What are the inspectors saying about using MC cable, (interlocked) installed for a drop for a laundry plug etc. when it is in contact with a masonry wall? No PVC jacket on the cable and does it need physical protection? Maybe I'm too strict. I say no way.

So long as it is dry and secured properly, I see no problem. If there is a concern with physical protection, sleeve it in EMT or PVC.

What is your concern, what do you cite and what would you accept? RNC uses the same "physical damage" language.
Do you want it on a running board (corrosion issue) or do you want it sleeved in RMC?

Dean, most MC is listed "wet" these days. It has dual rated THHN/THWN conductors in it.

What about the aluminum jacket?

What's wrong with the aluminum jacket? Is your concern a reaction with the block wall or a damage issue?
I am still curious what your cite is.
I know "damage" is a local call and the local practice varies widely across the country, even from AHJ to AHJ in the same general area. In Md it is common to simply staple Rx on running boards in utility areas. In this area of Florida that is not OK but they will take ENT (smurf). Other areas set the minimum at EMT.
I have not heard about concerns about MC, one way or the other.



[This message has been edited by gfretwell (edited 11-01-2006).]

Greg- I guess that's why I posted the issue. I know we can't have aluminnum wire in contact with concrete. I would not have a problem if they ran it MC on a running board. Guess I'm getting paranoid in my old age

I may have a problem with aluminum wire used as a Ufer. I am not sure there is a concern about simply having aluminum against concrete. We have aluminum screen cages tapcon screwed to the slab and the block walls out in the weather. I have not seen any corrosion issues with them and that is here in monsoon country. I think I would be more concerned with steel straps on aluminum armor but that doesn't seem to be an issue.

I went back and looked at the references to concrete and aluminum. It says you can't pour the raceways in the concrete without supplimental protection and references "chlorides" that may be in the concrete <handbook note>. That is usually calcium chloride "heat" they put in to speed up the setting.

Here in mass we usually rum nm stapled to a running board. I see no problem with mc on the masonary but if your concerned shoot a board and then clamp the mc to the board. Can even sleeve romex thru emt with the changeover. The cheaper way out than useing mc.Mc can be for exposed work. I dont have a problem with what you are doing.

My feeling is that MC is subject to physical damage because of the aluminum casing. It could very easily be damaged. Certainly more subject to damage than EMT or RNC.

FWIW I get MC in aluminum, steel and lightweight steel.

It is not always aluminum.

NM cable is often run down basement walls on a running board so it is a tough sell IMO that MC is more likely to be physically damaged.

Personally I like EMT on minnis in damp basements.

Being the AHJ in my municipality here’s my slant on this one. I don’t have as much of a problem with the MC cable being mounted on a block wall as long as it is a dry location. We all have seen people use MC cable when they punch a hole through a block wall to feed a wall pack and usually it passes as long as it’s a dry location. Where I have a problem is with the physical protection. Surface mounting MC cable on a basement wall in a residential application is just asking for little Billy to come down and see how much damage he can reek on it while he’s playing alone down there. The point I’m trying to make if it’s okay to use it for a laundry circuit then you would also be saying it’s alright to use it for surface mounted wall plugs on a cement block basement wall and this I would have a problem with. Just my two cents worth. Hi George.

The only real issue I see is physical damage and that is a local call that varies widely across the country. Some AHJs see utility and basement areas as damage prone, others don't seem to. I tend to lean toward the "can be damaged" side.

Most MC is listed "wet location" these days.

Someone explain to me why it's not permitted to have aluminum wire in contact with masonry (250.64(A) but it's okay to have an aluminum jacketed MC cable in contact with masonry. Are the chemistry issues the same? It's okay to have copper in contact with masonry. I need to be educated here.

George IMO the difference is it's of less concern to have the armor get some corrosion than it is to have a conductor suffer corrosion.

I have nothing to back that up, it's just a guess.

The question of it being damaged is as Greg said a local call.

In my area almost every basement has NM running down the cellar walls into the panel and will have few NMs running all the way down on running boards to outlets.

This is how its done here, this is what passes inspection and yo know what....it works fine.

I don't see these getting damgaed very often.

Can they be damaged? Sure.

Do they often get damaged? No.

We also use SE for services and if any place little Johnny is going to swing a bat a cable it seems it would be outside.

It's just a local thing, you can bet if it was causing problems it would change.

I guess I'm not concerned about
Johnny's basebaall bat. I was thinking more about the corrosion. Guess I can sleep better now after reading "Uses Permitted" a little closer.