dielectric grease ?!?!?!

[The Brockerts]

A search of TF of "dielectric grease" produced around 500 threads. I've not looked at all of them but a large %. A google search of "dielectric grease" produces this statement by the hundreds

"The grease does not conduct electricity, so it shouldn't be applied directly to the mating surfaces (pins and sockets) of an electrical connection"

and with that why do I see hundreds of TF post saying to use dielectric grease on mating surfaces, studs, shorepower connections?

What should be used on electrical connections like mating surfaces, studs, shorepower connections?

What gives?

How about PRO-SHIELD 7308 Electrically Conductive Grease?


The Brockerts

[TowLou]

Electric conductive grease could arc out to the other connectors or legs. I believe that grease would be used more with high amp switches. Dielectric grease helps with corrosion around the contacts.

[The Brockerts]

Yes, I can see electrical conductive grease could arc out to the other connectors or legs. On a single stud for example, it would stop moisture and then provide an electrical inhibitor between the contacts points, just the opposite of what you want. In this case wouldn't a conductive grease provide a better solution?

The Brockerts

[Nick F]

I was going to post my opinion, but realised that it would be just that (opinion). I Googled the question and found this article (which happens to be in line with my thinking and my professional experience) !

https://www.w8ji.com/dielectric_grea...ive_grease.htm

In short:
Dielectric (or non electrically conducting) grease does not stop electrical connectors from making good contact because it gets locally squeezed out and local metal-to-metal contact is not impeded. It does help keep air and corrosive contaminants away from the points of contact and, due to this, improves longterm connector reliability (you don't get corroded pins making poor contact). Greases like this are used in the electrical contracting industry (also known as de-oxidant grease).

Conductive grease is usually used to improve thermal conduction, rather than electric current conduction. It is used between transistors and their heat sinks.
Use of conductive grease on connectors is a very bad idea - it may cause current leakage between the pins, or to ground. If used on an AC connector it may cause ground faults and/or electric shocks.

Regards,
Nick

[The Brockerts]

Good find, I'm guessing the only way to really know is to setup a test bench and put some meters on the connections testing each product. Ohm's test might show something, any other ideas?

The Brockerts

[Barking Sands]

Originally Posted by The Brockerts

Good find, I'm guessing the only way to really know is to setup a test bench and put some meters on the connections testing each product. Ohm's test might show something, any other ideas?

The Brockerts

Ohms is good. In addition you can monitor temperature of the connection. If resistance is raised at the connection point because the dielectric is interfering the temperature is likely to rise at that now more resistant connection point. Really there should be a direct relation between ohms (at least the change in ohms from before dielectric and after) and heat through a connection. I have a Thermal camera I have been using to track down issues on the boat that has been indispensable.

I have some dielectric grease, power supply and stuff in the workshop. Maybe ill do a test. Maybe do it on both AC regular sockets and then DC as well. Would be interesting.

[Nick F]

Regarding the ohms test, the value of the resistance will probably be very small. It will be easier to detect a poor contact by passing a current (say 10 amps) through the connection and measuring voltage drop across the connection.

Note that to observe the "benefit" of using dielectric grease you would have to compare 2 connections, one with grease and one without and you would have to wait some years for the benefit of the grease to become apparent!

[backinblue]

The grease in non-conductive. It's counter-intuitive, but yes it should be applied to the contacts. It gets squeezed out and the connection is better and it helps insulate and prevent corrosion. There is a bench test on youtube I saw once where they did a continuity (ohm) test of a connection, then applied grease to the contacts and re-connected and the resistance when down.

[Barking Sands]

Originally Posted by Nick F

Regarding the ohms test, the value of the resistance will probably be very small. It will be easier to detect a poor contact by passing a current (say 10 amps) through the connection and measuring voltage drop across the connection.

Note that to observe the "benefit" of using dielectric grease you would have to compare 2 connections, one with grease and one without and you would have to wait some years for the benefit of the grease to become apparent!

The ohms test would have to be significant enough to observe. The same can be said of the voltage drop test. If you cant observe the difference in ohms then its very unlikely you will observe a difference in voltage, At least with the type of equipment and test conditions we are talking about. Most decent meters will go into the kilo and mega range for ohms. A megger may be handy. This unit could do it..lol https://www.mitchellinstrument.com/m...RoCS4AQAvD_BwE


But I dont know if a few Terra Ohms has any practical real life value through a spade connector or a shore power cord.

I also dont think there is any reason to do a long term test. The benefits of dielectric grease for guarding against or slowing down corrosion is well known. I think the important factor here is whether or not applying dielectric grease directly on contacts raises the resistance enough to cause issues. That test can be done in an immediate A and B fashion.

A quick look around find several tests showing good dielectric grease having little to no effect on resistance or voltage. Here is one,

https://www.youtube.com/watch?v=vACX...l=NewgateSimms

[Nick F]

A nice video, Barking Sands.

Note that the presenter uses the same method that I described to measure a very low resistance (passing a current through the connector and measuring volts drop). He (she?) got a value of around 2 thousandths of an ohm - typical multimeters might read down to a tenth of an ohm at best.

Bottom line - counterintuitively, the non-conductive grease does not increase contact resistance. Also, being non-conductive, it does not cause leakage between other circuits passing through the same connector.

Regards,
Nick

[backinblue]

Yes thanks BS. I think that is the video I was talking about or at least similar.

[The Brockerts]

So we have established that dielectric grease does not interfere with the electrical connection, good. It does provide environmental protection, good.

So why wouldn't we use something that does both of those things and improves the electrical connection? After all, isn't that what the connections is all about ?

On a mult-line connector, as in the video, dielectric grease is the only option, but on single spade connectors or other isolated connector's I'd like the environmental protection and the enhanced electrical properties of conductive grease.

The Brockerts

[RT Firefly]

Greetings,

Mr./Ms. TB. I came into some copper based conductive grease several years ago. I had considered applying it to spade type connectors, as you suggest. Initially I slathered it on my battery connections but found that it tended to migrate. Meaning it had the odious habit of hitchhiking on a shirt cuff, VOM leads, fingers and anything else that it came in contact with and depositing itself elsewhere, anywhere and everywhere.



I came to the conclusion that IF I ever was tracing circuits and had to disconnect and reconnect space clips or a few wires on a terminal block, for example, it could potentially create unwanted electrical paths due to it's nomadic and conductive nature. Not a problem with the dielectric stuff even if it got smeared about.



I think ample evidence has been presented that supports the use of dielectric greases rather than conductive types.

[Barking Sands]

TB...If you started with a proper and fresh connection in good shape I dont think you really could improve the connection much. If you could it would not be a good or proper connection to begin with. I think adding the grease will help preserve the good connection over time.

If you have a bad or poor connection there are several things you can do depending on what type of connection. If its a large connection that has enough access for mechanical cleaning thats one thing. But replacement is usually the remedy.

Electrical contact cleaners like Deoxit are IMO just for cleaning dirty connectors and the lightest of surface oxidation.

The only contact improver I have ever used with success was called Stabilant 22. It was used on Pratt & Whitney PW-305 engines on the FADEC cannon plugs to help correct nuisance engine codes. But in this case it is what the engineers came up with to provide a crutch for poor engineering, placement and materials. It is applied carefully and directly to mating surfaces in a particular manner.

[Barking Sands]

Originally Posted by Nick F

A nice video, Barking Sands.

Note that the presenter uses the same method that I described to measure a very low resistance (passing a current through the connector and measuring volts drop). He (she?) got a value of around 2 thousandths of an ohm - typical multimeters might read down to a tenth of an ohm at best.

Bottom line - counterintuitively, the non-conductive grease does not increase contact resistance. Also, being non-conductive, it does not cause leakage between other circuits passing through the same connector.

Regards,
Nick

I agree with you Nick. I dont think adding the dielectric grease is an issue either. And in that video he did the test on Molex style connectors..quite a low tension connection to move the grease out of the way and its still not an issue. In our industry we use Dow Corning DC 4 quite a bit and there has never been an issue.

The voltage drop test probably is a better test in most circumstances. I just never had an issue identifying poor connections using a good meter set to ohms. It doesnt go too many digits on the typical meter...but the overall range is quite large.

[Blissboat]

Originally Posted by RT Firefly

I think ample evidence has been presented that supports the use of dielectric greases rather than conductive types.

Agree, and really appreciate this thread's revelations about something that has piqued my own curiosity.

[EngNate]

I didn't read all the posts here, but did anyone mention kopr-shield? This compound is specifically made for mating surfaces of hi current connections and is widely used industrially. It fills minute gaps with conductive material and seals out moisture. It is also a good anti seize. This is the stuff for bolted connections and crimped lugs (treat the wire).

Silicone dielectric grease is excellent for all connectors, from antenna to shore power. It squeezes out to one molecule thickness and electrons pass through it by tunnel effect so it does not interfere with the connection. Other types of grease can interfere and should not be used. Treated metals will resist corrosion far longer, and just the thinnest coating does the job.

[Helmsman]

Look at Dow Corning High Vacuum grease. It is the dielectric used on the space shuttle and will insure a good seal against salt water. I use it after two electrical gurus that have taught me a lot in the past recommended it.



I would not use dielectric grease on N2K cables. Some do, but I have also heard a couple of techs state that it creates problems they get paid to solve.

[KnotYet]

Originally Posted by EngNate

I didn't read all the posts here, but did anyone mention kopr-shield? This compound is specifically made for mating surfaces of hi current connections and is widely used industrially. It fills minute gaps with conductive material and seals out moisture. It is also a good anti seize. This is the stuff for bolted connections and crimped lugs (treat the wire).

Silicone dielectric grease is excellent for all connectors, from antenna to shore power. It squeezes out to one molecule thickness and electrons pass through it by tunnel effect so it does not interfere with the connection. Other types of grease can interfere and should not be used. Treated metals will resist corrosion far longer, and just the thinnest coating does the job.

I have 2 bottles of Kopr-shield in my crimp terminal kit and use it in every one I do.

[Crusty Chief]

Dont know much about the physics of or the science of Dielectric grease. What I do know is the stuff works.
We used it on almost everything while I was in the Navy for 20 years. As a landscape contractor for almost another 20 years, all of the irrigation wire connectors we used were filled with the stuff. While cruising on our boat for 7 years I used it on all of my shore power cords, battery connectors and anywhere else I could think of. I didnt have any issues and no shore power cord damage. I swear by the stuff.
Clean the connector’s as best as possible and slather the stuff on. Yes it will “migrate”, but a small price to pay for safety in my mind.