I'm rewiring outlets and switches in our 1960's California home using AlumiConn connectors to connect the aluminum wiring to copper pigtails. Most cases are straightforward, but I've run into a case where a box (a double-sized box, thankfully) includes a joint of the neutrals of 4 aluminum wires (10 gauge each). AlumiConn's only come with a max of 3 ports.

What is the correct way to handle 4-wire connections? Is it correct to daisy chain the AlumiConns?

Lacking any other instructions, my instinct would be to wire them like this, but I don't know if this is acceptable, safe or correct:

  AL  AL      CU      AL     AL
  |    |   ,------.    |     |
  |    |   |      |    |     |
,--._,--._,--.   ,--._,--._,--.
|  AlumiConn |   |  AlumiConn |
`------------'   `------------'
  • Are there devices in this box, or is it merely serving as a splice point? Also, how deep is the box? – ThreePhaseEel Dec 11 '18 at 4:52
  • It's the box for a switch operating a switched outlet in the room. The box is extra wide behind the opening, so there is space for all the wiring. One of the wires must be incoming power, one must be going to the outlet, and the remaining two presumably go to another room. – mhucka Dec 11 '18 at 4:57
  • How deep is the box? – ThreePhaseEel Dec 11 '18 at 5:11
  • Is depth the concern, or overall size? Unfortunately I'm not there to measure the depth right now, but my impression was that it's basically the equivalent of 2 ordinary light switch boxes placed side by side, but with only one opening (if that makes sense). The material is not metal but some kind of hard plastic, dark brown or black in color. – mhucka Dec 11 '18 at 5:16
  • You are using a torque screwdriver on your AlumiConns so far, right? – ThreePhaseEel Dec 11 '18 at 5:20

You have two options here

You have two options here. Either you can daisy-chain AlumiConns as you describe, using 12AWG copper THHN for the jumper wire, or you can use a single Al/Cu rated mechanical tap connector (often called "Polaris connector") rated for the wire sizes in question (the smallest size you'll find can take anywhere from 14 to 4 AWG), provided the latter will fit into the box. An ILSCO PBTS-4-4, for instance, takes up about 2" by 1.3" by 1.4" (LxWxH) and requires a torque setting of 20 in-lbs for 14-10AWG wire. Either way, you'll need to torque these connections correctly, as you are already doing with your existing AlumiConns.

  • 2" x 1.4"? Holy cow. Now I understand that depth really is a concern :-). – mhucka Dec 11 '18 at 5:38

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