Class I Div 2 junction boxes

[mphymel]

In a Class 1 Div 2 areas, I have routinely seen stainless steel NEMA 4x enclosures installed to house industrial instrumention terminations (junction boxes), 24 volt analog (4-20mA) and disrete signals. Rigid metal conduit is used to bring in signal wiring.

No arc producing devices or heat generating equipment is installed in these boxes, however, the ciruits are not intrinsically safe, and I doubt that the installations were designed to be non-incendive. (although if tested they may meet the requirements)

I think the general perception is that instrument terminations have not the capacity to generate enough heat for ignition.

These boxes are often not purged. Are these in violation of code?

Furthermore... If a Z purge is to be installed, is the use of duct sealing for conduits a sufficient sealing mechanism or would conduit seals be required to meet code?

 

[don_resqcapt19]

Re: Class I Div 2 junction boxes

Junction boxes in a Class 1 Division 2 area that contain only splices and not equipment can be NEMA 1 or whatever you need for the environment that is in the area. There is no requirement that the wiring in the box be IS or non-incendive type circuits. 120, 480 or even 5kV could be spliced on open terminals in a Div 2 area using a NEMA 1 box.
Don

 

[mphymel]

Re: Class I Div 2 junction boxes

Thanks for the response.

Since this is true, in 501.5(E)(1), does the following clause preclude the next statement concerning multiconductor cables?

"Cables entering enclosures that are required to be explosionproof shall be sealed at the point of entrance..."

which is followed later by...

"Multiconductor cables with a gas/vaportight continuous sheath capable of transmitting gases or vapors through the cable core shall be sealed in a listed fitting in the Division 2 location after removing the jacket and any other coverings so that the sealing compound surrounds..."

In other words, if a non-explosion proof box is being used as a junction box only, and multi-conductor cables enter the box from conduits leading to cable tray, is it necessary to provide conduit or cable seals, since the box is not capable of containing an explosion should one occur?

 

[don_resqcapt19]

Re: Class I Div 2 junction boxes

If the box is not required to be explosionproof, no seals are required.
Don