Seal off question

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rogue6144

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Can a seal off at an explosion proof switch in a Class1 Div1 area also serve as the boundary seal off if it is within 10 feet of the boundary to a non classified area? For instance a conduit passing through a wall into the non classified area?
 
rogue6144 said:
Can a seal off at an explosion proof switch in a Class1 Div1 area also serve as the boundary seal off if it is within 10 feet of the boundary to a non classified area? For instance a conduit passing through a wall into the non classified area?
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I would say yes, it appears to meet the requirements of 501.15(A)(4).
 
It is important to realize the 10' restriction applies to the length of conduit not the distance of the seal from the boundary. Otherwise I concur with the previous affirmative responses.
 
rbalex said:
It is important to realize the 10' restriction applies to the length of conduit not the distance of the seal from the boundary. Otherwise I concur with the previous affirmative responses.
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While I agree that to be the intent, the requirement is not worded that way... :p

(4) Class I, Division 1 Boundary. A conduit seal shall be
required in each conduit run leaving a Division 1 location.
The sealing fitting shall be permitted to be installed on
either side of the boundary within 3.05 m (10 ft) of the
boundary, and it shall be designed and installed to minimize
the amount of gas or vapor within the portion of the conduit
installed in the Division 1 location that can be communicated
beyond the seal. The conduit run between the conduit
seal and the point at which the conduit leaves the Division
1 location shall contain no union, coupling, box, or other
fitting except for a listed explosionproof reducer installed at
the conduit seal.

Exception No. 1: Metal conduit that contains no unions,
couplings, boxes, or fittings, that passes completely through
a Division 1 location with no fittings installed within
300 mm (12 in.) of either side of the boundary, shall not
require a conduit seal if the termination points of the unbroken
conduit are located in unclassified locations.

Exception No. 2: For underground conduit installed in
accordance with 300.5 where the boundary is below grade,
the sealing fitting shall be permitted to be installed after the
conduit emerges from below grade, but there shall be no
union, coupling, box, or fitting, other than listed explosionproof
reducers at the sealing fitting, in the conduit between
the sealing fitting and the point at which the conduit
emerges from below grade.
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It should be stated "...within the first 3.05 m (10 ft) of the conduit run from theboundary, ..."
 
Smart $ said:
...
It should be stated "...within the first 3.05 m (10 ft) of the conduit run from theboundary, ..."
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Well, it's pretty hard to comply otherwise with the "... shall contain no union, coupling, box, or other fitting ..." restriction with a standard stick of conduit. (I realize longer sticks can be purchased) The first sentence states we are discussing the conduit run.

I was the originator of the 10' limitation because previously there was no specific length and some inspectors were requiring a seal within 18" of the boundary. Subsequent wordsmithing got us where we are today. Make an IP if you choose. I'm pretty much out of the IP business.
 
rogue6144 said:
Can a seal off at an explosion proof switch in a Class1 Div1 area also serve as the boundary seal off if it is within 10 feet of the boundary to a non classified area? For instance a conduit passing through a wall into the non classified area?
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An explosion proof switch cannot act as a seal by itself, as I understand it.
 
dkidd said:
An explosion proof switch cannot act as a seal by itself, as I understand it.
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Yes, that's why the seal off goes upstream of the switch in the direction of the boundary.:roll: They may make them, but I've never seen a switch with an integrated seal off.
 
gadfly56 said:
Yes, that's why the seal off goes upstream of the switch in the direction of the boundary.:roll: They may make them, but I've never seen a switch with an integrated seal off.
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Seals go in all entries to the box and within 18" of the box, not just those entries that pass through the boundary.
 
Thanks for the input. The seal off would be less than 18" from the switch on the conduit passing through the wall. Also, there would be no fittings between the seal off and the wall and the conduit would be less than 10'. I think it would be permissible to use that seal off for the boundary too.
 
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