NEMA 4X-7, is group A required?

[Hugo G]

Hello eng-tips,

TOday i come with a small question regarding enclosure certifications:

As far as I understand, NEMA 4X+7 is a denomination given for non-hazardous outdoor area (4X) and hazardous indoor Class I, Division 1, Groups A, B, C, or D (7)

What isn't clear for me are the groups requirements for type 7: in order to achieve type 7 certification, shall the equipment be approved to groups A, B, C and D or could it be a combination of these, BCD for example?

In this particular escenario, I have a FM certification as follows:

XP / I / 1 / BCD / T4
DIP / II / 1 / EFG / T4; Type 3, 4, 4X, 6, IP66, IP68

As i understand it, this equipment is approved as explosion proof for Class I, Division 1, Groups B, C and D, also a Dust-Ignitionproof certification for Class II, Division 1, groups EFG. As well as enclosure Type 3,4,4X and 6.

The 4X part is pretty clear, however, as for type 7, FM doesn't mention it in the provided approval guide. Could this equipment be classified as Nema 4X+7 considering it has XP certification for Class I, Division 1, Groups BCD?

The equipment we're talking about is an electric actuator, the fluid is LPG which is classified as group D by NEC.

Thank you in advance and please forgive any grammar mistake as english isn't my mother language.

 

[xnuke]

I think you should get that interpretation directly from FM and keep a copy of their response in your project files rather than get opinions here. That kind of documentation could be required for insurance purposes later.

xnuke
"Live and act within the limit of your knowledge and keep expanding it to the limit of your life." Ayn Rand, Atlas Shrugged.
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[jraef]

I'm not sure where you are coming from here.

NEMA 7 is not a testing authority, it is a set of industry design standards that helps people pick out products more quickly. FM and UL are testing and listing agencies. So if you have an environment that needs Class 1 Div. 1 Groups B, C and D requirements, a NEMA 7 enclosed product would work, but may STILL need additional listings from an agency like FM or UL.

On the other hand if you have a device that says it is FM listed for Cl 1, Div. 1 Gps B, C and D, but does not state that it meets NEMA 7, then it would not be "NEMA 7". However, that NEMA rating is typically not an acceptable certification when it comes to installation requirements anyway, so it's basically irrelevant. If you are reading a specification that simply calls for NEMA 7 and 4X, but does not require NRTL listing, then whomever wrote that spec is being lazy and covering their bases. If your ENVIRONMENT does not need Group A (acetylene), then it doesn't need Group A.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[Hugo G]

Thanks a lot for your answers,

I'm asking just to have a better understanding of this matter in order the ask the correct questions to the user and to the equipment's manufacturer.

The spec just calls for Enclosure protection as NEMA 4X+7 hence my confusion, I will ask for a more clear requirement from the user.

 

[jraef]

That's the best course of action here. I find that often times, people spew out requirements without much thought to it and when questioned, you are forcing them to do the proper thinking.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden