Conduit Seals 501.15 (B) 2

[ecuinc]

I have four 3/4" rigid conduits comming out of the concrete going up to a control panel. I have installed seal off's about 9'' above the concrete. There is a coupling between the conrete and the seal off's. The area is a Class 1 Div 2. From the seal off to the control panel is a conduit with no breaks in it.
My question is, i was told i coudnt have the couplings between the seal off's and the concrete. I was looking at 501.15 (B) 2.

Thank you,
Robert

 

[KentAT]

Assuming your concrete is a boundary between your Div 2 loacation and an unclassified area, you are looking in the right place, and what you were told is correct - a coupling is not allowed unless you meet one of the exceptions listed. For the exceptions, you are being allowed to install without a seal to begin with, so the seal and coupling combination doesn't matter.

Read the sentence beginning with "Except for listed reducers..."

If I am wrong, others will correct me shortly...:smile:

Kent

 

[StreamlineGT]

As I understand it, having the coupling is a violation.

 

[stormywyo]

The coupling is a violation of the NEC in this application..

 

[ecuinc]

More info! The curb is 9" tall and the seals are at 18" from finished grade. So wouldnt my Class 1 Div 2 boundary be at the 18" mark above finish grade. If so, the code states that no fitting between the boundary and the seal. If i'm reading that right i'm in compliance with 501.15 (B) 2.

 

[KentAT]

More info! The curb is 9" tall and the seals are at 18" from finished grade. So wouldnt my Class 1 Div 2 boundary be at the 18" mark above finish grade. If so, the code states that no fitting between the boundary and the seal. If i'm reading that right i'm in compliance with 501.15 (B) 2.

A seal does not define the boundary, if this is what you are asking. The boundary is defined by proper application of an engineering standard depending on the nature of the installation, such as using API RP500, and proper protection techniques must be used (wiring methods, materials) to ensure a safe installation.

That being said, you need a hazardous area classification drawing which identifies the hazardous areas of this installation. Then you know how to install the equipment safely and where to put your seals.

So, where is the boundary between your Div 2 area and the unclassified area? Are you saying your Div 2 area stops 18" above grade?

Is there any more info you have left out? You mention a curb, is this a gas station, or something?

 

[rbalex]

More info! The curb is 9" tall and the seals are at 18" from finished grade. So wouldnt my Class 1 Div 2 boundary be at the 18" mark above finish grade. If so, the code states that no fitting between the boundary and the seal. If i'm reading that right i'm in compliance with 501.15 (B) 2.

You have already been given solid advice by all the previous responders. I would like to add a few comments. We do not know what standard was used to determine the area classification; e.g. NFPA 497. Therefore, we don't know how the 18" upper boundary was determined. Depending on the application, the upper boundary may be 18", 24", or possibly 36". While it isn't too likely, it could even be more readily measured in feet than inches.

In addition, while it may not be immediately obvious, there are actually two boundaries. The upper one you already seem to recognize, but there is also one at the concrete.