I've googled this already and found many people saying that Noalox is only for copper to aluminum connections. I know that Noalox stands for "no aluminium oxidation" but brand names often change meaning from their origins over time. I've also seen people claiming their bottle says it is only for aluminum to copper, while other people say their bottle also says it can be used for copper to copper.

Well, my bottle doesn't say anything about aluminium or copper - it just says it can be used for improving and protecting electrical connections.

Since I am replacing some outdoor outlets and switches that are about 20 years old and mostly rusted to hell, I thought it might be a good idea to put some conductive grease on the contacts for longevity's sake. (I am already replacing all outdoor wingnuts with weatherproof wingnuts which I think also have some kind of grease inside).

It seems Noalox is the only thing my local Home Depot carries for this purpose (or the employee is ill informed) and I'm on a tight schedule so I can't wait for something like Penetrox E-8 to arrive. I know there are concerns about Noalox actually potentially reducing connectivity, but my main concerns is simply ambient humidity and condensation causing corrosion in the contacts over time.

My feeling is that Noalox will do a decent job in this regard, and so even if there is a 1-5% cost in connectivity, there is a 100% improvement in anti-corrosive longevity. Am I wrong? Anyone else care to weigh in?

A related side question: is it a crazy idea to use dielectric grease on the prongs of an outdoor device that is essentially permanently installed and will be plugged into an outdoor receptacle, potentially for years on end? Or is there a better grease for this? Or better nothing at all?

I know there are concerns about non-conductive grease in high voltage applications since they might actually reduce conductivity, but considering most devices are designed for 110V and my mains is actually more like 124V, I don't see that being a huge issue. Especially since these outdoor devices aren't high amperage.

  • Most devices are designed for 125V. Mains voltage hasn't been 110 since the war. When power was first marketed to the masses, it was 110V, and naturally, that stuck the way "Xerox" stuck. Dec 4, 2018 at 3:36
  • Um, most devices are designed for international use, and 125V is not standard the world over (or even where it is, it's not always dependable). Almost every device I've seen is labeled as 110V - 125V, and sometimes only as 110V. And most devices are built with even more tolerance than the label indicates. Similarly, the other main standard is 220V which actually varies in practice from 220V - 240V+.
    – Daniel
    Dec 4, 2018 at 4:12
  • I am discussing the context of your question, which is the I Dec 4, 2018 at 4:21
  • My point is I'd expect 110V would be well within the design specs / tolerances of any modern device, and I'm doubting that dielectric grease would affect the conductivity by that much. I could be wrong about the effect of the grease - I very much doubt I am wrong about acceptable voltage ranges on any given mainstream electrical device. Mains being reliably 125V in America is pretty irrelevant considering the vast majority of electronic components are built in China for a global market, and even American- or European-built devices will also be aiming for global distribution 9 times of 10.
    – Daniel
    Dec 4, 2018 at 4:25
  • I'm just trying to say voltage is supposed to be 120V not 110V, so it's only 4V out of spec. Sockets and the like are rated 125V. Electrical gear that is installed in buildings like panels and sockets are made exclusively for the NA market by reputable firms like Leviton and Eaton, often built in China but strictly to American spec. That sea of junk from Alibaba/express/ebay/Amazon fleaMarketplace is not permitted in building wiring because it's not UL listed. Dec 4, 2018 at 4:54

2 Answers 2


I have used dielectric grease for years in so many applications. For mains voltages is is primarily a non-conductive corrosion barrier. In that sense, any non-conductive grease will do. Electrically, the original metal-to-metal connection is maintained because corrosion is reduced. You can use it liberally around connection points because it does not conduct.
Noalox sems to contain zinc dust in a plastic grease matrix. I'm not sure how conductive it may be at mains voltages, but I would apply it only at the specific connections.


Putting aluminum wire on copper terminations is a bad idea, it's what started all the Al hubballoo in the furst place. That is why large lugs are aluminum. Noalox is also for aluminum-aluminum bonding. It will work fine for Cu-Cu. Also, aluminum wireneuts are rubbish.

You are talking about receptacles that cost 75 cents and wirenuts that cost 3 cents, It isn't worth going to extremes to protect outdoor electrical gear from damage, because that's gonna happen.

Related, you really want to arrange your wiring so your GFCI protective devices are indoors. You wouldn't leave a phone outdoors and expect it to work for long, don't do that for any other electronic device...

  • 1
    The home is too old and jury-rigged for it to be worth my time to figure out where the wires go and what else is on the circuit and how it is wired. I'm looking to do the best job I can within the limited scope of the assignment. The rest of the circuit can fail for all I care, but the parts that I touch specifically I want to be installed correctly and as reliable for as long as possible. I don't like to get calls later, even years later, for something I should have done right the first time.
    – Daniel
    Dec 4, 2018 at 4:09

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