Aluminum wire for panel good idea?

Discussion in 'Electrical Forum discussion & Blog' started by DIYorBust, Jun 24, 2020.

  1. DIYorBust

    DIYorBust Active Member

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    Mar 5, 2019
    Location:
    Long Island, New York
    I need to update the wiring for an electrical panel in an apartment, and would like to decide if I should use aluminum wire to serve the panel.

    The service should be 150amps. I'd estimate we need about 70 feet of cable back to the meter. The plan is to use MC cable. I can buy 100 feet of copper MC 1/0- 3 conductor cable plus bare copper ground for 890 at www.wireandcableyourway.com. Or I can buy 100 feet of aluminum MC 3/0-3 conductor cable plus ground for 371. Both appear to meet the ratings for 150 amp service. NM cable is not allowed due to code, and the electrician says it is more cost effective to use MC cable over EMT conduit. The branch circuits will all be copper and the installation will be done by a licensed pro.

    Is there any reason not to save the 500 bucks and go with aluminum MC? Thank you!
     
  2. Reach4

    Reach4 Well-Known Member

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    Sep 25, 2013
    Location:
    IL
    Aluminum has the advantage of being less likely to be stolen.

    I think you are talking about interior wiring.
     
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  4. DIYorBust

    DIYorBust Active Member

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    Yes, this would be aluminum MC cable within the interior of a building. The meter is indoors in a utility room, and the routing would be through walls and chases. I don't think theft would be an important factor in this decision. I'm primarily concerned about safety, performance, and longevity, but if there are other issues with this type of wiring, I'd be interested to hear about it.
     
  5. Bannerman

    Bannerman Well-Known Member

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    Mar 19, 2014
    Location:
    Ontario, Canada
    Aluminum wiring is commonly used in commercial applications for large conductors where copper will be cost prohibitive, but all terminations will require aluminum rated devices including breakers,

    Aluminum wiring for residential applications became common for only a few years in Ontario in the mid 1970s. I am now aware that insurance and mortgage providers now too often requires periodic Ontario Electrical Safety Authority inspections for residences where aluminum wiring is installed.

    Before commiting to aluminum, ensure availability of aluminum rated devices, and you may wish to also enquire with your insurance and mortgage providers. Even if you do not currently require a mortgage, it would be prudent to enquire in case you need to sell the building in the future.
     
  6. Stuff

    Stuff Well-Known Member

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    Mar 7, 2013
    Location:
    Pennsylvania
    Curious why the electrician isn't supplying the cable. Lots of times can get a cheaper rate through their supply house.

    Copper or aluminum doesn't make much difference. The bigger Al will be more difficult to install. Make sure the lugs on both ends are rated for it including the bigger size.

    If this is the service for a dwelling then you normally can go one size smaller gauge on the wires.
     
  7. wwhitney

    wwhitney Well-Known Member

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    Mar 17, 2019
    Location:
    Berkeley, CA
    Aluminum for feeders is very common and a fine choice. The only significant advantage to copper is the smaller diameter. Aluminum is lighter and cheaper for a given ampacity.

    If the feeder is carrying the full load of a single dwelling unit, then you are allowed to use a factor of 83% ampacity in sizing the wire. Which means you could typically use #1 Cu or #2/0 Al for a 150A service.

    The neutral conductor may be sized for the calculated load, as long as it is at least as large as minimum required EGC (#6 Cu or #4 Al for 150A). In lieu of doing a calculation, it is fairly common on 240/120V feeders to reduce the neutral by 2 sizes. But you will be limited by the configuration of commonly available MC cable.

    Cheers, Wayne
     
  8. wwhitney

    wwhitney Well-Known Member

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    Location:
    Berkeley, CA
    Sounds like you are talking about aluminum for multi-outlet branch circuit wiring. That was problematic in the 1970s and is generally not done anymore. The aluminum alloy used in electrical wiring has changed since then, which has reduced the termination problems seen in 70s era multi-outlet aluminum branch circuit wiring.

    Aluminum is still a viable choice for larger single outlet branch circuits, such as an electric range or dryer, just like it is for feeders. Larger receptacles are typically rated for terminating Al, although it needs to be verified. Direct wired appliances definitely need to be checked, some of they say to use Cu conductors only.

    Cheers, Wayne
     
  9. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Occupation:
    Retired Systems engineer for defense industry.
    Location:
    New England
    Interesting sidebar regarding aluminum. What you see in aluminum will have an oxide coating on it shortly after it is made unless you prevent oxygen from getting to the surface. Aluminum oxide, unlike ferrous oxide (common rust) is clear and structurally the same size as the underlying metallic material...ferrous oxide is larger, so flakes off, exposing more raw metal to rust. So, since aluminum oxide is an insulator, to work in an electrical circuit, you need the proper terminations, and they must be installed properly. Otherwise, the oxide layer will create what amounts to a resistance heater when current is flowing that can damage things, drop the voltage to the branch circuits, and in extreme cases, start a fire.

    Done right, it works. Done wrong, it could be very problematic.
     
  10. wwhitney

    wwhitney Well-Known Member

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    What you say is true, but in practice for mechanical connections all that means is (a) verify the lug is rated for Al and (b) tighten it to the specified torque.

    Cheers, Wayne
     
  11. DIYorBust

    DIYorBust Active Member

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    Location:
    Long Island, New York
    So googling this, it looks like some folks put an anti-oxidant lubricant on the terminals, is this appropriate/necessary?

    @Stuff Yes you would think the electrician would know and do all this stuff, but I'm not sure. He was hired by my GC, so I didn't pick him. He installed a 100 feet of copper 1/0 wire in another location and tried to charge me double the price I could buy it for on the internet. Ultimately when I showed him what it cost, he agreed to reduce the price. I don't know if he overpaid and took the hit, or if he just figured I wouldn't know the cost of wire and he could take advantage, but the job was big enough that it's possible he agreed to loose a few hundred bucks to avoid a conflict. At any rate, I'm now trying to make sure the job is priced properly for the next apartment. In theory he should bid the job and decide what to use and where to buy it, but these panels were an add-on to a bigger job, so we're trying work it out. But for a small add on, I don't really want to bid it out. He did the 1/0 cable job before he gave me a bid, or I even ok'd the work, so maybe that is why he backed off when I challenged the price. In general I like the guy and would try to give him the benefit of the doubt. But I am confused why he would use copper when aluminum could save money, both on the time and materials add on, and the original contract. For the contracted areas, it would be money in his pocket, so why not use aluminum? I don't know, he didn't really have a reason when I asked.
     
  12. wwhitney

    wwhitney Well-Known Member

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    Mar 17, 2019
    Location:
    Berkeley, CA
    Opinions differ.

    My attitude is that (1) if the manufacturer of the device (circuit breaker, main lugs in a panelboard, etc.) doesn't call for it in the installation instructions, it isn't required and (2) for the anti-oxidant to actually do any good, you have to apply it properly, which means getting it in between the strands of the wire, then wire brushing the wire through the anti-oxidant to remove the oxide coating, then applying more to be sure there's no exposed metal. Which is a lot of trouble if it isn't required.

    On the other hand, some feel that just squirting some in might do some good and won't hurt. And some inspectors have gotten the idea that it's required, which contractors will sometimes go along with as it's easier (if messier) to squirt some in than to educate the inspector.

    On the face of it, markup for materials is reasonable when the contractor is just charging for time on site, as the markup covers procurement time and costs, warranty support costs, etc. Double is pretty high but still (barely) reasonable.

    Aluminum got a bad rap from the problems with the 70's era multi-outlet branch circuits, and there's still an impression out there that copper is a higher quality choice, even thought that's mostly or entirely a myth. So some people just default to copper.

    Cheers, Wayne
     
  13. DIYorBust

    DIYorBust Active Member

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    Mar 5, 2019
    Location:
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    So interesting little update. I chatted with the electrician who said he was paying 20-30 bucks for a gfci outlet. I said I'm buying them on Amazon for 8 bucks for the levitons, if I buy a 3 or 4 pack. He didn't seem surprised, so I asked him to explain how this works. Well, it seems a big component of this supply business is credit. The supply house charges these high prices, but the tradesman doesn't pay until after the job is complete. However as the building owner, this is not a great deal so there is room to make a better deal buying materials directly, especially if the materials are expensive. You pros probably know this, but as a DIY it wasn't obvious to me.
     
  14. WorthFlorida

    WorthFlorida The wife is still training me.

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    Occupation:
    Retired
    Location:
    Orlando, Florida
    Up to a point buying items on line to save money, instead of your local supplier or contractor may pay off but when there is a problem, who do you call. Before Amazon was a one stop shopping for just about everything, I bought two $225 smart thermostat for about $180 each, if I recall correctly, off of eBay, new in box for the church I worked for. About a month later one of them went bad. The eBay seller bucked because we could not prove that it was installed correctly and Honeywell refused it since the seller was not an authorized seller. I was stuck and I had to buy a new one. This was six years ago.

    I've learned a long time ago, let the contractor buy the materials as he or she sees fit. A competent one wants a good relation, repeat business and generally know the best product for the job, they do not want to return to fix problems.
     
  15. DIYorBust

    DIYorBust Active Member

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    Mar 5, 2019
    Location:
    Long Island, New York
    Well with something like wire, if defective in some way, I think most online retailers would replace it. Or say pipes. If buying 100 feet of cast iron pipe, why pay double? I can just order it ahead, inspect it, and have it there when the plumber shows up. With a t-stat, this is a real headache for a contractor, who might have to go back three times to deal with the problem, but as a homeowner, if you buy a t-stat off amazon and it doesn't work, you can return it and just hook up the new one when it arrives. I recently saved about 500 bucks by ordering some thermostatic shower valves online instead of buying through a plumber. If they don't work, I'll have to deal with that, but I don't see it being a huge problem.
     
  16. hj

    hj Master Plumber

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    Aug 31, 2004
    Occupation:
    Plumber
    Location:
    Cave Creek, Arizona
    Evenif the customer supplied the material, I charged a "fee" for handling it, but did NOT give any warrantees for performance. If something went bad, and I had to do the replacement, they paid the labor to remove it and install the new item.
     
  17. DIYorBust

    DIYorBust Active Member

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    Mar 5, 2019
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    Long Island, New York
    I think we are working on different kinds of projects. These guys really don't give me a hard time about it.
     
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