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I am replacing a 20 year old wall oven. When I opened the electrical box I noticed very large gauge aluminum wiring (6 gauge?). I purchased a box of AlumiConns (3 port style) to connect the aluminum wiring to the 10 gauge copper wire in my new oven.

Can I simply untwist a couple aluminum strands from the larger bundle? I plan to insert two aluminum strands into two ports on my AlumiConn and the 3rd port will go to the oven's copper wire.

Note in the 2nd photo below that there was no anti-corrosive paste inside the wire nuts. I was a little surprised how well this 20 year old connection stood the test of time, the wire nuts showed no sign of getting hot and the old copper and aluminum wire looked fresh. I'd still like to update the connection to current code and not have to worry about a future electrical fire decades from now.

Aluminum wire bundle Old oven connection aluminum bundle to oven's copper wire

  • While this isn't a dismissal of the risks, I've seen the same thing in joining aluminum and copper without paste and no evidence of corrosion (knock on wood). The real danger of such connections is that if they get warm the wires work loose and can cause an arcing situation. – Machavity Jan 30 at 3:51
  • Your right about arcing. I specifically looked to see if this 20 y/o connection showed signs of arcing but after unwrapping the electrical tape and untwisting all 3 nuts, I was surprised how fresh everything looked. I wonder if this was to code back in 1999/2000 (other than the missing nut to hold the armored cable from pulling out). – Julius Seizure Jan 31 at 19:10
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Use a mechanical lug connector ("Polaris" or equivalent)

AlumiConns are only rated for a maximum of 10AWG wire. For fatter work, you'll want their bigger brothers, mechanical lug connectors (sometimes called "Polaris connectors" after a common brand name) -- the smallest size of them is generally rated for wires anywhere from 14AWG to 4AWG, and as a rule, they are dual-rated for aluminum and copper wire.

You will also likely need a box extension ring or two, as mechanical lug connectors are quite chunky compared to wirenuts or Alumiconns, and you definitely need an appropriate connector to attach the flexible conduit to the box, as right now, it's violating several Code sections by flapping around in the breeze like that. If the extension rings aren't enough, then you'll have to replace the box with a small (6" by 6" by 4" should be ample) NEMA 1 (indoor) pull box, likely with a flush cover. These are what is used instead of a junction box when splicing large wires, and are available through electrical supply houses.

  • Your right that stuffing 3 Polaris connectors won't fit. What type of box would work, assuming no restrictions. The empty space both behind and to the side of the new oven is absolutely huge. – Julius Seizure Jan 31 at 19:15
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    @JuliusSeizure -- if you need to replace the box, use a 6x6x4 NEMA 1 pull box -- they're what's typically used when splicing larger wires. – ThreePhaseEel Jan 31 at 23:53
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No, it's illegal to split wires like that. Aside from failing on 110.12 neat and workmanlike, it is also paralleling (not allowed without special appartus) and 110.3b using a product inconsistent with it labeling/instructions.

You need a lug connector rated for #6. Loks like an Alumiconn but is rated for #6. This is readily available at any proper electrical supply, Home Depot won't have it of course.

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Alumicons are rated for

Aluminum Wire Range: Min #12 / Max #10

Copper Wire Range: Min #18 / Max #10

So your #6 Al wire is way over, not even close. One way to go would be Al-Cu split bolts, but making these up properly takes some skill. You may need a box extension for that box, too.

The flexible metallic conduit is not connected to the box properly. You need a connector fitting.

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