Sealing conduit run underground from Class 1 location

[greenspark1]

Hi all,
I have a large number of conduits coming from equipment in a Class 1 & 2 location (24" below grade) into a building located in an non-hazardous location. The conduits are all sealed before they go underground. When they come out of ground in the building, do they all need to be sealed again before entering any panels/etc? This seems redundant. Also, are there any smaller seals than the EYS I'm used to using?
http://www.cooperindustries.com/con.../conduit-unions/conduit_sealing_fittings.html
It's tough to fit seals on these risers before entering panels and especially freestanding equipment. Thanks a ton!

 

[rbalex]

Unless you are dealing with Articles 511 to 516 where the classification/installation rules are specific, the answer lies with how you classified below grade.

 

[kwired]

Hi all,
I have a large number of conduits coming from equipment in a Class 1 & 2 location (24" below grade) into a building located in an non-hazardous location. The conduits are all sealed before they go underground. When they come out of ground in the building, do they all need to be sealed again before entering any panels/etc? This seems redundant. Also, are there any smaller seals than the EYS I'm used to using?
http://www.cooperindustries.com/con.../conduit-unions/conduit_sealing_fittings.html
It's tough to fit seals on these risers before entering panels and especially freestanding equipment. Thanks a ton!

Size of sealing fitting is the way it is because of the space needed to make a proper seal. sometimes this even means using a larger seal fitting then the raceway it is attached to because of conductor fill. Normal raceway fill is 40% for over 2 conductors, but (off the top of my head) I think you can only fill a sealing fitting to 25% in order to get a proper seal.

Then of course like Bob mentioned - exactly where boundaries are located and what the underground classification may be can make a difference as to whether you need the seal at the far end.

At gas stations it is often difficult to get all the raceways into the equipment it needs to go to and most often those raceways enter an aux gutter where it is easier to allow needed spacing - then they run from the aux gutter to the equipment.

 

[rbalex]

Some time ago I wrote a mini-treatise about maximum seal fitting fill. There are other factors that can affect the physical size though, such as minimum thickness of the sealing compound. See Section 501.15(C). That said, a slightly more compact format is "right next door" on greenspark1's link. I have often specified sealing hubs for "at grade" boundary seals that terminate in a terminal box.

Except for Articles 511 to 516, below grade is usually considered unclassified. That eliminates underground "boundaries" and the hassle of determining where to place a seal within 10 feet of the boundary.