330.12 as applied to Type MC-HL cable

[controlsguy]

I am looking for a second opinion on how 330.12 (1) applies to type MC-HL or Okonite C-L-X when installed in an installation open to authorized personnel only. The application's goal is to replace a cable tray or conduit and wire system with MC-HL (CLX) supported by process piping and process piping supports in lieu of an independent support system. This is a power limited (controls) installation with the cable being installed in the following manner:

1. direct burial
2. affixed to process piping and process piping supports in lieu of an independent support system.
3. passing through and also terminating in class 1, div 1 and div 2 locations.

I believe that MC-HL or CLX is an acceptable wiring method for this application when terminated and supported appropriately except where the cable might be exposed to physical damage at the lower (near ground level) elevations of the proposed installation. The "physical damage" risk at the lower elevations would be from personnel working on the equipment and not truck or equipment traffic.

Would the crush rating of the MC cable or installation of gaurding around the lower elevations in lieu of cable tray or conduit negate 330.12 (1)?

Thanks in advance for your help.

 

[rbalex]

...
Would the crush rating of the MC cable or installation of gaurding around the lower elevations in lieu of cable tray or conduit negate 330.12 (1)?
...

Crush & impact rating - NO, especially in high traffic areas, motorized or not. Guarding by location or mechanical means is fine.
Make sure the cable is suitable for direct burial and any potential corrosive properties of the materials involved; i.e., check 330.12(2) also. Review the process piping for thermal issues that may affect both the cable and support. Remember the cable must be supported at 6' intervals.

 

[controlsguy]

Thank you for your post. I have not been able to find an objective manner to define the requirements of 330.12 (1). This requirement seems completely subjective to me. I do have a specific situation I am questioning.

Application Criteria:

1) The location is an industrial location with authorized personnel only and maintenance staff.
2) The subject location contains Class 1, Div 1 and Div 2 areas.
3) The CLX or MC-HL cable is rated for direct burial, has polymeric jacket and is terminated with proper sealing fittings where required.
4) The subject cable(s) exit the ground and are routed directly to steel framing members supporting production equipment or site poured concrete pads supporting production vessels.
5) The process equipment is located in such a manner to minimize foot traffic in close proximity to the cable exiting the ground and entering the support structure.
6) No corrossives present.


The test required by 330.12(1), "where subject to physical damage" is, in my opinion, completely subjective. In the above example, the cables are protected by location from heavy traffic. I suppose to insure compliance one could add mechanical gaurding to protect the cable(s) where the transition from burial to the framing members occurs.

My initial question regarding the crush and impact ratings of the cable was intended to find an objective way to satisfy a subjective requirement. If the crush ratings are above what a normal person would reasonably apply with incidental foot contact to the cable, then it would be reasonable to conclude that 330.12 (1) is satisfied.

I suppose it is futile to search for an objective test for the subjective. Then perhaps, the better question is, "What methodology do you apply to insure compliance with 330.12(1)?"

 

[rbalex]

You definitely won't find a "bright line" objective test, this is one reason we have AHJs and their agents. On the other hand, it is still usually pretty obvious where a cable is likely to be subject to damaging contact without some physical protection. In cases where it's questionable - beef it up.

You gave a good example where the cable emerges from ground. If it's remote from routine foot traffic and not subject to falling objects from work above, you could probably use minimal physical protection, maybe none at all. As the likelihood of contact becomes greater, consider additional protection.

 

[controlsguy]

rbalex, thank you for your post(s).

I understand. Ultimately, common sense (tempered with application knowledge) should prevail, or at least a good argument for what reasoning was applied to the design.