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As you can see from my post history, I am blessed with a lovely home with aluminum wiring. I am also taking steps on every project to review and mitigate the risks of aluminum wiring by using proper pigtails or Alumiconn connectors.

The authoritative references on aluminum wiring seem to have been written at least a decade ago. Have the risks from aluminum wiring been mitigated to any extent by high-efficiency fixtures and appliances becoming more common?

My thought process is that an LED fixture will generate the same light with significantly less draw. This reduced draw reduces the heating and expansion of the wiring. The expansion and contraction is what causes the separation in AL and CU/AL joins. That separation then induces the sparking that gets people hurt.

My question is entirely focused on theory rather than application. Even if modern loads actually reduce the risk, it is still imperative to use the correct connectors and strategies with AL wiring. Using proper solutions, such as crimp connectors, AFCI breakers, and proper boxing nearly eliminates the risk which is far better than any theoretical reduction.

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    Lower ampacity will reduce risks. I use aluminum on house feeders because they are usually much larger than the current draw where individual branch circuits are usually loaded to the max. For this same reason I only use copper on motor loads because I have seen two many wire failures with aluminum I believe because the in rush current is much higher even though it is for a short time. Using proper connectors like alumicon and reducing the ampacity can only help make it safer.
    – Ed Beal
    Commented Sep 25, 2017 at 15:28
  • What year was this house built? In about 1975 a better Al alloy came into use. My 1970 house is wired in aluminum except the a/c condensing unit which is NM 8/2 solid copper. After @Ed Beal 's comment I know why that one circuit is copper. Commented Sep 3, 2020 at 15:33
  • My 1970 house is almost certainly wired in the older AA-1350 and not the newer and better AA-8000. How would one tell which alloy is in a cable? Commented Sep 3, 2020 at 15:55
  • @JimStewart that might be best addressed as a new question. IIRC its stamped on the wire insulation.
    – Freiheit
    Commented Sep 3, 2020 at 17:13
  • The OP here is wondering how safe his aluminum wiring is. If someone could tell him how to determine the alloy of his wiring, it would be highly relevant to his question. Commented Sep 3, 2020 at 19:03

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Focus on what is known to work.

AFCI breakers

What are you concerned about? Fires. Why? Because temperature changes, plastic deformation, dissimilar metals corrosion, and oxidation are causing contact surface/pressure to be lost. How would that start a fire? Arcing.

AFCI breakers are uniquely good at catching that. They are usually easy to install.

If you have a main panel like a Pushmatic that does not support them, then install a subpanel and route your wiring to it. Possibly one on each side of the main panel so you don't have to extend wires very much.

And when an AFCI breaker trips, treat it seriously.

Metal boxes

Of course a contact can just overheat. But that is vanishingly unlikely to be a problem in a metal box, becuase the heat has to reach the metal box before it can reach the wood, and metal has such very good thermal conductivity that it will make the entire box warm, rather than a small part of the box hot enough to ignite anything. And of course if the box is grounded, the arcing will cause an AFCI trip.

I would also recommend metal box covers, same reason, if they're grounded.

But in the aluminum wiring age, metal boxes were pretty common. I would change out any plastic ones.

Between AFCI and metal boxes, I wouldn't even rush to do the Alumiconns and all that.

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  • As I stated, "My question is entirely focused on theory rather than application. Even if this does reduce the risk, it is still imperative to use the correct connectors and strategies with AL wiring. ". This answers outlines AFCI breakers and metal boxes as the correct solution, but it doesn't address the question I am actually asking.
    – Freiheit
    Commented Sep 25, 2017 at 17:15
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    Because those things moot your question. Ergo your question only has a scope of "if I don't have them" and I'm saying that is a null space, since getting them is a much higher priority. It's not like any of us own a testing lab, so the best we can do is arm-wave extrapolations from theory. Which will tend to be a bit "bull"ish... ... Commented Sep 25, 2017 at 17:52
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    Thats a hard truth to get whacked over the head with, but you are correct.
    – Freiheit
    Commented Sep 25, 2017 at 18:26
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    Actually in new construction Plastic or phenolic was more common In the 60’s and 70’s arc faults trip on a bad connection thus the name arc fault , they also will trip on a short to ground but if they are arcing enough to create heat they should trip at that point. Also 4 of the major panels of the day are no longer available Stab Lock, Zinsco, Murray and push lock or bulldog. The question was about if reducing power or increasing to high efficiency products would reduce the fire risk the answer is yes and when the new device is installed every MFG I have seen requires alumiconns.
    – Ed Beal
    Commented Sep 3, 2020 at 16:45
  • I had a string of recessed LED ceiling lights replacing a string of 8 incandescent fixtures. And even with 1A load, I still torched and burnt through a purple wire nut AND on a separate box of same circuit, an orange twist nut fell off of a 4-neutral twisted wires: it settle on floor of 1-gang box. In my case, it was caused by a MWCB (3+1 shared loads) being on same phase thus overloading neutral. Simple swapping wires at breaker panel (plus junction box cleanup) Commented Feb 22, 2023 at 17:06

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