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Can I use plumbers silicone grease as a substitute for silicone dielectric grease? They both appear to contain dimethypolysiloxane and silicone 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 plumbers 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 plumbers grease is called for, but going the other-way I'm curious if its suitable.

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  • That's... a really good question. I'm interested in the answer!
    – FreeMan
    Jul 21 '20 at 23:06
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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 '20 at 23:55
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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 '20 at 23:54
  • @fred_dot_u check out this response I got from a silicone manufacturer where they discuss the acetoxy vs methoxy formulations.
    – jxramos
    Jul 22 '20 at 0:53
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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 '20 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 '20 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 '20 at 17:31

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