MC Cable Supported by MC Cable

[hbendillo]

I am an engineer and recently performed an field inspection on a project for which our AE company was the design firm. It is a health care occupancy and in particular an Critical Care ward. I was not a part of the original design team.

Value engineering was done on the project to use MC cable. I do not have many projects in which I have been involved where MC cable was used and none in a Health Care Occupancy. Among other issues I am having with the Contractor is using MC cable to support other MC cable in a bundle. The Contractor claims that one can support up to two MC cables to another MC cable that is supported and fastened according to code requirements. In other words one MC cable fastened and supported and the other two tie-wrapped to it. I cannot find where that is explicitly allowed. I am thinking he may be confusing the derating requirements of bundled MC cables.

Can anybody guide me to the requirements for this condition?

 

[infinity]

The NEC doesn't specify how it's supported so it's really a judgement call by the AHJ unless something in the specification for the job dictated how it was to be done. I don't see a problem bundling a few cables together and strapping only one since cable ties are permitted for securing MC cables.

 

[petersonra]

take a close look at 300.11 (D)

 

[macmikeman]

Speaking of 300.11 (D) , I have seen electrical inspectors get pretty excited over finding electrical cables supported from other mechanical systems such as the 3/8" rod suspending a sprinkler pipe, or mc cable draped over air ducts in suspended ceilings. But does such a preventative code exist in the electrical code book? (I realize that it may be prohibited someplace in lets say the plumbing code or the sprinkler code or some such, but specifically how about the NEC?)

 

[augie47]

On a related note, can MC be used (other than fished) for critical care areas ?

 

[hbendillo]

On a related note, can MC be used (other than fished) for critical care areas ?

That is our other big issue with this project. Our interpretation of the NEC is that MC cable cannot be used for Life Safety and Critical circuits in critical care spaces. Or maybe patient care spaces at all. I am still doing research for my field report for my recent site inspection.

 

[petersonra]

That is our other big issue with this project. Our interpretation of the NEC is that MC cable cannot be used for Life Safety and Critical circuits in critical care spaces. Or maybe patient care spaces at all. I am still doing research for my field report for my recent site inspection.

Take a look at 517.31 (C)(3)

I only looked because I could swear I have seen MC used in hospitals. But I might have been rememerbing wrongly.

 

[augie47]

Take a look at 517.31 (C)(3)

I only looked because I could swear I have seen MC used in hospitals. But I might have been rememerbing wrongly.

Its fine (as Mc-CAP), I think, until you get to critical care

 

[JFletcher]

Unless it is in the manufacturer's instructions for the MC cable, it cannot support other MC cables, 300.11. I have never seen such a statement on any manufacturer website or spec sheet for MC cable. All of the cables have to be supported by J Hooks, the building surface, Unistrut, Etc. they can be zip tied together, but say you forgot to run two MC cables, or two were added, you cannot zip tie those cables to the bundle and not have them supported otherwise. I think the contractor is trying to pull a fast one on this

 

[JFletcher]

Speaking of 300.11 (D) , I have seen electrical inspectors get pretty excited over finding electrical cables supported from other mechanical systems such as the 3/8" rod suspending a sprinkler pipe, or mc cable draped over air ducts in suspended ceilings. But does such a preventative code exist in the electrical code book? (I realize that it may be prohibited someplace in lets say the plumbing code or the sprinkler code or some such, but specifically how about the NEC?)

the NEC only addresses electrical conduits, other cables, and ceiling grids. It does not address strapping cables to other systems, like plumbing, sprinkler pipe Etc. building codes do address these though, and that was one of the first things I learned when doing communication work... Run your own supports. strapping Comm cable to plumbing pipe, EMT, sprinkler pipe, anything pretty much we'll get a red tag from the inspector

 

[macmikeman]

the NEC only addresses electrical conduits, other cables, and ceiling grids. It does not address strapping cables to other systems, like plumbing, sprinkler pipe Etc. building codes do address these though, and that was one of the first things I learned when doing communication work... Run your own supports. strapping Comm cable to plumbing pipe, EMT, sprinkler pipe, anything pretty much we'll get a red tag from the inspector

Yes. I prefer to use bridle clips from Caddy. I use the 1/4" threaded end to go into a drop in anchor I drill the concrete structure for. Then I string my com's thru the bridle clips. Some of them I pre paint dark red and then use those for FA cables. It's the existing stuff left behind by the other remodels that the inspectors are jumping up and down over. The sloppiness contrasts pretty much to my work. They get jumpy about the other guys who seem to have never read the parts about supporting cables above ceiling tiles.

 

[roger]

Its fine (as Mc-CAP), I think, until you get to critical care

Actually HFC can be used in Critical Care areas even in new construction for Normal Branch wiring, it can not be used for the Critical or Life Safety Branches unless it meets the conditions of 517.31(C)(3)(3) as mentioned by Bob.

Roger