m.c. cable on a block wall

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big phil

Member
What do you think about running m.c.cable on a block wall? we had an inspector make us remove it and run e.m.t. he said that you can not run m.c. cable on a block wall. I do not agree with this. Tell me what you think,I can not find a code violation in the n.e.c.
 

websparky

Senior Member
Location
Cleveland, Ohio
Re: m.c. cable on a block wall

Hi Phil,

Here are the ones that are usually sited.
330.10 Uses Permitted.
(A) General Uses. Where not subject to physical damage,
(11) In dry locations and embedded in plaster finish on brick or other masonry except in damp or wet locations
(12) In wet locations where any of the following conditions are met:
a. The metallic covering is impervious to moisture.
b. A lead sheath or moisture-impervious jacket is provided under the metal covering.
c. The insulated conductors under the metallic covering are listed for use in wet locations.
 

tonyi

Senior Member
Re: m.c. cable on a block wall

If there's dampness/leaching through the wall, then avoid it if its alum armor. Concrete is alkaline can eat up the alum armor over time (I've seen some pretty eaten up armor). In a case like that I'd strap up some PVC and shoot the MC through the PVC where it would be in contact otherwise.
 

msd

Senior Member
Re: m.c. cable on a block wall

330.10 A (11) In dry locations and embedded in plaster finish on brick or other masonry except in damp or wet locations.

(Read)embedded in plaster, "not on the surface" and not in damp/wet locations.
 

big phil

Member
Re: m.c. cable on a block wall

the m.c. cable is straped to the inside wall between the fern strips and then covered with sheet rock. I don't see how that could be a problem.
 

iwire

Moderator
Staff member
Location
Massachusetts
Re: m.c. cable on a block wall

Originally posted by big phil:
the m.c. cable is straped to the inside wall between the fern strips and then covered with sheet rock. I don't see how that could be a problem.
Now with this added info the inspector might have failed you for this.

300.4(D) Cables and Raceways Parallel to Framing Members. In both exposed and concealed locations, where a cable- or raceway-type wiring method is installed parallel to framing members, such as joists, rafters, or studs, the cable or raceway shall be installed and supported so that the nearest outside surface of the cable or raceway is not less than 32 mm (1 1/4 in.) from the nearest edge of the framing member where nails or screws are likely to penetrate. Where this distance cannot be maintained, the cable or raceway shall be protected from penetration by nails or screws by a steel plate, sleeve, or equivalent at least 1.6 mm (1/16 in.) thick.

Exception No. 1: Steel plates, sleeves, or the equivalent shall not be required to protect rigid metal conduit, intermediate metal conduit, rigid nonmetallic conduit, or electrical metallic tubing.
So if you had the MC strapped parallel to the firring strips I do not see how you could stay 1 1/4" back.
 

big phil

Member
Re: m.c. cable on a block wall

hey, that is an excellent point I'm glad you brought this up I will let everybody know. But, we must wonder why they will not fail you on romex used in the same application.
 
Re: m.c. cable on a block wall

Originally posted by big phil:
But, we must wonder why they will not fail you on romex used in the same application. [/QB]
I know my inspector would fail me if i did that.

The carpenter I work with always frames a new wall an inch or so off of the existing block, brick, or stone foundation. In this manner I don't have the 1 1/4" problem or the wire against block problem.


When carpenter builds nice, new, level, plumb walls and square rooms its easier for me(electrical), the sheetrocker, etc.,

Cost difference is not that much, room space is not much different ,helps with possible moisture factors.

[ March 28, 2004, 08:55 PM: Message edited by: mjf ]
 

big phil

Member
Re: m.c. cable on a block wall

hey mjf, we always take a zip tie with a hole at the end of it and put a drive pin through it and hammer them to all the exterior walls between the fern strips where we will have recps. and switches.Then when we run our romex down the wall we just tighten the zip tie around the romex. We just practice this in our res. work but we have never been failed for such ,and there is never added fern strips to give the extra depth to the wall,although that is a really good idea and I like the thought of that.Give me your thought on this application and why we can do this and not get failed but with the m.c. it is a different story. unless, the com. part of it is more strict.
 
Re: m.c. cable on a block wall

big phil,
I like the zip tie idea, but I still don't like only 3/4 inch between block and sheet rock. I don't think my inspector would like to see it. He would probably figure "imminent danger", and that's a judgement call he can make or not make.


To tell you the truth I have very little commercial experience, so I can't really comment on that.
 

big phil

Member
Re: m.c. cable on a block wall

mlf, I will agree on the 3/4 inch space with you. espcially when you are talking about an exterior wall and someone could take a picture and hang it up and get the romex with a screw. That would be a nightmare service call. Now that we have discussed it I will change my ways. do you use e.m.t. on all your block walls?
 
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