Several years ago when I was browsing at Home Base I ran across some electrical wire that was basically the equivalent of 3 conductor romex encased inside of a solid metal tubing that could be flexed. The overall package appeared to be a great alternative to using metal conduit with wire added inside for surface mounted applications. I have not seen the stuff since I and I don’t have a clue as to if it is even still available. Does anyone know? If still available is it code approved as an alternative to metal conduit with wire fished through it?
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It is called mc cable (metal clad cable)
Sounds like you're talking about armored cable, though I've heard it called other things. Pretty common. Any electrical supply store should have it.
Just a quick check, since I have a catalog here, McMaster carries it anywhere from 14-2 up to 10-4 wire. http://www.mcmaster.com. Look locally though, S&H will eat you alive on this stuff.
I checked the catalog at McMaster-Carr and the products they show while indeed clad with metal are not what I saw before. The ones shown in the catalog have a metal shield that is spiral wrapped around the wire. I have seen this type locally too. The metal shield on the wire I saw was essentially solid tubing with the wire inside of it. There was no spiral wrapping and the outside could easily be mistaken for tubing used for plumbing if you didn't see that there was wire and insulation inside. There were no ridges either. The metal used may have been aluminum and was at least silvery in color.
You probably saw a waterproof variety of armored cable. It has a plastic coating of some type on the outside. Again, should be available at an electrical supply store. With the right fittings it's totally waterproof. Some types can be buried. Last time I bought some, 1"ID was about $1.50/ft. Connectors were about $5 ea..
We use it on some of our equipment here. Particularly on the larger sizes it looks smooth, though inside the metal is spiral wrapped cable the same as normal armored cable.
Thanks for all the resposes...
That's still not what I saw. There was no plastic coating. It was bare metal on the outside and definitely no spiral wrapping. It was also relatively small in diameter - something like 1/2" OD. I believe the stuff that I saw was 12 gauge 3 conductor.
I don't get it. It must have come in a coil, right? So if it is a smooth metal sheathing on the outside, how do they coil and uncoil it? Do you mean it was like soft copper tubings except it was silver?
Tom
Yes - that is exactly what I mean. It did come coiled up.
I have only seen what I think your describing a once. I have seen a few rolls of the stuff. Surprisingly it was for sale at a K-Mart so it stuck in my mind.
First a description of what I saw so that we are sure I'm barking up the right tree. A cable, multiple conductors in a single assembly, surrounded, fairly tightly, by what I took to be an aluminum sheath that was flexible, easy to bend by hand, and smooth in texture. The assembly was about 1/2" in diameter and containing three insulated #12 copper conductors (Black, white and green.) within a paper wrapping that separated the conductors from the outer aluminum sheath.
This is a rare, at least around here, form of MC, metal-clad Cable described in article 330 of the 2002 NEC. I have never seen this stuff used in this area and seeing it has been a rather singular event. It can be used, according to the NEC, just about anywhere except buried, encased in concrete or where exposed to corrosive agents. Generally anywhere you can use EMT you can use MC. With the provision that the AHJ, Authority Having Jurisdiction, makes the final call. Check with your local building department.
As far as I can tell the normal corrugated version of MC has all of the advantages, and weaknesses, of the smooth version. This stuff, the normal corrugated version, is widely available at any of the big boxes and electrical supply houses. The later might be able to track down the smooth version if your heart is set on it. Check with the AHJ before ordering. MC is quick, just a bit slower than NM, Romex, to install. The metal sheath provides some protection but, as with any cable, once installed you cannot pull in new conductors like you can with a conduit system.
Section 330 refers to MI [Mineral Insulated] cable.
Perhaps this stuff is Flexible Metalic Tubing -- Section 349?
MI cable is interesting since it doesn't use plastics for insulation at all. Thus it can withstand very high heat. I've never seen it but would like to. The insulation is highly compressed Magnesium Oxide.
FMT is actually just a tubing so I guess it's not really it. The Handbook says it can be used in "ducts, plenums and other air-handling spaces".
There is also Nonmetalic Underground Conduit with Conductors [Section 343] but again this is made of plastic instead of metal. It can't be used indoors. You can change the conductors tho.
I'm sorry this response is rather lame but it piqued my interest and I thought I had recalled some other possibilities [FMT + NUCwC] but they didn't pan out after all.
~Peter
I only have the 1993 and 2002 NEC close at hand. In the 93 you are correct 330 refers to MI and 334 covers MC. On the other hand in the 2002 NEC 330 is MC and 332 MI. I'm not sure what year it changed, I think it was in its latest revision, but in the current code, 2002, Article 330 does, in deed, refer to MC.
I'm pretty sure that this is MC as I vaguely remember seeing markings on the stuff I saw and nothing else fits the description. From the 2002 NEC Article 330, Section III- Construction Specifications:
"330.116 Sheath. The metallic covering shall be one of the following types: smooth metallic sheath, corrugated metallic sheath, interlocking metal tape. The metallic sheath shall be continuous and close fitting."
FMT, Article 360 in the 2002 NEC, doesn't fit the description in Malconium's original post, 29802.1 .
" Several years ago when I was browsing at Home Base I ran across some electrical wire that was basically the equivalent of 3 conductor romex encased inside of a solid metal tubing that could be flexed."
He seems to be describing a cable system, preloaded with conductors and installed as an assembly, not a raceway system, needing to have conductors pulled in after the conduit system, raceway, is complete.
You might want to buy a newer copy of the NEC. $60 at the local bookstore you can often get better deals at an electrical supply house. Got my last two copies, one for the house and one for the truck, for about $35 each at a supply house I frequent so substantial discounts might be available. Don't throw out the old copy as they are valuable references when a house is "grandfathered" in and repairs have to be made.
FWIW in the change from 1999 to 2002 there where some major changes in reordering sections of the code and changing a lot of the section numbers.
<an aluminum sheath that was flexible>
We see that product in Canada, and it's called Alusheath. Although I see it now and again on old installations I don't think it is still available.
Last week I ran into a bunch of it on a commercial reno, the conductors had a cloth covering on it which had deteriorated badly and the customer agreed it was time to replace it.
bake