Is this the kind of situation where aluminium wiring is potentially dangerous?

Question

I recently moved into a rental that has aluminum wiring.  My understanding is that the wiring itself isn't dangerous, it's just the interface between aluminum and copper where you have problems because of the different behavior of the materials.
We did lose an entire "circuit" once and from what I gathered the issue was caused by a failure of a single outlet, likely due to the aluminum wiring.  I believe the fix was to add, in essence, a converter that safely goes from aluminum to copper so that you can install "normal" outlets.  The electrician suggested doing this throughout the house, but of course the home owner declined.
I since had a switch in a bathroom break (it physically broke - nothing related to an electrical problem).  I opened it up to see if I could replace it and found this:

AKA this is aluminum wiring going into what looks like an otherwise "standard" light switch.  It appears to have some goopy stuff on it for reasons that I don't understand.
The property manager will probably just send out an electrician.  Normally I'd do it myself because it will take an electrician a week to get out here (I've replaced outlets with copper wiring before), but with the unknowns introduced by the aluminum wiring I'm thinking of just leaving it to the professionals.
Is this safe and code compliant?  Is it probably unsafe but grandfathered in (until it needs replacement)?  Is there an easy way to make this safe while replacing the switch?

Harper - Reinstate Monica · Accepted Answer

Receps and switches labeled with CU-AL certification were legal at the time they were installed, but that certification later turned out to be wholly inadequate. They will be the source of trouble.
Receps and switches labeled "CO-ALR" certification are alright, as this is the revised standard that is much tougher on connector standards. Hint: the screws aren't brass.
You have to follow the instructions

NEC 110.3(B)  Installation and Use. Listed or labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling.

When CU-AL was decertified and CO-ALR was established, receptacle and switch makers who didn't step up to the CO-ALR standard had to make/label their devices for copper only.
Back in the day, sockets were either beige or black.  White is a fairly contemporary color, and I suspect it post-dates CO-ALR. Since they are not CO-ALR lugs, they are surely listed for copper-only.
It seems perfectly clear to me that you have an installer that just buys Cu-only devices and attaches them to aluminum anyway.  That is a codevio.
You're not allowed to fix it, though.
Almost any state or municipality has a rule that only licensed electricians can do electrical work on rental units.  Even the landlord can't work in an owned unit, because that would result in a sea of urban fires, as slumlords did cut-rate work.  No one can do electrical anywhere except a property owner who occupies the unit as their residence, or a licensed electrician.
There are exceptions but you have to ask the local AHJ what they will permit a tenant or landlord to do.  They often will waive the "electrician only" rule for simple recep or switch swaps.
Further, you need permission from the landlord to look at a cover screw cross-eyed. What you've already done would get you your walking papers with a lot of landlords; nobody needs a tenant who takes apart the building and does illegal work.

mark f · Answer

The goopy stuff is an Ant-oxidation coating required when using aluminum wiring.  If installed correctly, it should be safe... problem is many don't install in correctly and the joint between the copper/steel and aluminum can form a galvanic couple which can erode the connection and eventually open causing arc-faults. I don't think its allowed in new builds by code (except maybe special circumstance like RVs and mobile homes) [im not certain on this].
In short It is safe if installed correctly, but complicates simple fixes such as changing outlets and rewiring switches.  I would avoid it myself, and let the property manager bring in a pro.

JACK · Answer

Aluminum wire is generally safe if it's installed correctly. The goopy stuff in Noalox or something similar that reduced the oxidation of aluminum wire and is commonly used, it may even be required now. Any switches installed have to be rated for aluminum wire. There are wire nuts that are approved for copper to aluminum but they have been proved to be dangerous so stay away from them.
Since this is a rental, you should not do any electrical work in the unit, especially since aluminum wire is installed.

Machavity · Answer

The goopy stuff is called Noalox. It's the electrical equivalent of a band-aid, but NEC seems to buy it, since it's still sold in stores and you can buy purple wire nuts filled with the stuff.
There's two problems with aluminum branch wiring

It corrodes. Corroded aluminum is a fire risk. Copper contacting aluminum can corrode it faster. Noalox helps slow the corrosion
Copper and aluminum wires twisted and nutted together can get warm with use and work themselves out, posing an arc fault hazard (sparks and fire)

We did lose an entire "circuit" once and from what I gathered the issue was caused by a failure of a single outlet, likely due to the aluminum wiring. I believe the fix was to add, in essence, a converter that safely goes from aluminum to copper so that you can install "normal" outlets.

The preferred fix here is to install an Alumiconn splice, where you add copper wire to the circuit. It coats the wire in anti-oxidant gel (not Noalox) and keeps the wires separate (virtually no chance of of an arc fault). They're pricey, and electricians are pricier still. I'm not surprised the homeowner demurred on doing a full rework with them.
I wouldn't worry about the switch. The corrosion factor is fairly low and even lower with the Noalox on it. The reason they did that is you can't buy CO/ALR in anything except single/three/four way switches, and standard 15A outlets. If you want that kind of switch, you convert to copper (in this case, splicing all four wires separately) or you cheat with Noalox. Unless these switches are controlling some high-amp device, there's not much risk here of them working loose and arcing.
The greater risk is always some hidden junction box somewhere where some lazy electrician or even the homeowner just nutted aluminum and copper wires together. Anywhere you find copper wire, you might want to make sure they did a splice there and not a nut. Those are the kind that most commonly catch fire from what I've seen.

Is this the kind of situation where aluminium wiring is potentially dangerous?

4 Answers

You have to follow the instructions

You're not allowed to fix it, though.

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