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Can I use plumber's silicone grease as a substitute for silicone dielectric grease? They both appear to contain dimethylpolysiloxane and silicon dioxide.

Is this the same product given different application names, one for plumbing, one for waterproofing electrical connections?

Danco waterproof grease, aka plumbers grease Permatex Dielectric Grease

The plumber's grease is food grade, so maybe that's the distinction:

The DANCO Waterproof Grease is designed for use as a lubricant for faucets and valve stems. It is NSF 61 approved and meets or exceeds the requirements of FDA regulation 21. This grease works well in temperatures between 0 - 400 degrees Fahrenheit.

https://www.jencowholesale.com/products/danco-waterproof-grease-lubricant-1oz-80360

And looking into NSF 61:

If you manufacture, sell or distribute water treatment or distribution products in North America, your products are required to comply with NSF/ANSI/CAN 61: Drinking Water System Components – Health Effects by most governmental agencies that regulate drinking water supplies

https://www.nsf.org/services/by-industry/water-wastewater/municipal-water-treatment/nsf-ansi-can-standard-61

Given the above it's probably not a good idea to use dielectric grease where plumber's grease is called for, but going the other way I'm curious if it's suitable.

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    Do they have the same viscosity? I don't know, but it wouldn't surprise me if the lubricant was thinner, allowing it to penetrate into joints better, and the one designed for electrical is thicker to stay in place better.
    – Nate S.
    Jul 21, 2020 at 23:55

4 Answers 4

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The wikipedia page makes some connections for us

https://en.wikipedia.org/wiki/Silicone_grease

Silicone greases are electrically insulating and are often applied to electrical connectors, particularly those containing rubber gaskets, as a means of sealing and protecting the connector. In this context they are often referred to as dielectric grease.

Special versions of silicone grease are also used widely by the plumbing industry in faucets and seals, as well as in dental equipment. These special versions are formulated using components not known to be an ingestion hazard.

One of the references on the wikipedia article states

Dielectric grease's base is usually silicone grease, which makes it waterproof and an effective barrier against moisture and salt precipitate.

3M seems to make a product called Silicone Paste, which is subtitled dielectric grease. They seem to emphasize the silicone aspect of it by listing 100% silicone lubricant, and later on in the applications section listing Dielectric grease for electronic equipment,...

That does seem to suggest an application oriented nature to dielectric grease, basically grease used for its dielectric properties.

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    You may very well be right and that one sold as a "plumber's" version could be used very effectively as an "electrician's" version. However, I think Ed nailed it when he noted that anything used in an electrical install must be UL listed (in the US, at least). If it's not, and the insurance company can prove it, they may deny a claim, and they have far more resources to tie it up in court than you or your customers. This very sad, unfortunate fact of modern life is, in itself, probably a good enough reason to have two different tubes in your toolbox. :(
    – FreeMan
    Jul 22, 2020 at 11:37
  • @FreeMan wow, I glossed over that when I read "needs to be listed", meaning shows up on the application list, rather that listed with the underwriters laboratory. Do people in the electrician trade speak of being listed as a shorthand for having the UL listing stamp on a product?
    – jxramos
    Jul 22, 2020 at 17:17
  • It appears to be that way, but since I only play "electrician" at home, I'll let one of the pros answer that for sure.
    – FreeMan
    Jul 22, 2020 at 17:31
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    It's only 2 years later, but I do believe that when an electrician says "listed" as Ed did in his answer, he means that it's UL listed for use in a code-compliant electrical installation.
    – FreeMan
    Jun 6, 2022 at 15:17
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If in a car or boat it’s probably fine but residential electrical anything you use needs to be listed. On my boat I fill but splices with RTV (silicone for mst people) this keeps the salt air out of the splice and they last as long as the wire vs nothing in the connection and they are corroded in 2-3 years.

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  • I've learned recently that some of the RTV mixes, specifically the ones that release acetic acid when curing, release acid when curing. The acid can be detrimental to the application, depending on the task, but not good for electronics. Newer formulations don't cure in the same manner.
    – fred_dot_u
    Jul 21, 2020 at 23:54
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    @fred_dot_u check out this response I got from a silicone manufacturer where they discuss the acetoxy vs methoxy formulations.
    – jxramos
    Jul 22, 2020 at 0:53
  • There is no such universal requirement for listing of "everything you use" in residental electrical installations. And any listing requirement would not apply to subsequent maintenance products used.
    – kreemoweet
    Aug 13, 2023 at 20:02
  • I would disagree @kreemoweet at least for the U.S. where almost all locations use the National electric code. The definitions labeled and or listed are required , there are some minor exceptions for tested equipment approved by the AHJ. If you want to try using non listed devices / products and a fire occurs especially if there is life or limb that was affected you can be held liable and insurance companies will spend a lot of $ trying to deflect liability. But I do this professionally and use listed products even something as simple as zip ties / tie wraps are required to be listed 334.3
    – Ed Beal
    Aug 24, 2023 at 16:23
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I would guess the key word here is “dielectric” which would imply high voltage flashover and other undesirable electric phenomena could come into play. This would probably not matter greatly in automotive wiring but could be problematic with house wiring, 120v and up. Going the other way, plumbers’ grease would have to meet health requirements due to the involvement of drinking water. So, no, I’d not recommend interchanging the two except maybe in the direst of situations. G

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I'm a Plumber and happened upon this thread, perhaps I can help, as I have used both of these thousands of times. Plumber's grease is usually of thin consistency and is usually in a remarkably larger can, perhaps the size of a snuff can sold as a substitute for cigarettes such as the capital of Denmark 🇩🇰, it also smells unpleasant and is opaque. Silicone grease is sold in much smaller cans, just a bit smaller than a half dollar piece and is clear colored, almost transparent. Plumber's grease will smell and be thinner consistency,. It's used to lubricate metal to metal surfaces like gate ball valves, especially where hot water runs through them over the standard temperature of a home water heater. Silicone grease is much thicker, and is used in faucets within structures where the water could be swallowed, houses, bathrooms in commercial buildings and certainly in dental offices. It's used for O-rings and gaskets to seal the water delivery off to prevent leaking and bleed over. It makes faucet handles feel smooth and NIT like even fine sandpaper. In my 20 years of doing service work, I may have gone through 20 to cans, because a very small amount goes a very long way. Imagine the size of a bb lubricating both faucets and with enough left for a cartridge in the kitchen sink also. I wish I also knew which to use on the cleaned AA terminal contacts inside a CD walkman. I've done much reading on this, and STILL don't know which to use. I think I'll just run to Ace and buy a tube of electronic terminal grease I'll use once.🙄🧐🤨😂 Have a good one, everybody. Signed,,, a great Dane

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