Wetwell pullbox

[QES]

I have a pump cable leaving a stormwater wetwell(class 1 div 2) and into a pullbox 1 foot away. The pullbox is to splice the pump cable with the cable going into a control room( 50ft away from pullbox).
Do you require to use conduits seal?

 

[augie47]

I do. 501.15(B)(2). I believe

 

[QES]

is splicing permitted in a class 1 div 2 area?

 

[weressl]

is splicing permitted in a class 1 div 2 area?

Yes.

I am somewhat surprised though that a wetwell is Division 2. I would expect it to be Div. 1 unless there are measures taken to continually maintain fresh air supply to keep it above LEL and only upon failure of the air supply do you expect to have an ignitable mixture.

 

[QES]

based on nfpa 820 a stormwater wetwell is class 1 div2.

 

[rbalex]

NFPA 820 is the proper Standard. It recognizes the amount of methane generated is dissipated quickly and it only takes a very mild air movement to dilute it sufficiently. The H2S we typically smell is already well below the LEL.

 

[weressl]

NFPA 820 is the proper Standard. It recognizes the amount of methane generated is dissipated quickly and it only takes a very mild air movement to dilute it sufficiently. The H2S we typically smell is already well below the LEL.

Sorry, my chemical plant mindset just seems to dominant in my experience. Our stormwater wetwells need to be assumed to be also chemical spill wapor collection areas.

I understand that 820 may be the correct standard in other applications. Hydrogensulfide is one thing, but I wonder though that the methane released from organic decay is taken into consideration.

 

[rbalex]

Everyone’s experience dominates their own mindset. :grin: I’m certainly not immune; that’s why I often wait a few hours (sometimes a day) to reply because I need to review my own “mindset” for proper application.

Fortunately, NFPA provides access to all their documents. NFPA 820-2003 and 2008 are available online.

I reviewed Chapters 5, 6 and 7 and especially the Tables associated with “Design and Construction.” I also reviewed ventilation requirements in Chapter 9 and a bit of the “Explanatory” material in Annexes A and B before I responded. The Formal Interpretation at the end of the document is also relevant. (Page 66 - right after the Index in the 2008 Edition)

While ventilation is not ignored, it appears the collective experience of the NFPA 820 Technical Committee is that Division 1 usually requires a totally unventilated enclosed area.

I was already aware (my “mindset” from my work on the API Subcommittee on Electrical Equipment) that methane dissipates very quickly in open air.

Edit: Added the FI reference page.details