Dielectric Grease

oldjohnt · July 8, 2015

Knowing that "Dielectric" Grease is an insulator, it was always my practice NOT to coat wires with "Dielectric" grease prior to splicing them. (I used it on spark plug wire boots so they didn't stick to the plugs) It seemed to me one would NOT want any insulation on the wires or between them, but instead pure metal to metal contact not encumbered by a coat of insulation. I preferred wires I intend to splice be clean, bright, shiny and dry, then make my splice AND ONLY AFTER coat and seal with material like silicone or tape or liquid tape or other sorts of sealants. My thinking was that if I kept moisture and oxygen off the splice, such would prevent "oxidation" corrosion and rust etc.

Then a buddy sends me this URL Link that indicates "Dielectric" grease is to be used different then my method HMMMMMMMMM

http://appliantology.org/blog/1/entry-848-dielectric-grease-myths-and-reality/

I'm sure folks including yours truly can testify "I used (or did NOT use) Dielectric grease or Silicone or tape or liquid tape or spray coating sealant on and on and on whatever" for years and never had a problem.

I'm still hesitant to coat the wires with an insulator prior to splicing and like my method which has served me well for years, but the article I linked indicates I may have been wrong. If so, its NOT the first nor will it be the last lol

John T

RV fan · July 8, 2015

John,

It has been my experience that dielectric grease will not totally insulate a connection where you have a sliding contact such as a push on connector and the connection will sometimes work. The sliding action will sometimes wipe the grease away and allow contact and provide some moisture protection. Splicing a wire with no sliding action would be a no-no for me. I once fell for the hype of using dielectric grease on battery post terminals, greased them, twisted them on (sliding action) with a few good cranks and tightened the clamps and wondered why my vehicle would not start. Back to the battery, remove terminals, clean off all dielectric grease and reconnect the terminals dry, ZOOOM she starts right up. So now I will sometimes lightly grease sliding connections (depends on the device) but not stationary ones. If in a harsh or wet environment the stationary connections get some after the connection is made as noted in the battery terminal example. On battery terminals I just use regular chassis grease and have now for years. I also use Corrosion-X for electrical areas needing some lube/moisture protection such as switches, circuit boards etc. I also use dielectric grease on some rubber seals and O-rings as I feel appropriate. You can't believe everything you read, maybe this reply is no exception but that's my story and I'm stickin' to it.

Good luck,

Jack Mayer · July 8, 2015

John, years ago I believed as you do. I then had an "interesting" conversation with someone I respected that worked in the marine industry. He had the same advice as the article you quote.

So, I set up a little experiment. I cut and spliced 10 sets of wires with and without dielectric grease. From 18 gauge to #10. I tested with a Fluke. There was NO - as in ZERO - difference in the electrical characteristics of the sets of wire. Not very scientific, but good enough for me.

I now use a light coating of dielectric grease on almost all my wire crimps. It has to help with corrosion. Although I can not prove it.

oldjohnt · July 8, 2015

This is just one of those things that just sounds so counterintuitive to an engineer.

"If you want the lowest resistance connection, coat the wire with this insulation first before you splice it" REALLY ????

Of course, the advantage is the insulation (a dielectric is a NON conductor, an insulator) you coat the wires with has other additional physical properties such that over time the reduction of oxygen and moisture outweighs initial harm IF ANY EVEN EXISTS THAT IS.

NOTE, I'm NOT arguing or saying the article is wrong mind you, however, I have no plans to run out and undo all my splices and coat the wires with a dielectric. I place my sealant on AFTER the splice is completed.

John T

skp51443 · July 8, 2015

We'd happily sit around mixing/mashing carbon granules into our dielectric grease back on my Army days. Made more of a mess than just grease, never saw any other difference other than getting yelled at if the grease wasn't black and gritty.

budeneighe · July 8, 2015

Youtube has a lot of examples and tests of Dielectric grease and vaseline and their resistance impact on electrical connections:

A newer one is:

More important is the summary stats at the end of this last video. Essentially no difference between vaseline and dielectric grease.

However, vaseline can explode. Dielectric grease can't. There is also a lot of variance between different brands of dielectric grease, too. Most just say flashpoint >200 or >300 Whereas vaseline and chassis lube have a specific flashpoint for brand and usually upper 380 - 400 degrees f.

Most important is that no connection depends on what it is coated in to provide any of the conductivity in the junction. That is purely by mechanical contact between the surfaces. Ever solder does not play a role in the conductivity of a properly soldered connection. It is only there to provide mechanical stability and protection from oxidation of the surfaces. If is doing more than that then it is a bad solder joint.

Lacking a protective layer of solder, plugged electrical connections are still vulnerable to oxidation and corrosion. Dielectric grease, when properly applied, should protect all micro surfaces that are not already directly protected by metal-to-metal surface contact.

In a pinch, vaseline or other heavy greases may also work but because they are petroleum based they are not pure substances and do contain their own amounts of potential reactive and organic contaminants which, over time, could contaminate the metals directly.

Kirk W · July 10, 2015

John, I was rather like Jack on that until I bought a home in the country that was a double wide which was built during the period of using aluminum wire in many such homes. I did a major remodel of that home and began to replace that aluminum wire with copper in all of the master bedroom & bath. In the process I took all of the cheap paneling down, beefed up the structural members and added insulation, before putting up sheet-rock. Part way through the project a friend who was a licensed electrician working a lot of remodel projects happened to drop by and while he approved of the wire changes he then told me that there is a quick and easy way to solve that problem in all of the other electrical connections for the remaining aluminum wire which will work and meed the current electrical codes. What he advised me was to go into each of the outlets and switch boxes, cut off part of the wire and crimp on a short copper wire, using dielectric grease in the crimp connectors such that pushing the wire in will force excess grease out. He explained that the problem with aluminum is that it will corrode from exposure to air and when it does that increases the resistance of the connection, which then causes heat that increases the rate of cording which makes it get even worse and sometimes can cause a fire.

The reason to use dielectric grease rather than some other product is not that it does conduct, but it is the fact that should it migrate where you do not want conductivity, it will not cause any problems there.

oldjohnt · July 11, 2015

Kirk, I'm just NOT a fan of aluminum wire use, I've seen too much go bad due to improper torque or failure to maintain proper torque in connectors or failure to correctly use anti oxidant grease designed for aluminum wire, where copper wire is more forgiving. Its (aluminum) used some here, more for service entrance, but that's usually installed by trained professional utility providers instead of the homeowner or a questionable contractor. Dielectric grease is an approved compound but counterintuitive to all I was taught due to the fact its an insulator NOT a conductor. I don't plan to re do every splice I've ever made in order to use dielectric grease, but I sealed them all AFTER secured (with silicone or dielectric grease or tape or liquid tape etc) in order to keep oxygen and moisture off to preserve the splice and material integrity. So far no problems, but I'm sure others who used dielectric grease can say the same lol After studying it more now, I may consider its use in the future. To each their own is fine with me.

Take care there in Texas, I will be passing through there this October in the RV enroute from the sons in San Diego to the daughter in Austin

John T

Kirk W · July 11, 2015

I'm no fan of aluminum wire either and I don't believe that it meets code standards for home wiring use today either. But it was a good fix for some people who had an entire house full of aluminum, as many were if built in the period that industry was using it. Today if you look at the main supply lines into most buildings from the supply to the main distribution box, most of that today is of aluminum, probably because of the cost difference. I have been involved in installing 200A service into a community center and three homes in the past two years or so and in every case the supply wire was purchased from our local electric co-op and it was aluminum. We did use a dielectric grease on all connections at both the meter box and the distribution box, but I saw nothing requiring us to do so from Wood County Electric, our supplier. All interior wire is of copper in each of these cases.

If you will pass through on I-20, drop me a shout and we will do coffee or lunch or something.

mscans · July 11, 2015

I have used a SILVER filled grease for this application many times with good luck but this product was DESIGNED for electrical conductive applications. Me . . . metal to metal with no insulators between just makes sense.

PS many years experience as an electrical design/process engineer but that's just me! :rolleyes:

StarDreamers.us · July 11, 2015

Thanks for the information. For the past ten years I have been using a NAPA dielectric grease in all my electric connections. Never have had a problem. I even use it in my flashlight radio battery connections.

Safe Travels!