Class 1 Division 1 Purged / Pressurized Enclosures in Series

[prosys]

I have multiple enclosures in series with one purge unit in a class 1 division 1 area. My question is this, can I connect the enclosures to each other with Type EF Liquid Tight? The liquid tight serves as my raceway and air path, plus I need the flexibility of the liquid tight. NFPA 496 does not state clearly the requirements for connecting purged enclosure in series. Can somebody over some advice on this subject??

 

[rbalex]

Assuming you meet all the other rigorous requirements of a Type X pressurized system, you may indeed use LFMC as both raceway and airway.

I personally prefer to pipe each enclosure separately, but that is a design choice, not a requirement.

 

[prosys]

Thank you for your response. Your assumptions are correct about the type X purge system. Is there a particular spot in the NEC or NFPA that states Type EF liquid tight is acceptable? I have a customer that will require me to quote text from one of the code books.

 

[rbalex]

Fundamentally, you start with NEC Section 500.7 (D). Note, unlike some of the other Protection Techniques, it has virtually no general restrictions in application.

Philosophically and functionally, see Section 501.15(A)(2) where the NEC recognizes seals aren?t needed with pressurized enclosures in Division 1.

 

[LightMyFire]

Junction Boxes

Junction Boxes

One aspect of the NEC 500 I never quite understood is the level of protection certain fixtures like hazardous location emergency lights require, yet you can use a typical non-airtight junction box to wire them? Isn't there still an explosion danger posed by these unprotected j-boxes?

Aaron

 

[rbalex]

One aspect of the NEC 500 I never quite understood is the level of protection certain fixtures like hazardous location emergency lights require, yet you can use a typical non-airtight junction box to wire them? Isn't there still an explosion danger posed by these unprotected j-boxes?

Aaron

What is the area classification you are referencing?