Seal-Off Requirement

[baumancl]

If anyone can give some insite to the following query.

If there is a conduit routed from a Class 1, Div. I location in which the boundry is below grade from my interpretation of article 501.15 there is an exception to allow the seal-off to be located when the conduit emerges from below grade.

Here is the set up. I have seen a design where a conduit is routed from a Class 1, Div. I location (wet well with submersible pumps) in which the boundry is below grade. The conduit emerged from below grade at an outdoor panel support structure and stops a couple inches above finished grade and is secured to the back of the support structure. Then there is an open air gap for about 18" and then the conduit starts again and terminates into an enclosure. To protect the cables being routed in the conduit at the open air portion there is a stainless steel screen mesh which overlapps the conduit emerging from below grade and the conduit that continues to the panel.

Does this meet code? I am assuming that the open air protion is serving as a form of a ventilated bussway but I can only find that this is acceptable in an exception for Class 1, Div. 2 locations in article 501.15. Is it a coincidence that the gap is about 18" and it starts right after the conduit emerges from below grade or does this maybe apply to the fact that for 18" after the boundry it might be considered a Class 1, Div. 2 location and indeed they are considering the mesh screen a ventilated bussway?

Anyone who can at least shed light if this installation is code compliant or not would be helpful.

 

[Rockyd]

Are the cables MC-HL or CLX (need to be rated for the environment) ? Cables have TMCX connectors that work for classified spaces. Where I normally work in classified space, the first fitting above grade is the seal-off, followed by having all pipes entering a box, fit a UNY going into the can. The union allows you to get the box out, if you ever had to do a major rework.

 

[rbalex]

The first thing to consider is if the underground is truly Division 1. It isn’t typically but a few Articles and Standards may define or treat it that way. Assuming it is properly classified as Division 1, then basically all you have to know is in Section 501.15 (A)(4).

Exceptions don’t necessarily address the entire main rule; they may only alter part of it. In the case of 501.15 (A)(4), Ex 2, it simply recognizes that a seal must be accessible [501.15 (C)(1)] so it is permitted to be at the point where it leaves the ground. The rest of the main rule is left intact.

As I understand your description of it so far, the installation is a violation.