are confined agricultural environments, usually with quite a bit of ammonia in the air. I've come upon 25 year old installations and the stainless screws were still in perfect condition. I've come so far as to have a bag of stainless #8 x 1/2 sheet metal screws on hand in new installations and not even use the steel screws provided. Technically that's going against the manufacturer's instructions as they require to use the screws provided but sometimes common sense prevails.


On the other hand I guess there possibly are extremely harsh environments where even stainless steel would be attacked. But it still would be a great improvement over nickel-plated steel, or brass.

Ammonia is corrosive to brass.

 

[delectric123]

Ammonia is corrosive to brass.

Sorry, you misunderstood my statement. I dislike brass just as much as nickel-plated steel.

 

[delectric123]

SS is not a panacea and can do more harm than good in some chemical environments. But if YOU need SS hardware, YOU must take the added step of requiring it from your suppliers, understanding that it may result in an increased cost. I've had a couple of really nasty places where SS of any sort was not going to work, we had to go with Moly. Talk about expensive!

Isn't Moly a plastic? Plastic screws?

 

[mgookin]

Isn't Moly a plastic? Plastic screws?

I think he means molybdenum.

 

[kwired]

Sorry, you misunderstood my statement. I dislike brass just as much as nickel-plated steel.[/QUOT

I sort of mentioned that as a reply to both your OP and your later post where you mentioned issues with brass corroding in some of your installs.

I have encountered that as well in livestock buildings, it kind of gets forgotten about during installation but if you ever need to come back to fix or change something sometimes those brass screws are impossible to remove or the head may even be gone.