Assume that a single conduit stubs up on each side of an explosion proof boundry. One side is class 1, div 1, and the other side is unclassified. Which side must the EYS seal off be placed at? Does the NEC require a seal off on both sides?
I'm just a broke down old engineer trying to get a proper exp proof system installed here in the middle east on a jet fuel system for a USAF base. Your answer seemed alittle brief. I believe I understand "either side" and a referal to an NEC article. Please provide an answer with a couple more words.
Thanks, W. N. Beaty, P.E., US citizen, somewhere in the Arabian desert.
That's pretty good. That's what I was thinking but I didn't have a code reference in mind. Since you had the best answer, I'll provide the blah, blah, blah:
501.15 Sealing and Drainage 4) Class I, Division 1 Boundary
In each conduit run leaving a Class I, Division 1 location. The sealing fitting shall be permitted on either side of the boundary of such location within 3.05 m (10 ft) of the boundary and shall be designed and installed so as to minimize the amount of gas or vapor within the Division 1 portion of the conduit from being communicated to the conduit beyond the seal. Except for listed explosionproof reducers at the conduit seal, there shall be no union, coupling, box, or fitting between the conduit seal and the point at which the conduit leaves the Division 1 location.
Exception No. 1: Metal conduit that contains no unions, couplings, boxes, or fittings, and passes completely through a Class I, Division 1 location with no fittings less than 300 mm (12 in.) beyond each boundary, shall not require a conduit seal if the termination points of the unbroken conduit are in unclassified locations.
Exception No. 2: For underground conduit installed in accordance with 300.5 where the boundary is beneath the ground, the sealing fitting shall be permitted to be installed after the conduit leaves the ground, 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 leaves the ground.
There is more to this article of coarse but this is the part that answers your question. Me personally, I like using Cooper Crouse-Hinds Code digest which has pictures , part numbers and code language all in one place. I know you don't have a "local" Crouse-Hinds dealer (or maybe you do) but you'll have to get the parts from somewhere. They would be happy to give you one of these.
Best of luck and stay safe out there. I know YOU are risking your life to!
The OP description of the installation is confusing me a bit.
Without some physical barrier there MUST also be a Division 2 ”buffer” between the Division 1 location and the unclassified location.
If there is some physical barrier, such as a wall, between then Division I location and the unclassified location, and assuming it is less than 10’ thick, then the seal may be on either side, but not more than 10’ from the Division 1 face.
Another possible case: “Stub-up” generally implies a vertical penetration at grade. In that case the raceway run penetrates grade in the Division I location, runs some indefinite distance underground and then exits at grade in an unclassified location. In this case, the seal must, for practical reasons, be in the Division 1 side since 501.15(C)(1) also requires it to be accessible.(Edit Add: It can't be within 10' but underground.)
In either case, a single seal is all that is necessary except in some limited applications in Articles 511 to 516. I can’t tell from the OP if any apply.