I recently purchased a home that has some aluminum wiring. The previous owner decided to "upgrade" the receptacles to make it "safer" for me and my family; these changes were made after the general inspection. He added some kind of crimp (yellow) between the wire and the receptacle and then added anti-oxidant paste.

I had two electricians inspect the work:

  • The first claimed that it doesn't follow regulations/standards, it was dangerous, and crimps used are not rated for receptacles (usually for electronics) and that there is even more of a chance it will come undone now. He recommended cutting them off and doing the connection directly to the receptacle with the anti-oxidant paste (as it was before)

  • The second claimed that it should be fine as long as the anti-oxidant paste was added

Find attached a picture illustrating the crimps (yellow) that was used in the installation (this is a sample the previous owner gave me, the real wiring in my wall is aluminum.

enter image description here

Now I am reaching out to the community to see who is right... Are these "crimps" safe and acceptable solutions for the receptacle wiring or do I need to re-install them?

Any advice would be much appreciated, mostly worried about safety and insurances. Thanks,

  • I could be wrong, but that wire looks red-brown leading me to think that it's copper wire and not Aluminium. Otherwise, I don't know about regulation but those connectors are just fine, provided that a good crimp is used to crimp to the wire. Keen to see what the electrical specialists think, I have also used them when need arose.
    – Hightower
    Jan 28 '15 at 20:56
  • 2
    @Hightower The OP states that this is an example and that the real wiring is indeed AL
    – Steven
    Jan 28 '15 at 20:56
  • Are the existing devices CO/ALR rated? Jan 29 '15 at 2:35
  • @ThreePhaseEel not that I am aware of - he used "COSSE FOURCHETTE" PN 12-10CAXCR/6/JAUNE bought from a local hardware store, he states they are made for aluminium.
    – Jonathan
    Jan 29 '15 at 13:32
  • @ThreePhaseEel just got back from the hardware store and it says "for COPPER use only"
    – Jonathan
    Jan 29 '15 at 17:34

First off, the first electrician is wrong in saying that the use of a crimp-type terminal in house wiring is categorically unsafe. Crimp-type terminals listed under UL 486A for use on solid wire of the given gauge are considered acceptable for use in building wiring, as per UL 486A section 1.1:

These requirements cover pressure wire connectors and soldering lugs for use with copper conductors according to the National Electrical Code, NFPA 70.

and NEC 110.14(A):

Terminals. Connection of conductors to terminal parts shall ensure a thoroughly good connection without damaging the conductors and shall be made by means of pressure connectors (including set-screw type), solder lugs, or splices to flexible leads. Connection by means of wire-binding screws or studs and nuts that have upturned lugs or the equivalent shall be permitted for 10 AWG or smaller conductors.

Terminals for more than one conductor and terminals used to connect aluminum shall be so identified.

However, I would be quite hesitant to call this specific application fully Code-conformant -- garden-variety listed crimp terminals are listed for use with copper wire only, and it would be unlikely that the previous homeowner had access to terminals identified for use with aluminum wiring.

EDIT based on updated info about the devices:

Since the existing devices are copper only, your options go as follows (in order of preference):

  1. Find an electrician in your area who is qualified on the Tyco/AMP COPALUM system for pigtailing copper to aluminum -- these have a long, successful field service history, but require a specially qualified electrician to install, and are rather expensive -- you might be able to get the seller to shell out for this, though...
  2. Use the AlumiConn connectors with a torque screwdriver for pigtailing. This is something that most electricians can do, or you can DIY if you know your way around electricity and have a torque screwdriver -- the AlumiConn must be torqued to spec to meet its UL listing.
  3. Replace all the devices with modern CO/ALR types. This is a last resort as CO/ALR device performance has been historically variable, unfortunately.
  • I would strongly doubt the crimps used are rated for aluminum, but then wouldn't applying the anti-oxidant paste solve the problem of compatibility?
    – Jonathan
    Jan 29 '15 at 3:58
  • @Jonathan -- not completely -- field anti-oxidant is highly variable in its application. PROPER pigtails or new CO/ALR devices are the solution to this problem. Jan 29 '15 at 4:51
  • what about AlumiConn Aluminum to Copper Lugs?
    – Jonathan
    Jan 29 '15 at 6:33
  • @Jonathan -- the AlumiConn devices are somewhat new-ish, but they have shown a good test and field history so far. They'd fall under "proper pigtailing" in my book, barring evidence to the contrary. Jan 29 '15 at 23:39

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