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Thread: Aluminum Wiring

  1. #1

    Question

    Is there any need to change aluminum wiring to copper? This unit has aluminum wiring from box to unit. Guess that's how they did it way back.

  2. #2
    Join Date
    Jun 2003
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    Florida
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    When in doubt....change it out. I change aluminum conductors whether they need it or not....some manufacturors specify copper only.
    If everything was always done "by the book"....the book would never change.

  3. #3
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    If there was ever a need for this reply

    Call a professional electrician.

  4. #4
    Properly sized aluminum to box is ok. Copper conductors to unit from disconnect is mandatory with every unit manufactured today.

  5. #5
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    I took a short cut once and used orig. alum. wire for new condensing unit that I installed. I was back out the fallowing year to find a melted disconnect and ended up pulling new copper anyway.
    Some people swear by me and some at me

  6. #6
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    Aluminum has a problem with "cold flowing" when under a mechanical screw connection. The aluminum gives under pressure and becomes loose. This eventually causes a loose connection which becomes a point of high resisistance and then heats up.

    Copper is much better under mechanical screw connections!

  7. #7
    Join Date
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    Originally posted by NormChris


    Aluminum has a problem with "cold flowing" when under a mechanical screw connection. The aluminum gives under pressure and becomes loose. This eventually causes a loose connection which becomes a point of high resisistance and then heats up.

    Copper is much better under mechanical screw connections!
    Fully agreed... I've seen more than 1 fire caused by this. IF you're going to keep the aluminum, make sure the connection is checked & lugs retorqued at the annual/semi-annual maintenance.

  8. #8
    Join Date
    Mar 2005
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    657
    I understand what your talking about with alum wire. But I thought it was ok if you used the black anti oxiding compound on the wire and made sure the connection was tight. I still see it used as underground feeders and overhead power lines.

  9. #9
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    It's not an oxidizing problem as much as an innate property of the metal itself. Aluminum has one of the higher thermal expansion coefficients out there of the metals. Copper has one of the smallest. So, as the Al wire heats up from the current, it'll expand and as it cools, it'll contract. This over time is what causes the wires to become loose in the lugs, and the subsequent overheating of the connection.

  10. #10
    Join Date
    Feb 2003
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    use devices rated for aluminum with aluminum wiring. the new outlets | recepticles do NOT need the paste per Levitron (for theirs).

    aluminum will cold flow when OVERTORQUED.

    do NOT retorque, because the threads have been deformed with the original installation, & probably have slightly corroded over the intervening time. This is true of ALL mechanical connections.

    aluminum is also nick prone = nick a wire = a possible break point.

    I use the 3M splicing sleeves with the copper insert for building wire sizes, red for # 12awg. Where moisture may be found, use antioxide paste with grit, eg: under dish washer.

    I have a cut- away of a pressure connector applied to a locomotive cable made of aluminum wire! AMP developed this connector for GE Locomotive Div.

    My house was wired with aluminum wire in 1974, some copper added later -- still in service! SE to range & split HVAC, hot water heater, 99% of outlets -- including in kit & bath, several 3-way switches -- not one had the copper/ alum rated devices! Yes, one was not working = screw had never been tightened. The circuit to the dish washer was bad, it had been under a water leak; has worked 5y since I reworked that junction with paste.

    Once again, follow the manufacturer's instructions!

    I was party to the aluminum building wire problem investigation in the early 1970s, while working at Anaconda Wire & Cable.
    harvest rainwater,make SHADE,R75/50/30= roof/wall/floor, use HVAC mastic,caulk all wall seams!

  11. #11
    Join Date
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    Alluminum is OK for 30 amps or higher as long as its stranded and sized properly. You do need anti-oxident on the lugs.

  12. #12
    Join Date
    May 2005
    Posts
    74
    Other than replacing with copper, the copalum method is the best. Specially trained electricians use a crimp tool that exerts a tremendous amount of force to pigtail a copper wire to the aluminum wire and seals it so that it cannot come loose. AL causes problems with its gets loose and arcing occurs. Google copalum and see if you can find an electrician near you that can do it.

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