Two quick panel questions

1: there are red “B2” wire nuts connecting copper and alum conductors inside the panel. The technical specs for these caps don’t say anything about aluminum, but it does say they have a deep well for “dielectric” purposes of some kind. I can also see what appears to be antioxidant grease inside the caps. Is that okay?

2: is this golden metal piece a retainer clip for this backed breaker?

Bonus points: see anything else?

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  1. I write up mixed wiring material spliced directly together like that.
  2. Yes.
  3. The Gieco Gecko.
  1. According to Ideal… NO!

Ideal B2

  1. Yes


Ideal/Buchanan B2 red wire nuts are NOT rated for CU/AL connections:

The only wire nuts that are UL listed and approved for CU/AL are the purple type 65’s.

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Thank you guys! May god’s blessings fall upon you.

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I don’t believe they are actually approved either… I remember reading somewhere that they somehow have an approval on their package that is not official.

I have seen the purple ones completely burnt to a crisp.

No wire nuts should be used for co/al, because they should not be twisted around each other, that is what causes the loose connection, and therefore the fires.

That’s why the alumicon connectors have individual screw connections, to keep them isolated from each other. Those, and copalum connectors are the only ones that are actually approved by NEC (I believe)



Daniel is correct about the only approved connectors.

Copper wires and aluminum wires cannot be connected but can be spliced. . Because the potentials of the two are different, the contact part will accelerate the oxidation of the aluminum wire due to the battery reaction, resulting in poor contact. Should be labeled, Aluminum to Copper Wire Connectors.

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Link below reads in part: ACS model for aluminum conductors. Approved for aluminum-to-aluminum, copper-to-copper, aluminum-to-copper (or highly stranded copper) connection. AWG wire range; 18-10 solid/stranded. Approved for circuits up to 600 V and lighting fixtures and signs to 1000 V.

IBERVILLE CONNECTOR ACS 65C-CDN | RONA-google--aw_smart_shopping_generic_allproducts-_-71700000066239895&gclid=Cj0KCQjw8_qRBhCXARIsAE2AtRYCQ9leWsgQFgemfZR6ZfYAUZxKQCX8sBqzkEFeROE0UWuesZIibagaAh2nEALw_wcB&gclsrc=aw.ds

Thanks for reminding me. I’ll just recommend they properly splice aluminum conductors.

So do you also call out those cu-Al wire nuts when you see them?

Although the CB is back-fed that is not your typical back-fed breaker. Back-fed breakers usually occupy two of the normal breaker slots. The 125 amp CB assembly shown is a main breaker kit that is used to convert a main lug only panel to a main breaker panel or as part of a main breaker panel.

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Riiiight, thank you Robert

I don’t know about that, Ideal is pretty specific about their UL listings, NEC compliance, and warns what they can and cannot be used for so the details are important. They are approved for CU/AL connections, they are NOT approved for AL/AL connections where the copalum connectors are the only ones approved.

From: Twister AlCu Wire Connector Model 65 Purple Card of 25

** Complies with N.E.C. Section #110-14(b) for aluminum-to-copper connections; UL Listed to 486C and CSA Certified to C22.2 #188*

The only twist-on for aluminum-to-copper connections.

The Twister® AL/CU Wire Connector is the only UL Listed aluminum-to-copper twist-on connector that prevents aluminum oxidation while providing a secure connection. Filled with an anti-oxidant compound, the Twister® AL/CU easily twists on with swept-wings making a comfortable connection with improved conductivity and cooler connections.

The live-action spring expands and contracts with aluminum wire to ensure a secure connection while the hexagonal head makes for quick and easy installation by hand or with a standard nut driver.

The Twister® AL/CU is the only twist-on wire connector to be UL Listed and CSA Certified for aluminum-to-copper connections, as well as the only twist-on solution to comply with the National Electric Code Section #110-14(b).

Twister® AL/CU Wire Connectors are designed as a one-use only connection.

For use only on copper-to-copper or aluminum-to-copper connections. Do not use on aluminum-to-aluminum connections.


Use only on Aluminum to Copper (Al/Cu) or Copper to Copper (Cu/Cu) wire combinations. When using with Al/Cu (intermixed – dry locations) combinations with Copper Clad Aluminum (CCA) conductors, the aluminum conductor can be replaced with the Copper Clad Aluminum substituted in the combinations listed above. One time use only. Do not reuse connector.