What is the safest way to pigtail aluminum wiring?

Question

I'm looking for a way to remediate the aluminum wiring in a home built in the 1970s. Currently, the whole house is wired with aluminum and the switches/outlets are original and not aluminum rated.

After looking around online, I've seen three popular ways of dealing with this situation (besides rewiring the house):

Pigtail the fixtures/switches/receptacles with copper wire using AlumiConn connectors.
Pigtail the fixtures/switches/receptacles with copper wire using aluminum-rated wire nuts (purple).
Replace the existing switches and receptacles with aluminum-rated ones ("CO/ALR") and use solution 1 or 2 for everything that isn't a switch or a receptacle.

Everyone seems to have various opinions on which is the best way to do it. Most of the electricians I've talked to so far have claimed that #2 is the best way to do it, but without having a good reason why (other than "that's the way we typically do it").

Which is the best option, and why? Is it possible to mix those methods?

Think it comes down to a cost/benefit/labour. #2 is probably least cost and easy and does the same as #1 and #3. — crip659, Jan 19 '22 at 17:09
All 3 methods are considered safe and use UL approved methods. How do you define "safest"? — FreeMan, Jan 19 '22 at 17:14
The "best way to do it" is to use the method approved by your local code officer. — MonkeyZeus, Jan 19 '22 at 18:10

score 1 · Answer 1 · edited Jan 19 '22 at 17:38

The most likely reason for using method #2 the rated wing nut is:

lower cost
time and speed
use less space

Con

limited capacity (can't join multiple wires)
nut can only be used once
the twist can weaken the alu wire and retwisting will most likely break the end of the wire off and shorten the wire.

Method 1 - using the alumiConn

only choice if the Alu wire is short
easy to make a tight connection
handle multiple size wire and multiple wires (buy the size and ports needed)

Con

Takes up a lot space (in a tight box, difficult to fit them in
expensive and for larger size wire - multiple ports - Really Expensive

Yes - you can mix the three methods to fix any of the outlets that do not have aluminum-rated receptacles.

It would unusual to have none rated alu outlets and switches in a house wired with ALU wire unless the owner/tenents did replacements with improper receptacles.

If you are not pigtailing copper wire, then you need to replace the existing switches and receptacles with aluminum-rated ones ("CO/ALR").

For the outlets and switches you have pigtailed copper wire, then regular copper-rated receptacles can be used.

As others have recommended, always use the screw terminals and not the jab in the back. Alu wire always have to screwed on.

I use AlumiConns on the hot and neutral and a wire nut with antioxidant paste (Burndy Penetrox) on the ground. — Jim Stewart, Jan 19 '22 at 21:57

What is the safest way to pigtail aluminum wiring?

1 Answers1