SEAL OFFS IN CLASS I . div 1 location

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SIRKIT

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This is a sewer plant .Just where do we need to place seal offs. The engineer wants them at each piece of equipment. Plus just before we go thru the wall??
 

Dennis Alwon

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Chapel Hill, NC
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Retired Electrical Contractor
This is a sewer plant .Just where do we need to place seal offs. The engineer wants them at each piece of equipment. Plus just before we go thru the wall??

If the engineer calls for seal offs then you must supply them whether the NEC requires it or not.

Hopefully someone can chime in on this who knows where they are required.
 

marti smith

Senior Member
My thoughts are (and if incorrect it will be swiftly and duly noted) that unless the wall is part of the cavity or enclosure as stated below, then no, unless as Dennis said, it is spec'd that way.


514.9 Sealing.

(A) At Dispenser. A listed seal shall be provided in each conduit run entering or leaving a dispenser or any cavities or enclosures in direct communication therewith. The sealing fitting shall be the first fitting after the conduit emerges from the earth or concrete
 

don_resqcapt19

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Illinois
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retired electrician
Have the engineer show you the electrical classification documents. They will show the Class and Division. That information really determines where the seals are required as well as what wiring methods are permitted. There is more to wiring classified areas than just seals.

However, as Dennis said, if the engineer specifies seals, even in areas where the NEC does not require them, you have to provide them.
 

don_resqcapt19

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Illinois
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retired electrician
Marti,
Article 514 only applies to Motor Fuel Dispensing Facilities. Nothing in that article would apply to a sewer plant. You would look to Article 501 for the rules that apply to a sewer plant, but you would still need the area classification documents to be able to apply the rules in Article 501.
 

Smart $

Esteemed Member
Location
Ohio
This is a sewer plant .Just where do we need to place seal offs. The engineer wants them at each piece of equipment. Plus just before we go thru the wall??
If the wall is the Class I Division 1 boundary, and the conduit run extends beyond the boundary, then under the NEC a seal off is required within 10 ft either side with no fittings between boundary and seal off except for XP reducers in the seal off hub.

Generically requiring seal offs at each piece of equipment is not unreasonable (eliminates uncertainty) unless enclosures are pressurized (i.e. utilize purging system).
 
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