501.15 (B)(2)

500.15 (b) (2) [Editor note: Actually 501.15(B)(2)]

I am curious it states I must have a seal off with in 10 feet of the boundry line on either side of the boundry line. Could some one clarify what they mean by either side of the boundry line.

If I have RMC ran from the waste water wet well to a control box and the point it leaves the ground is furth then 10 ft then where do I put the seal off. I was told it needs to be installed with in 18 inches of the point it comes up out of the ground. I can not find this in the code could some one point me in the right direction.
 
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Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Electrician
500.15 (b) (2)

I am curious it states I must have a seal off with in 10 feet of the boundry line on either side of the boundry line. Could some one clarify what they mean by either side of the boundry line.

I believe this means exactly what it says, you can put the seal on either side of the determined boundary as long as it is within 10' of the boundary.


If I have RMC ran from the waste water wet well to a control box and the point it leaves the ground is furth then 10 ft then where do I put the seal off. I was told it needs to be installed with in 18 inches of the point it comes up out of the ground. I can not find this in the code could some one point me in the right direction.
I don't know about the 18" part unless it is a local thing. Someone else might be able to help with that.
 

kwired

Electron manager
Location
NE Nebraska
The 18 inch rule you are thinking of is probably the one that says that you need a seal within 18 inches of an enclosure containing arc producing components like a switch, contactor, overcurrent device, etc.
 

Smart $

Esteemed Member
Location
Ohio
Within 10' either side of the boundary is pretty straight forward. The boundary isn't always something tangible, but let's say it is a wall for the sake of discussion. Your seal off has to go within 10' of the conduit run measured from where the wall is penetrated, on either side of the wall.

You first have to determine where your boundary is. It may just be an imaginary hemispherical or cylindrical area above the well and around its vent stack.
 
The way it was told to me is there needed to be one with in 18" of the wet well but since the pipe is under ground for about 12 feet till it reaches a point where I can install a seal off the that I needed to have one with in 18 inches of the point it comes up from the ground.
 
Within 10' either side of the boundary is pretty straight forward. The boundary isn't always something tangible, but let's say it is a wall for the sake of discussion. Your seal off has to go within 10' of the conduit run measured from where the wall is penetrated, on either side of the wall.

You first have to determine where your boundary is. It may just be an imaginary hemispherical or cylindrical area above the well and around its vent stack.
Thank you I could not picture the term " either side of the boundry for my application. The boundary for me would be the point it leaves the wet well. Well that point is underground for about 12 feet. So I was told that I would need one with in 18 inches after it comes up from tue ground.
 

Smart $

Esteemed Member
Location
Ohio
The way it was told to me is there needed to be one with in 18" of the wet well but since the pipe is under ground for about 12 feet till it reaches a point where I can install a seal off the that I needed to have one with in 18 inches of the point it comes up from the ground.
Your description needs clarification. I cannot determine where the 12' of conduit underground is. Is it down in the well or between the control panel and where it goes down in the well. Describe the run, from control panel to where it ends down in the well. Give distances up, down, right, left, frontward, backward, underground, above grade, etc...
 
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Smart $

Esteemed Member
Location
Ohio
Thank you I could not picture the term " either side of the boundry for my application. The boundary for me would be the point it leaves the wet well. Well that point is underground for about 12 feet. So I was told that I would need one with in 18 inches after it comes up from tue ground.
Are you sure grade level of the well is the boundary. Is it vented at all nearby? There is typically an area around any vent that is classified hazardous. Does the well itself have a solid cover and no vent holes?
 
Your description needs clarification. I cannot determine where the 12' of conduit underground is. Is it down in the well or between the control panel and where it goes down in the well. Describe the run, from control panel to where it ends down in the well. Give distances up, down, right, left, frontward, backward, underground, above grade, etc...
Sorry. The pipe is between the wet well and control panel. It only goes in to the well about 6 inches. It runs from the well underground for about 12 foot and then stubs up under the control panel. See attachments.
 

Attachments

Are you sure grade level of the well is the boundary. Is it vented at all nearby? There is typically an area around any vent that is classified hazardous. Does the well itself have a solid cover and no vent holes?
The well has a solid cover and one vent pipe.
 

iMuse97

Senior Member
Location
Chicagoland
Sorry. The pipe is between the wet well and control panel. It only goes in to the well about 6 inches. It runs from the well underground for about 12 foot and then stubs up under the control panel. See attachments.
With reference to your second drawing, I've put the seal-offs right where the pipe leaves the ground under the control panel on a couple different jobs. Project engineers and town engineers and GC's all cool with it.

Also note that the several disconnects, and some other boxes were FS ("explosion-proof") type enclosures. My underground runs were about 12 feet horizontally also.
 
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With reference to your second drawing, I've put the seal-offs right where the pipe leaves the ground under the control panel on a couple different jobs. Project engineers and town engineers and GC's all cool with it.
That is how we generally do it. These pumps sites are my first job like this and I am just trying to learn the best I can and my drawings give no guidance with this at all. On past jobs I have helped on it has been in the specs.
 

Smart $

Esteemed Member
Location
Ohio
That is how we generally do it. These pumps sites are my first job like this and I am just trying to learn the best I can and my drawings give no guidance with this at all. On past jobs I have helped on it has been in the specs.
Well your thread title (though actually Article 501, not 500) implies Class 1 Division 2 location...

If the well were Class 1 Division 1, 501.15(A)(4) Exception No. 2 would permit you to put your seal between the point of emergence and the control box, with no prohibited "parts" between emergence point and seal (such that you could actually have up to a full stick of conduit before putting a seal fitting in the run).

Yet for Class 1 Division 2 location, you either have to abide by the 10' requirement or qualify your conduit run under 501.15(B)(2) Exception No. 4 (i.e.. Exceptions No'd 1 through 3 do not apply)....
 

kwired

Electron manager
Location
NE Nebraska
514 which is for motor fuel dispensing does describe running underground to non classified area and being able to place the seal within 10 feet from emerging out of the ground.

Unfortuneately you are not connecting motor fuel dispensing equipment and there is no section specific to what you are doing. The general sections of 500-506 do not have anything in them that mentions underground installations.
 

Smart $

Esteemed Member
Location
Ohio
Yeah my bad is there anyway to edit The title of this post.
A moderator may come along and do it for you. The edit time permitted for you to edit it has been expired for some time now.

No biggy, though. The knowledgeable know what you meant... :?
 

kwired

Electron manager
Location
NE Nebraska
If the well were Class 1 Division 1, 501.15(A)(4) Exception No. 2 would permit you to put your seal between the point of emergence and the control box, with no prohibited "parts" between emergence point and seal (such that you could actually have up to a full stick of conduit before putting a seal fitting in the run).

Yet for Class 1 Division 2 location, you either have to abide by the 10' requirement or qualify your conduit run under 501.15(B)(2) Exception No. 4 (i.e.. Exceptions No'd 1 through 3 do not apply)....
I read through all of that yet somehow it did not register at the time that that was what I was looking for. :slaphead:
 

rbalex

Moderator
Staff member
I revised the title for you.

FWIW, 501.15(B)(2) Exception No. 4 does't apply either, because the entire segment from terminus to terminus is not outdoors. [501.15(B)(2) Exception No. 4 (2)]
 

rbalex

Moderator
Staff member
See 501.15 FPN No. 1.

Basically,seals have two purposes: “… to minimize the passage of gases and vapors and prevent the passage of flames from one portion of the electrical installation to another through the conduit.”

I call seals “…to minimize the passage of gases and vapors … from one portion of the electrical installation to another through the conduit,” boundary seals and those that “…prevent the passage of flames from one portion of the electrical installation to another through the conduit,” integrity seals. In some cases a single seal fitting may accomplish both functions. Notice boundary seals are only intended to minimize passage while integrity seals are intended to prevent passage.

In Class I, integrity seals are associated with maintaining the integrity of explosionproof enclosures; generally enclosures containing arcing, sparking or heat producing (ASH) devices. This applies to both Division 1 and 2. The seal fitting must listed explosionproof and within 18” of the enclosure it is protecting.

A “boundary” exists between Division 1 and Division 2 or unclassified locations,and Division 2 and unclassified locations. Assuming the boundary has been properly defined, a boundary seal must be located within 10’ of either side of the boundary. Seals between Division 1 and Division 2 or unclassified locations must be listed explosionproof. Seals between Division 2 and unclassified locations are not required to be explosionproof (or listed for that matter except by the requirements of their respective wiring method.)

There are both Exceptions and additions, but the above are the “general”rules.
 
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