Transition from Cl1, Div2 to Outside

[jgrassel]

Could someone help me understand if seals are needed!? I was planning to use them to go from a classified area to a non-hazardous area, but now there will be an transition to outside, where I will have a gap between buildings, essentially. Does that allow me to save money on seals and such by terminating the conduit at the wall, then use an outdoor rated cable from that point into the next building, a few feet away, which is classified non-hazardous?

Thanks for the help!

 

[rbalex]

Without knowing the scope of the installation, I'm always a bit leery when someone I'm not familiar with describes an indoor Class I location as only Division 2. They certainly can be and my response assumes that the classification was determined by someone qualified to do so.

See Section 501.15(B)(2) Ex 2.

BTW, with respect to Articles 500 through 516, the term "nonhazardous" does not exist. The proper term is unclassified. See Section 500.2.

 

[jgrassel]

Thank you for the information. I appreciate the help.

Thank you for the information. I appreciate the help.

.

 

[petersonra]

See Section 501.15(B)(2) Ex 2.

What is the thinking here? wouldn't you want to prevent the transmission of hazardous gases through the conduit into the unclassified area just as much if it was rigid as if it is a cable or cord of some sort?

 

[rbalex]

What is the thinking here? wouldn't you want to prevent the transmission of hazardous gases through the conduit into the unclassified area just as much if it was rigid as if it is a cable or cord of some sort?

What hazardous gases? The "source" is Division 2; there aren't supposed to be any gases or vapors in the first place.

As for cables and cords see Section 501.15(E); especially Subsection 501.15(E)(3). That is, even cables with a gas/vaportight continuous sheath capable of transmitting gases or vapors through the cable core shall not be required to be sealed unless:

1. They are terminated in an enclosure that is required to be explosionproof [Section 501.15(E)(1)] OR
2. They are attached to process equipment or devices that may cause a pressure in excess of 1500 pascals (6 in. of water) to be exerted at a cable end.

BTW "... 1500 pascals (6 in. of water)..." is the standard for explosionproof seals [See 501.15(E)(2)]; i.e., they are neither water or gas/vapor proof. I will be proposing this be specifically documented in 501.15(C) and referred to by reference in 501.15(E)(2) and (3).

 

[petersonra]

What hazardous gases? The "source" is Division 2; there aren't supposed to be any gases or vapors in the first place.

As for cables and cords see Section 501.15(E); especially Subsection 501.15(E)(3). That is, even cables with a gas/vaportight continuous sheath capable of transmitting gases or vapors through the cable core shall not be required to be sealed unless:

1. They are terminated in an enclosure that is required to be explosionproof [Section 501.15(E)(1)] OR
2. They are attached to process equipment or devices that may cause a pressure in excess of 1500 pascals (6 in. of water) to be exerted at a cable end.

BTW "... 1500 pascals (6 in. of water)..." is the standard for explosionproof seals [See 501.15(E)(2)]; i.e., they are neither water or gas/vapor proof. I will be proposing this be specifically documented in 501.15(C) and referred to by reference in 501.15(E)(2) and (3).

So why is any sealing ever required between a D2 and an unclassified area?

 

[rbalex]

So why is any sealing ever required between a D2 and an unclassified area?

Good question - I submitted just such a Proposal when the CMP decided explosionproof seals weren't required between Division 2/unclassified locations. I can only say what the Code says, I can't necessarily explain why it says it.

Actually, there are a few cases where I believe such seals are still warranted; usually where there is a significant pressure differential across the boundary AND a means to "collect" the gases/vapors in the unclassified location over time. Aboveground to underground at grade would be an example. Where a heavily mechanically ventilated indoor Division 2 location fed an unventilated enclosure in an unclassified location would be another.