Joining allum nm to copper nm

Discussion in 'Electrical Forum discussion & Blog' started by toolaholic, Jun 6, 2012.

  1. toolaholic

    toolaholic General Contractor Carpenter

    Messages:
    874
    Location:
    Marin Co. Ca.
    Are crimp sleeves ok? Tanks Tool :confused:
  2. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,272
    Location:
    Cave Creek, Arizona
    s far as I know they are the ONLY approved method, IF they are the correct "crimp sleeves" not the ones you stick the wires in and then pinch with a "pliers type" tool. Expansion and contraction make wire nuts impractical.
  3. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,566
    Location:
    North Carolina
    When joining copper and aluminum conductors together the key is to keep them from contacting each other. Any device that allows them to touch each other is not a good idea and will result in a failed connection.
  4. ballvalve

    ballvalve General Engineering Contractor

    Messages:
    3,261
    Location:
    northfork, california
    How so when most all bus bars are al with copper wires in them?

    I would add some no-alox to the crimp too.
  5. Speedy Petey

    Speedy Petey Licensed Electrical Contractor

    Messages:
    1,006
    Location:
    NY State, USA
    "Crimps" are NOT an approved method. The ONLY approved method is an APPROVED method, such as a CopAlum splice or a specific CO/AL splice.
  6. toolaholic

    toolaholic General Contractor Carpenter

    Messages:
    874
    Location:
    Marin Co. Ca.
    Thank You one N all . I believe during the Nam war a lot of Allum. was used in Homes. Also copper covered Allum. It stinks to relocate a big sub panel with old Allum
    and New copper . Long hard day by My self.
  7. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,272
    Location:
    Cave Creek, Arizona
    The companies which make the Cu-Al "splices" call them "crimps" and use a "crimping tool" to secure them. Don't the aluminum bus bars have circuit breakers snapped on to them with the wire attaching to the breaker, not the bus bar?
  8. Speedy Petey

    Speedy Petey Licensed Electrical Contractor

    Messages:
    1,006
    Location:
    NY State, USA
    OK, but either way these are very, VERY, specific "crimps" designed for the job.
  9. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,566
    Location:
    North Carolina
    The crimp connectors as well as the twist on connectors that are marked cu/al have a very high failure rate. Those that use a screw to hold each wire are the best for the job at hand

    On a side note; the repair of aluminum is not a DIY project unless you have a desire to lose your home. I would not let a licensed electrical contractor work on my aluminum circuits unless he could show me paper work that he has been trained on the subject matter.
  10. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,272
    Location:
    Cave Creek, Arizona
    quote; OK, but either way these are very, VERY, specific "crimps" designed for the job.

    Which is WHY, I specified that they have to be the "correct crimp" devices, and use the specfic crimping tool for them, neither of which is "inexpensive". Those with a screw retainer in the side, CAN loosen because of expansion and contraction, the same as panel connections which use a "screw" to anchor the aluminum. Have you NEVER seen an aluminum power wire with the insultion melted back several inches from its anchor point because it has loosened and created resistance and thus heat? I have several times.
  11. toolaholic

    toolaholic General Contractor Carpenter

    Messages:
    874
    Location:
    Marin Co. Ca.
    Great info! Tanks Tool
  12. ballvalve

    ballvalve General Engineering Contractor

    Messages:
    3,261
    Location:
    northfork, california



    Most often - but more common is that those that are bright enough to use no-alox in the connection [speaking of larger feed wires] to stop the oxidation of aluminum, and then go back and re-torque. You can bust a nut tightening on a main AL wire and come back in a week and get an easy 3/4 turn. Then you have your neutral and ground bars that are aluminum with copper wires stuck in them. Interesting engineering. The latest GE panel I bought seems to have gone to a copper plated steel bar with a bit of "dip" in the under screw area to insure a good connection.
  13. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,272
    Location:
    Cave Creek, Arizona
    NO-ALox will do nothing to prevent expansion contraction movement or lossening.
  14. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,566
    Location:
    North Carolina
    Having worked with aluminum branch circuits for more than forty years I would consider myself somewhat versed on the subject. Over the years I have used every type of aluminum to copper conversion kit on the market and have had failures in all of them except one. The one in which I have never had a failure was with the ones with a set screw for each conductor.

    If one can get ¾ turn on a terminal one week after installation this says one thing, it was not properly installed the first time. In over 44 years of doing electrical installations I have yet to see an aluminum bus bar or terminal bar installed in any of the panels I have worked with. I have seen aluminum alloy but never aluminum.

    and in today’s market it does nothing for the conductor either.
  15. DonL

    DonL Jack of all trades Master of one

    Messages:
    4,517
    Location:
    Houston, TX
    The proper Crimps should change size with temperature as the material that they are made for.
    Using the wrong crimp tool is the mistake that many make. Crimp tools are calibrated for a reason.


    The set screw types and Torque wrench are safer if you do not have the proper calibrated crimp tool.
  16. Jim Port

    Jim Port Electrical Contractor

    Messages:
    156
    Location:
    Maryland
    The only approved crimp is the Cop-alum by Tyco. You need to be trained and lease the tool from Tyco.

    The Alumi-conn by King seems like a nice splice but calls for a torque screwdriver for proper application.
Similar Threads: Joining allum
Forum Title Date
Electrical Forum discussion & Blog Joining solid and stranded wires Feb 21, 2008

Share This Page