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:

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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?

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    Somebody also mangled those screws - using a Phillips bit on a drill I'm guessing? I like power tools as much as anyone, but this is one kind of task I'd only use a manual screwdriver for. They're pretty short screws, and hand-tight is generally good enough for this application. Sep 18, 2020 at 16:57
  • @DarrelHoffman you should give lectures to the guys at Valvoline. Pretty sure they use one of these to reinstall the oil drain plug: northerntool.com/shop/tools/product_200658736_200658736
    – Z4-tier
    Sep 19, 2020 at 3:40
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    That grease looks just like Burndy Penetrox which is a first rate antioxidant grease for electrical connections. Do not attempt to improve these connections yourself. I do these connections differently in my own home, but a renter should not work on the wiring, Sep 19, 2020 at 3:46

4 Answers 4


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.

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    If it makes you feel any better, I definitely know better than to modify houses I don't own (especially electrical systems). I sent a picture of the broken switch to the Landlord and he asked me to remove the plate and get a picture so we could figure out for sure if it was aluminum, and if an electrician is required. It sounds like the only thing "missed" is that an electrician is required regardless, but that's fine because at the moment that is the plan.
    – conman
    Sep 17, 2020 at 19:08
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    Good point on the "CO/ALR" +1
    – JACK
    Sep 17, 2020 at 19:16
  • People don't understand that aluminum isn't as bad as it is labeled. If the right connectors are in place I have seen little to no issues. If the wrong connectors are in place (regular outlets) I have seen firework shows when plugging in a compressor... On landlords... trust me they have the worst "licensed" electrician on their speed dial that charges $25 an hour...
    – DMoore
    Sep 18, 2020 at 4:03
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    It may be worth considering advising the landlord's insurer, if there's any way to find out who that is. If the landlord has represented that wiring is up to standard, of even if they've neglected to mention Aluminum wiring, the insurer may consider it pretty serious. Big caveat: landlord's response may be to kick everyone out for "major renovations", after which rents might be raised, depending on local rules.
    – CCTO
    Sep 18, 2020 at 17:26
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    @CCTO that's also why not to take it to the city... the city's only real option short of some elbow-nudging is to condemn the property as uninhabitable, and then you're out. Sep 18, 2020 at 17:46

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.

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    Exactly. Aside from evicting you, the landlord could come after you to remedy everything that's out of code in the place... who's gonna believe you when you say "um, it was already that way"? Sep 17, 2020 at 19:30

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.

  • Okay, so definitely don't try to just drop in a new switch myself. Is there something out there that can safely "convert" from aluminum to copper so that I can install a switch normally?
    – conman
    Sep 17, 2020 at 19:01
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    That's not the cause. It's thermal expansion of the lug vs the wire. Al lugs on Cu wire are well-behaved; Cu lugs on Al wire cause plastic deformation of the aluminum wire (meaning it does not bounce back), causing changes in wire thickness, and thus, screw clamping force. Torques are pretty important, that's why NEC 2017 requires a torque screwdriver (on everything). Slapping no-alox on there is what people do to "cheat", rationalizing that the no-alox will make it OK. It won't. Sep 17, 2020 at 19:05
  • Thanks Harper, I had thought they "loosen" due to some kind of chemical effect rather and a thermal mechanical effect. Is Al wiring allowed on any applications in 2017 and newer code (other than service entrances)?
    – mark f
    Sep 17, 2020 at 19:12
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    @markf Absolutely. You can use aluminum anywhere you want. We recommend you consider it for any feeder #6 or larger. I would not use it for <40A branch circuits but not due to safety... only because when you sell, the home inspector/buyer will HATE it. You need AA-8000 wire and Al-rated terminations. OP's problem is that things like duplex switches and GFCIs, are often unobtanium in CO-ALR. So you wind up with 7 Alumiconns in the box, good luck on box fill with that! Sep 17, 2020 at 19:19

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

  1. It corrodes. Corroded aluminum is a fire risk. Copper contacting aluminum can corrode it faster. Noalox helps slow the corrosion
  2. 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.

  • This sounds familiar... I lost all electricity to the basement and the second electrician eventually found a junction box where the connections inside had somehow "fried". He did some things and power was restored. Yeah! It sounds though like your last paragraph was probably what was happening here...
    – conman
    Sep 24, 2020 at 12:17

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