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No !

Actually dielectric grease is often & usually of a silicone base. If you slather silicone inside an expensive adhesive lined heat shrink connector you will defeat the entire purpose of the adhesive lining as it will NOT adhere to silicone or grease and will make the added expense of the adhesive connector null and void. Remember NOTHING sticks to silicone not even new silicone. Adhesive lined heat shrink will NOT adhere to silicone dielectric grease!

Dielectric compounds are a nonconducting substance or an insulator by definition. I have often seen folks put dielectric compounds in the crimped connection itself.:hammer Wrong! This will and can severely reduce the electrical quality of the crimped connection and can actually lead to resistance. Remember dielectric grease is an insulator or conductivity eliminator and NOT a conductivity enhancer..

If you want to use a dielectric grease with NON adhesive lined heat shrink that is a better match but do so ONLY after you have made the crimp. Because of dielectric greases properties you may never get the heat shrink to stay in one place and it can move and slide around on top of the dielectric grease..

If using adhesive lined heat shrink connectors do not use a dielectric grease. Using a Dielectric grease with an adhesive line heat shrink tube is totally defeating the purpose of the adhesive.

Sometimes more is not always better....
 

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Telstar 28
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Basically, use dielectric grease on temporary or removable connections. Use adhesive-lined heat shrink tubing on permanent ones. Don't use both.

For example: Pre-amp RCA plug connection from your cd changer to your stereo amplifier, use dielectric grease. Crimping a ring terminal to the stereo's power line, use adhesive lined heat shrink tubing.
 

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Adhesive lined heat shrink will NOT adhere to silicone dielectric grease! ... I have often seen folks put dielectric compounds in the crimped connection itself.:hammer Wrong! This will and can severely reduce the electrical quality of the crimped connection and can actually lead to resistance.
Hmm ... let's discuss this a bit more. I am still trying to get my head wrapped around the conflicting strong opinions on this issue, after years of dealing with my boats' wires.

1. I agree that the grease can defeat the adhesive during shrinkwrapping, if the operator is not careful doing the procedure. But consider this: If the operator carefully puts a bit of grease only on the bare metal wires inside the crimp, then that portion of the adhesive-lined shrinkwrap away from the grease around the wire leading up to the crimp will stick fine to the wire, sealing out moisture from wicking up at that end. The adhesive might also stick over the crimp itself, but if some grease contaminates the surface of the crimp, then the grease could (in theory) do the job of keeping moisture out, while the grease around the wire ends inside the crimp protects those wire ends in a way the adhesive cannot, especially for terminals crimped on the end of a wire, as in at the ignition panel. If the joint is a crimp between two wires, and the operator keeps the grease off the wires leading up to the bare ends, then the adhesive will stick to the wires at both ends, keeping moisture out of the joint, but if any moisture does get in, then the grease is there as a second line of defence.

2. On another forum here, I asked about the best way to use dielectric grease. The reply I get to this question, consistently, is that a solid metal-metal connection (as in crimping or a tight bolt/thread fit) excludes the grease so that the grease does not increase resistance in the joint significantly.
 

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Well...

Hmm ... let's discuss this a bit more. I am still trying to get my head wrapped around the conflicting strong opinions on this issue, after years of dealing with my boats' wires.
What are the opinions you disagree with?

1. I agree that the grease can defeat the adhesive during shrinkwrapping, if the operator is not careful doing the procedure.
Careful or not with the proper crimp tool and a quality adhesive lined heat shrink connector there is no need for it..

But consider this: If the operator carefully puts a bit of grease only on the bare metal wires inside the crimp,
No, no, no!! Yes, I have strong opinions on this because a dielectric grease should never be put in between the wire and the terminal as it is intended to BLOCK conductivity NOT enhance it!!! Why not just strip the wire then wrap it with electrical tape then make the crimp over the tape??

A good many people, including folks on this forum, incorrectly use dielectric grease but it still does not make it correct usage..

then that portion of the adhesive-lined shrinkwrap away from the grease around the wire leading up to the crimp will stick fine to the wire, sealing out moisture from wicking up at that end. The adhesive might also stick over the crimp itself, but if some grease contaminates the surface of the crimp, then the grease could (in theory) do the job of keeping moisture out, while the grease around the wire ends inside the crimp protects those wire ends in a way the adhesive cannot, especially for terminals crimped on the end of a wire, as in at the ignition panel. If the joint is a crimp between two wires, and the operator keeps the grease off the wires leading up to the bare ends, then the adhesive will stick to the wires at both ends, keeping moisture out of the joint, but if any moisture does get in, then the grease is there as a second line of defence.
A proper adhesive lined heat shrink terminal covers the end of the wire! As I said use the right crimp tool and quality adhesive lined heat shrink terminals and there is no need for dielectric grease.


There is NO WAY water is wicking up through this crimped and cold formed terminal. The wire strands and the terminal have become one solid mass and like the wall of a copper pipe water is not getting through..


With a cheap crimper you may not get a true cold formed crimp. As you can see here the wire strands are still exposed and have not become one solid mass of copper.


Moisture wicking up the wire of a proper crimp stops dead at the crimp because it is truly cold formed meaning it has become one single mass of copper.

2. On another forum here, I asked about the best way to use dielectric grease. The reply I get to this question, consistently, is that a solid metal-metal connection (as in crimping or a tight bolt/thread fit) excludes the grease so that the grease does not increase resistance in the joint significantly.
This is good information. A proper crimped connection does NOT include a dielectric grease..

Please lets keep in mind that thousands of well drillers throughout this country use adhesive lined heat shrink & crimped Stakon connectors on wires submerged in artesian wells to depths of 300 feet or more with NO dielectric grease. These well pump wires stay dry while SUBMERGED with ONLY adhesive lined heat shrink...
 

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What are the opinions you disagree with?
I'm still forming an opinion about mixing dielectric and crimping, and getting opposite views from my betters. Your detailed reply and images are clarifying issues nicely for me.

On another forum here, I asked about the best way to use dielectric grease. The reply I get to this question, consistently, is that a solid metal-metal connection (as in crimping or a tight bolt/thread fit) excludes the grease so that the grease does not increase resistance in the joint significantly.
This is good information. A proper crimped connection does NOT include a dielectric grease..
I did not word myself clearly: I am being told that if I add dielectric grease to a joint of any kind, then during crimping or bolting the grease will be pushed out of the joint and onto the surrounding surfaces, leaving so little grease behind that any resistance it creates would be negligible. I presume your argument is that when proper crimp is done that squishes the wires into a solid mass in the crimp when dielectric grease is used, then it contaminates the joint sufficiently to increase resistance in that joint? I have no opinion on this, just trying to understand the best way to use dielectric grease. Thanks for working this through in such detail.
 

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Silicone (or dilectric) grease was developed back in the mid 60's for the specific purpose of promoting heat transfer from the the cases of power transistors which got hot to their heat sinks. Those cases were electrically "hot" as well and were insulated from the sinks by thin mica washers. Anyway, it was necessary that the transistor be insulated electrically and still be able to get rid of the heat it produced. Dilectric grease does that
Howard Keiper
Berkeley
 

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If you're going to use something other than heat shrink, I think ScottyT has hit on it. The purpose of putting something on the connection is to inhibit oxidation, especially the aggressive kind found in the marine environment.

I have a vintage automobile that is prone to corrosion on the fuses, which makes circuits stop working after a while. I put a thin bit of dielectric grease on the fuse connections. The grease scraped away from the metal-to-metal connection, so there was no reduction in conductivity but the grease did nothing to stop oxidation. A year later, the fuses were totally gray and starting to fail to conduct. This was in a NON-marine environment.

The penetrox sounds like a good idea if you're not going to seal up the connection with heatshrink.
 

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Penetrox is very good stuff. We used it on all aluminum wire connections. Aluminum got a bad name as a wire not because it was a poor choice, but because it was easy to apply it badly. One of the secrets was Penetrox. You had to wire brush the ends with a stainless brush coat them with penetrox and tighten the connection. Then, at the end of the day, tighten them all again. Those connections would never fail.

We always used Penetrox on all the battery connectors on our trucks and equipment. It always kept the corrosion from happening. However it DOES conduct electricity, so you have to be careful about getting it on the wire insulation, or you can get a shock from it!
 

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No-Alox (Ideal Corp) is good too.

Home Depot has it. Made for Al, but I have done salt chamber tests with it Cu as well.
 

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Maine Sail: What do you recommend for a "non-cheap" crimper for, say 16 to 10 gauge connections????:)
Now, having been a aircraft electrical inspector and think I can answer your question.
Rather than go for the generic plier type crimper, look for the ratcheting type as sold by west marine. This type of crimper will give you near weld conditions between the connector and the cable. You will need a separate wire stripper with this tool. I just purchased one from Harbor Freight for about $15, it works great.
One of the secrets of using crimp type connectors is to make sure you have not cut back the insulation to far. Particularly if you are using a shrink type connector as shown by Maine Sail.
On my 1987 Newport the wiring is copper coated with plastic. Most of the outer skin of the copper has corroded black. It's usable, but I have to make sure the outer skin of the strands is stripped back to remove all the corrosion which could cause a high resistance joint and a possible fire hazard.
 

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I'd point out that Sailorsolutions.com has a ratcheting crimper for heat shrink-type terminals that is far less expensive than the West Marine Ancor crimper.
 

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Practical Sailor says...

The July 2010 issue of Practical Sailor magazine contains the first results of their on-going "wire endurance test". In the article, they conclude that a product called "No-Ox-Id" does the best job of protecting connectors from oxidation. (My separate research clarifies that it is specifically No-Ox-Id's "A-Special" formulation that is intended for electrical uses.)

Practical Sailor makes it clear that nothing, especially not a dielectric grease, is to be put onto the strands of wires that are to be crimped, as it prevents the crimping action from cold-welding the strands into a solid piece of metal (and, as others have noted, introduces an insulator exactly where it's unwanted). Interestingly, they say that "a small amount" of No-Ox-Id can be added to the wire after crimping, and before applying heat-shrink, which (heat shrinking) they strongly recommend. (Perhaps obviously, one must ensure that at least some length of the heat-shrink tubing be adjacent to wire insulation that does not have No-Ox-Id on it...there's no reason to have the No-Ox-Id on the insulation at all.)

Practical Sailor also recommends applying No-Ox-Id onto push-on connectors, actually filling the female connector with the product so that it is exuded when the male connector is inserted. They further recommend applying the product to connectors that are attached with screws/bolts to terminals, but say that only a "light coating" should be used (the product will be exuded when the connection is tightened).
 
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