Jeff Eastman

[Jeff Eastman]

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[Thom Walker]

Jeff,
Do you have other pictures of the panel?

[Jerry Peck]

It's wrong (unless that wire nut is rated for both copper and aluminum).

But not any more wrong than that low voltage in there (which I'm sure you wrote up).

[Rick Cantrell]

Low voltage wires/cables are not permitted to be in the same box, conduit or raceway as house wiring.
First of all it's a safety issue, next the low voltage lines can, will and do pick up induction interference from the higher voltage ac lines, causing a lot of problems with low voltage equipment.

[Jim Luttrall]

Jeff, the low voltage cables could become energized by the high voltage cables, kind of like water and electricity, they are best kept separated.

Aluminum and copper connections are not allowed since the two dissimilar metals react and corrode which causes poor connections and overheating. The two metals must be connected through an approved method which keeps them apart. A twisted connection with a wire nut of any kind is not acceptable.

[Bruce Breedlove]

Aluminum has a higher coefficient of expansion than copper. When an aluminum wire is heated (e.g., by current flowing through the wire) it will expand more than the same sized copper wire. When aluminum and copper wires are connected together this difference in expansion can cause the connection to become loose. A loose connection can cause arcing. Arcing can cause a fire.

Common wire nuts are not designed to accomodate the different expansion rates of aluminum and copper. Special wire nuts and connectors are available for aluminum-copper connections and are usually purple in color.