Hazardous Areas - Class 1, Div 2 Area - Multiconductor Cable in Conduit

[meisenb]

Hi - I have a question about a wiring method in a C1, D2 area for lighting fixtures (NEC, USA job). My scope of work does not leave the C1, D2, but will interface eventually back to an unclassified area. The start of the wiring is from a terminal junction box (NEMA 4X) , where it exits the junction box in a compression type cable gland and continues on in the cable tray to the first fixture (not factory sealed). The fixtures are HPS stanchion mount, meaning that the TC cable goes through an open conduit system and the wires terminate inside the light fixture without a cable gland or any type of sealing. The wires are connected with wire nuts, and the wiring to the next fixture goes down the same conduit and back into the cable tray. Eventually the it makes sense to continue the wiring in conduit at the ends of the runs, and the last fixtures in each run are fed with the same cable - TC, but now in an open conduit system - meaning I do not have any conduit seals when it transitions to conduit.

My question is this... I feel like when I read the code to determine whether I need cable seals or conduit seals between fixtures using this wiring method, it takes me in a loop where I can come up with two different answers. I understand that normally light fixtures would not require seals between each fixture, I'm getting hung on my wiring method.

First - 501.15(E)(1) Terminations.... Is initally talking about requiring seals where entering explosionproof boxes/enclosures. (This is not me.) , but the last sentence is "Multiconductor cables in conduit shall be sealed as described in 501.15(D)", which leads you back to C1, D1. So at every termination - every light fixture would have to be sealed. Or..... Does this last sentence only pertain to multiconductor cable in conduit entering explosionproof boxes?

Second - 501.15(E) (3) Talks about Cables Capable of Transmitting Gases or Vapors (This is me.) So this now tells me that it is not required, except for when required by 501.15(E), which is obviously listed above...


Last - My gut is telling me that the only location seals are required is on the boundary back to the unclassified area, but would like someone with more experience to confirm this. I understand that I am looking for some education. Any direction to articles, other posts, books to read on topic would be recieved well.... Thanks in advance.

 

[rbalex]

Welcome to the forums. If you had posted this in the Hazardous (Classified) Locations forum, it may have been answered earlier.

The last two sentences in Section 501.15(E)(1) are telling you IF you have a multiconductor cable AND it is required to be sealed at the termination THEN seal it as described in 501.15(D). No other seal is required for the cable itself.

Eighteen years ago, I was on a different Code Making Panel (CMP 11) when Section 501.15(E)(1) was essentially crafted in its current form. I warned several members of CMP14 that that last sentence would be a problem but they dismissed it on the basis of Section 90.1(C). Until just recently, they appeared to be right. Maybe they still are.

 

[GoldDigger]

I warned several members of CMP14 that that last sentence would be a problem but they dismissed it on the basis of Section 90.1(C). Until just recently, they appeared to be right. Maybe they still are.

And one response to their appeal to 90.1(C) would be that the code is not intended as a recreational book of logic puzzles either.

At one time HP had (and maybe they still have) a documentation writing standard that no piece of information should ever appear in more than one place in a given document or set of documents. Made for a lot of long chains of cross references when trying to look something up.

 

[weressl]

Hi - I have a question about a wiring method in a C1, D2 area for lighting fixtures (NEC, USA job). My scope of work does not leave the C1, D2, but will interface eventually back to an unclassified area. The start of the wiring is from a terminal junction box (NEMA 4X) , where it exits the junction box in a compression type cable gland and continues on in the cable tray to the first fixture (not factory sealed). The fixtures are HPS stanchion mount, meaning that the TC cable goes through an open conduit system and the wires terminate inside the light fixture without a cable gland or any type of sealing. The wires are connected with wire nuts, and the wiring to the next fixture goes down the same conduit and back into the cable tray. Eventually the it makes sense to continue the wiring in conduit at the ends of the runs, and the last fixtures in each run are fed with the same cable - TC, but now in an open conduit system - meaning I do not have any conduit seals when it transitions to conduit.

My question is this... I feel like when I read the code to determine whether I need cable seals or conduit seals between fixtures using this wiring method, it takes me in a loop where I can come up with two different answers. I understand that normally light fixtures would not require seals between each fixture, I'm getting hung on my wiring method.

First - 501.15(E)(1) Terminations.... Is initally talking about requiring seals where entering explosionproof boxes/enclosures. (This is not me.) , but the last sentence is "Multiconductor cables in conduit shall be sealed as described in 501.15(D)", which leads you back to C1, D1. So at every termination - every light fixture would have to be sealed. Or..... Does this last sentence only pertain to multiconductor cable in conduit entering explosionproof boxes?

Second - 501.15(E) (3) Talks about Cables Capable of Transmitting Gases or Vapors (This is me.) So this now tells me that it is not required, except for when required by 501.15(E), which is obviously listed above...


Last - My gut is telling me that the only location seals are required is on the boundary back to the unclassified area, but would like someone with more experience to confirm this. I understand that I am looking for some education. Any direction to articles, other posts, books to read on topic would be recieved well.... Thanks in advance.

Outside of the XP sealing requirement a fundamental wiring error is present with the use of 'open conduit' system you describe. The TC cable should be terminated with a CABLE fitting when it enters the lighting fixture. A truly open conduit would NOT connect to any devices, be it a junction box or a luminaire. If you connect the luminaire to a conduit, usually stanchion mount where the conduit itself is the supporter of the luminaire, that conduit is no longer an 'open conduit' - (a cable support system which has no definition or recognition in the NEC -, but a regular conduit and as such, wherever the cable is connected to it, it should use a cable connector such as CGB, etc. Any opening in a raceway or electrical enclosure should be made with a device that is designed and listed for that purpose and essentially should maintain the NEMA rating of the entity. Ex. a NEMA 4X box should not have a NEMA 1 rated connector to it.

 

[meisenb]

Outside of the XP sealing requirement a fundamental wiring error is present with the use of 'open conduit' system you describe. The TC cable should be terminated with a CABLE fitting when it enters the lighting fixture. A truly open conduit would NOT connect to any devices, be it a junction box or a luminaire. If you connect the luminaire to a conduit, usually stanchion mount where the conduit itself is the supporter of the luminaire, that conduit is no longer an 'open conduit' - (a cable support system which has no definition or recognition in the NEC -, but a regular conduit and as such, wherever the cable is connected to it, it should use a cable connector such as CGB, etc. Any opening in a raceway or electrical enclosure should be made with a device that is designed and listed for that purpose and essentially should maintain the NEMA rating of the entity. Ex. a NEMA 4X box should not have a NEMA 1 rated connector to it.

You are indicating to use a cable fitting at the entrance to the conduit. I'm assuming that you are indicating that I would locate those at the "TB" fitting at the bottom of the conduit for the stanchion mount. One for the cable entering the conduit up to the fixture, and one as the cable leaves the fixture. I have one other cable in this conduit for the emgency lighting. The customer indicated that they do not want junction boxes, but I do not see how I would accomplish this installation without one. Does anyone have any good locations I can look for installation details on this type of thing? I am looking for training on this topic. Any good resources?