Class 1 Div 1 Cables and Seals

[jstauffe]

Hi,

I'm new to this forum, but looking at some of the posts folks seem very knowledgeable here. I am overseeing the installation of a coating line into a class 1 div 1 location. The electrical cabinet is located outside of the hazardous area ~100ft from the machine, so all drive cables and IO need to be run into the classified area. We were thinking about running trough from the control cabinet to just outside the room, which is separated by a wall from the classified area, and then conduit from the trough, through the wall, into the classified room. I hit a snag in this plan when investigating multi-conductor cable and the seals.

The machine manufacturer has suggested several different Beldin Cable types ranging from VFD cable(29511) to multiconductor IO(27103A). I'm trying to figure out the different options from a cabling and sealing perspective to balance cost and complexity. These are the options as I see them.....

1. Use the suggested cable, breaking the multiconductor sheaths in the seals at the penetration into the classified area, and in non-intrinsically safe cases doing the same at the connection points with motors etc. Doing this I have questions around the 501.15.D.1 exception, as the VFD cable is shielded, I have encoder cables that are shielded twisted pair, and I have an ethernet cable. Can they each be sealed as a single conductor, or should they be broken apart? How do I interpret 'approved means to minimize the entrance of gasses....'?

2. Use a home run of MC-HL cable from my cabinet to the machine. This can eliminate any conduit runs, assuming I have cable tray or some way to support it. It also allows sealing as a single conductor at the area penetration point, and using the appropriate fittings to seal at the other end, it makes a clean installation. This stuff appears to be quite big and possibly cumbersome, as some of my cables are 25 conductor. Is it cost effective over conduit, seals, flex couplings, etc? I am interested in any experience you guys have with it.

3. Run the suggested cable in trough, hit a junction box outside the area, use MC-HL cable to penetrate the wall through conduit, which allows sealing as a single conductor. Once sealed, run the MC-HL in cable tray, and use appropriate MC-HL seals at the other end of the cables.

4. Just run single conductor wire from the cabinet to the machine. This gets messy fast, has potential noise issues with the VFD's (9 of them), but eliminates the multiconductor sealing issue.

Based on what I've read here, and what my electricians are telling me, sealing a multiconductor cable is difficult. Is it impossible? Also I am concerned with breaking the shield on the VFD and encoder cables, as the run is somewhat long and I don't want to introduce noise into the system.

I am looking for feedback on these options. Are they sound? Have I missed anything? Is there a better way? Any help would be greatly appreciated!

Thanks,
Jonathan

 

[rbalex]

This appears to be an Article 516 application.

Personally, I?d go with Type MC-HL and ITC-HL cables with TMCX sealing fittings in the Division 1 location and TMC fittings in the unclassified location. The cables will not require boundary seals at the wall. A substantial mastic type wall seal around the cables at the wall is recommended but not absolutely necessary if a small Division 2 location (typically 3 feet) around the penetration is acceptable.

 

[BPoindexter]

I have literally seens thousands of cables done exactly as Bob describes and think it is by far the best way to go. TMCX connectors are not that hard to make up. They have newer types that are even easier to use with an expanding sealing material. Use explosion proof unions where they terminate- they are supposed to be reusable but in practice are not always the easiest thing to do so. Using unions keeps the integrity of the TMCX intact and easier for de-termination and re-termination.

The only caveat I would say to this is where you may have multipaired shielded cable for instrumentation such as the home run to an instrumentation termination box. Most of the time we do not break them apart at the seal or fitting in order to maintain the shield isolation. Bring the inner sheath through and then apply cable sealing to it inside the enclosure and you can run your shields close to the actual termination point.

 

[jstauffe]

Thanks to you both for your help. I priced the MC-HL option, and it is considerably cheaper than conduit, fittings, seals, flex, and wire. I am definitely leaning that direction from a cost and ease of installation perspective. This is new to me and my electrician, so we have a couple of install questions. We plan to run this MC-HL cable in cable tray, penetrate drywall into an area that is not classified, then continue with the cable tray into the classified area. From there we drop out of the cable tray to the machine. In some spots we will be penetrating sheet metal guarding before landing at motors, encoders, sensors, etc.

Do I need to protect this cable when penetrating drywall and sheet metal? If so what do you recommend?

You mention TMC fittings in the non-classified area. Do these fittings seal at the other end, or do they not need to?

How does this cable get around the 'seal when leaving the classified area' requirement?

Do I treat intrinsically safe circuits the same with this cable, as in seal them at the end with TMCX fittings?


Thanks,
Jonathan

 

[rbalex]

Thanks to you both for your help. I priced the MC-HL option, and it is considerably cheaper than conduit, fittings, seals, flex, and wire. I am definitely leaning that direction from a cost and ease of installation perspective. This is new to me and my electrician, so we have a couple of install questions. We plan to run this MC-HL cable in cable tray, penetrate drywall into an area that is not classified, then continue with the cable tray into the classified area. From there we drop out of the cable tray to the machine. In some spots we will be penetrating sheet metal guarding before landing at motors, encoders, sensors, etc.

…

Thanks,
Jonathan

Edit add: It better not be "cheaper"; just more "cost effective."

• Do I need to protect this cable when penetrating drywall and sheet metal? If so what do you recommend?

No extraordinary protection is needed.

• You mention TMC fittings in the non-classified area. Do these fittings seal at the other end, or do they not need to?

No seal is needed in the unclassified location.

• How does this cable get around the 'seal when leaving the classified area' requirement?

What requirement is that? You are sealing per 501.15(D)(1)&(2). The seal at the termination is doing “double-duty”.

• Do I treat intrinsically safe circuits the same with this cable, as in seal them at the end with TMCX fittings?

You could. Technically, the intrinsically safe system doesn’t even need a TMCX. See Section 504.70; however be careful to observe all the Article 504 requirements.

 

[jstauffe]

Haha! Yes you are correct. It is maximizing the cost effectiveness of the project. Thanks for your insight. I really appreciate it.

Jonathan

 

[steve_myc]

sealing 24 pair hl instrument cable rated abcd

sealing 24 pair hl instrument cable rated abcd

From canada.

Can we pour around (teck cable) the inner jacket instead of seperating all pairsfrom eachother. I makes sense other wise you would have possible chance of damaging mylar.

Should we seal around a teck fibre- optic cable

I need help quick please fellas help me out

 

[rbalex]

From canada.

Can we pour around (teck cable) the inner jacket instead of seperating all pairsfrom eachother. I makes sense other wise you would have possible chance of damaging mylar.

Should we seal around a teck fibre- optic cable

I need help quick please fellas help me out

Probably. I don't have access to a current Canadian Electrical Code (CEC), but the NEC doesn't require separating instrument pairs. See the exceptions to Sections 501.15(D) (1)&(2).

Note: TECK-90 and Type MC-HL are not the same.