AL MC Cable on a High Rise

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San -Brooke

San -Brooke

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About a year or so ago I watched a documentary series on NAT GEO about a High Rise being built in Los Angeles. They seperated the series by building trades, the episode about the electrical showed them using aluminum conductor MC type cable throughout the entire building even for receptacles and lighting. Is there something I am missing? Did we not see enough burnouts due to AL romex being used? Where exactly is this now a common practice?
 
I would be willing to bet all the MC smaller than 8AWG had copper conductors, it may well have an aluminum armor in all sizes.
 
iwire said:
I would be willing to bet all the MC smaller than 8AWG had copper conductors, it may well have an aluminum armor in all sizes.
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No it was AL for devices joints were made with CU pigtails.

330.104 Conductors.
Conductors shall be of copper, aluminum,
copper-clad aluminum, nickel or nickel-coated copper,
solid or stranded. The minimum conductor size shall be
18 AWG copper, nickel or nickel-coated copper, or 12 AWG
aluminum or copper-clad aluminum.
 
San -Brooke said:
No it was AL for devices joints were made with CU pigtails.

330.104 Conductors.
Conductors shall be of copper, aluminum,
copper-clad aluminum, nickel or nickel-coated copper,
solid or stranded. The minimum conductor size shall be
18 AWG copper, nickel or nickel-coated copper, or 12 AWG
aluminum or copper-clad aluminum.
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Well, can you find one American cable maker actually producing MC cable with aluminum circuit conductors smaller than 8?

I don't think there are any, in my area MC cable is king and I think if there was AL available I would be seeing it.
 
jim dungar said:
The 'old problems' were not with the conductor material. The problems were with terminations, particularly at devices.
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There were problems with the conductor itself, the terminations on the device and the workmanship. The aluminumin alloy used for the smaller conductors was changed in late 73 or early 74. At the same time the change was made in the conductor, the CO/ALR devices were introduced into the market.
There were few failures with the new stuff, but the history of the failures with the older products kept most from using the new products and the 15 and 20 amp sizes of aluminum conductors soon disappeared from the market.
 
don_resqcapt19 said:
There were problems with the .... the terminations on the device and the workmanship.
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Yes, conductor composition changes helped overcome the terminations and the workmanship issues.
I have never seen evidence of the original AL conductors failing 'in the middle of a run', at any rate greater than that of copper conductors.

Absolutely, the marketplace spelled the death of <#8AWG AL conductors.
 
jim dungar said:
I have never seen evidence of the original AL conductors failing 'in the middle of a run', at any rate greater than that of copper conductors.

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That is true...most electrical failures are at termination points and the combination of AL conductors and the steel screws on the wiring devices was a big issue. The CO/ALR devices had aluminum screws.
 
jim dungar said:
I have never seen evidence of the original AL conductors failing 'in the middle of a run', at any rate greater than that of copper conductors.
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Obviously you would with anything it is always going to be your weakest link electrically and even more so where exposure to open air creating corrosion with aluminum and also the galvanic action having an adverse effect on aluminum more than copper due to dissimilar metals and for that reason using aluminum IMHO is wreckless and irresponsible for branch circuit applications. From a life and property standpoint the option of allowing this type of installation in order to minimize costs should be removed from the equation with the NEC.
 
San -Brooke said:
Obviously you would with anything it is always going to be your weakest link electrically and even more so where exposure to open air creating corrosion with aluminum and also the galvanic action having an adverse effect on aluminum more than copper due to dissimilar metals and for that reason using aluminum IMHO is wreckless and irresponsible for branch circuit applications. From a life and property standpoint the option of allowing this type of installation in order to minimize costs should be removed from the equation with the NEC.
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There is no evidence that there are safety issues with the currently available aluminum conductors. As far as open air, the actual conductive part of most terminations is not exposed to open air. As far as galvanic action, that is based on how far apart the two metals are on the galvanic voltage table and the electrolyte that is available to complete the galvanic cell. The connectors and terminals that are listed as suitable for use with aluminum conductors will not have this problem.
 
San -Brooke said:
FYI Here is a link to the show http://channel.nationalgeographic.com/channel/content/lahardhats/timelapse/ however I cannot find an active video file that shows the episode where the in-wall rough in was being done. I could be wrong but I am alsmost positive they were using AL for branch circuits
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I don't watch a lot of these kinds of programs, but I do find it a little hard to believe they would cover the details to the point of telling us whether the conductors were copper or aluminum. I could see them mentioning that the wiring is an aluminum cable but even then they may only be referring to the aluminum sheath.
 
iwire said:
Well, can you find one American cable maker actually producing MC cable with aluminum circuit conductors smaller than 8?

I don't think there are any, in my area MC cable is king and I think if there was AL available I would be seeing it.
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Nobody is asking for it. If you place a big enough order they may likely make some for you.
 
kwired said:
I don't watch a lot of these kinds of programs, but I do find it a little hard to believe they would cover the details to the point of telling us whether the conductors were copper or aluminum. I could see them mentioning that the wiring is an aluminum cable but even then they may only be referring to the aluminum sheath.
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I never even got to see the whole episode. We had to go to the store or something prior to us having a DVR. But I do believe I remember a man explaining how he was making up joints for receptacle and switches. That is where I remember hearing about the aluminum for branch circuits.
 
Most of the AL failures I have seen were from improper installations, most of which were a #10 CU lugged under a 4/0 AL to run a well pump. I frequently went behind a local technical college teacher that was also a licensed electrical contractor in Georgia and North Carolina, and was notorious in doing that on mobile home services.
 
btharmy said:
It very well could have been MCAP. It was used here in Indy on the JW Mariott hotel. It has an oversized aluminum bonding wire for the egc. similar to the old ac.

http://www.southwire.com/commercial/MCAPandHCFMCAP.htm
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And if it was that bonding wire is for the bonding of each turn in the spiral sheath. You do not have to make any connections with the aluminum bonding wire at all. I have seen many cases where people have installed a cable (usually AC cable, but starting to see more MCAP so I may start seeing it with that) with such bonding wire and they make up this bond wire in junction boxes just like it were an EGC. Not necessary. They also make it up with connectors not designed for aluminum conductors. Problem is they don't really know what the thing is for, and probably have questioned themselves why the aluminum ground wire?
 
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