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Author Topic:   Dielectric Compound -- Misunderstandings
number9 posted 07-15-2009 04:27 AM ET (US)   Profile for number9   Send Email to number9  
Must admit I have been confused for years on the issue of the proper uses of Dow Corning® DC4 Electrical Insulating Compound. My first experience was seeing it used on/in electrical connectors for a nose landing gear indication system.

Haven't used the stuff for years due to my misunderstanding of how and why it works. Those of us with a good understanding of electronics understand dielectric to mean non-conductive. My thinking was don't do anything to prevent conduction.

A topic posted yesterday prompted me to do a Goggle search. Among the links that came up was our site. Also a YouTube caught my eye also, where they suggest it on connectors.

Thanks to one of the three who offered their opinion on the video, "Dielectric grease is NOT conductive. If it conducted it would short out the terminals". That's why it's ok to use on lamps and in multi-conductor connectors. As others have said, "its really soft and gets out of the way" of making a good connection.

My conclusion is it does not inhibit conduction on connectors, promotes long term conduction by helping to prevent corrosion and prevents short circuits due to water.

New 2 Whalers posted 07-15-2009 09:27 AM ET (US)     Profile for New 2 Whalers  Send Email to New 2 Whalers     
This was cut and pasted from a manufacturer's site and explains its use.

<Silicone Dielectric Compound is formulated to lubricate and protect certain electrical connections. Heat and high voltage create problems when it's time to replace spark plugs and wires. Boots tend to soften, light bulbs dry out and stick, sometimes breaking off. Silicone Dielectric Compound helps prevent this from happening.>

jimh posted 07-15-2009 01:51 PM ET (US)     Profile for jimh  Send Email to jimh     
Dielectric grease is non-conductive. If you apply it to electrical conductors it creates a non-conductive layer on top of them. In low voltage circuits it does not take much insulation to stop the flow of current.

The intention of dielectric grease is to be applied to the connector, not to the conductors or conductive contacts. I keep saying this, but apparently people choose to believe that applying a non-conductive grease to a conductor will make it work better. I use dielectric grease as a lubricant and sealant, exactly as mentioned by the manufacturer in the cited passage above. I do not apply it directly to the conductors, and in fact I go out of my way to keep the grease away from the conductors.

If I want to enhance the electrical connection between conductors, I use a conductive grease like BURNDY PENETROX.

jimh posted 07-15-2009 01:54 PM ET (US)     Profile for jimh  Send Email to jimh     
I watched enough of the cited video to hear the narrator say, "Dielectric grease is a grease that conducts electricity..."

At that point I stopped listening. Sorry, but dielectric grease does not conduct electricity. There really is not an "issue" about this. There does seem to be a lot of confusion.

number9 posted 07-16-2009 02:26 AM ET (US)     Profile for number9  Send Email to number9     
I also heard that and was rather turned off by it. If you noticed it was a Lubrimatic product called Electrical Contact Grease. They don't have a good description or data sheet on their website and don't claim it to be dielectric. I used the link because of the comments below it.

I think you are reading far too much into the "dielectric" of the product names as you discourage continuousWave readers from using known good products that can help us all.

If you read my post even I admitted misunderstanding the uses and reading too much into "dielectric" myself for thirty years. You and I have both missed out using a great product because of backgrounds that equate dielectric with non-conductive in the wrong application/text. Can't see the forest because of the trees. In previous same basic subject topics you have said the same old thing, don't want to listen to others or open your eyes to what the rest of the world is doing.

Below is well known in the MRO industry and a reputable company. Their description and recommendations to use on connectors and terminal prior to assembly.
From Loctite, E7D49FEC1C1903B6882571870000D946/$File/DIEG-EN.pdf
For connectors and battery terminals
1. Make sure ignition system is off.
2. Clean surfaces with appropriate cleaner such as Loctite® Pro Strength Parts Cleaner or Loctite®
Battery Cleaner.
3. Coat both parts with grease.
4. Reassemble.

A couple more comments from other forums:
It is non-conductive, but when you slide the connectors together there is metal-to-metal contact and the grease gets displaced but the area around connector is protected from moisture. If the grease was conductive it would be too easy to get "bleed" from one pin to another in a connector if the grease got hot and liquified and spread.(Duh, that's
why Dow called it dielectric and why you don't want to use conductive grease in that application)
Using a bit more grease is usually a wise idea, since it protects the connectors from corrosion by displacing water and reducing exposure to oxygen. If the contact between the two pieces is such that enough grease is between them to cause a problem—you've got other problems with the connection (that's when conductive grease saves the day). The connection should be tight enough that it forces the grease out of the way.

On the Ogeechee

swist posted 07-16-2009 05:17 PM ET (US)     Profile for swist  Send Email to swist     
So what then is the difference between dielectric grease and grease grease? I do not believe the latter conducts electricity either. As a matter of fact at the yard where they do my off-season Whaler work, the mechanic, who is very competent on everything I've needed so far, says he uses plain old grease on trailer connectors. Same theory as stated above, the forced metal-to-metal contact pushes it out of the wat of the flow of electricity, however it fills in all the adjacent nooks and crannies and prevents corrosion.

The term "dielectric" might imply that it in fact is a better insulator than regular grease. That's the only thing I can imagine distinguishes it.

number9 posted 07-16-2009 07:21 PM ET (US)     Profile for number9  Send Email to number9     

Dielectric compound is moisture resistant and doesn't mix with water. Regular grease may over time absorb moisture causing voltage leakage and/or corrosion, lower melting point, picks up more dirt and messier. Trailer plugs don't normally stay connected for a long period of time. You wouldn't want to use on a hard to get at connector subjected to moisture for a long period of time. What your competent mechanic is doing is fine for the application and as you point out it pushes out of the way to make good contact.

It's really a specialty grease without a huge market due to expense. If you wanted to market the stuff just for electrical use a better name might be "Terminal and Contact Grease" to avoid the confusion and save the dielectric description for use in it's data sheet. You might consider dielectric grease a misnomer.

deepwater posted 07-16-2009 08:46 PM ET (US)     Profile for deepwater  Send Email to deepwater     
1989 Johnson 88SPL/Boston Whaler Montauk ,, I removed any and all steel nuts in electrical wiring system on the motor and the Moutauk the first year (i hate rust),, The use of dielectric grease was wide spread and liberal on any and all plugs/paddles/blades/boots/terminals that i could reach as was the use of spray silicone(food grade)on hoses and wires ,,To date the 88SPL has never let me down or failed to bring me in ,,Once after sitting for 4 years it would not start or run well (carbs?)but it turned over like new and fired,,After the carbs were cleaned it still ran like new ,,Its been sitting all winter now and i need to fire it up soon but i know it will start and run well,,There is NO corrosion on my terminals or connections anywhere ,,and anyone is welcome to come up and look for them selves ,,Phil T ? (casco bay outrage)your close
number9 posted 07-18-2009 04:33 AM ET (US)     Profile for number9  Send Email to number9     
Here's another link found on the CRC site also suggesting use on contacts, lamps and connectors. aspx?Name=Electronics%20Grease&Type=Literature&Format=PDF& Filename=ElectronicsGrease.pdf&URL= ElectronicsGrease.pdf

deepwater your experience though is the proof in the pudding.

jimh posted 08-07-2009 11:14 PM ET (US)     Profile for jimh  Send Email to jimh     
In circuits where the voltage is 12-volts, you don't need much insulating capability in the grease. The dielectric grease used on spark plug boots is intended to have very good insulating properties so that the high voltage spark cannot leak to ground via the grease. But in 12-volt circuits, a few molecules of anything non-conductive will stop current flow.

The reason dielectric grease is applied to spark plug boots is so you can get them off six years later when it is time to change the plugs. Without a little grease the rubber boot would be quite stuck to the plug body.

Apparently, in spite of repeating myself frequently on this topic, people seem to believe that I am against all use of dielectric grease. That is not correct. I use dielectric grease on certain connectors, but I do not slather it on the electrical contacts themselves. I use it to help mate and seal the plug and socket body of the connector. If you read the manufacturer's recommendations, this is precisely what is called for.

I don't know who started this notion that you apply an insulating grease to electrical conductors before you try to get them to conduct to each other. It's a strange use of a material intended for something else.

I am also not much of a fan of routine use of "contact cleaners." The best contact is a dry and clean contact. When you get into the habit of spraying chemical cleaners onto contacts on a routine basis, you will find that the procedure becomes a self-fulfilling prophesy. The connectors get so much gunk on them from each spray that it takes a new spray to remove the dried gunk left behind from the last spray.

If there is a connector in a marine environment that needs to be sprayed with "contact cleaner" and then packed with dielectric grease before it is connected to its mate, that connector does not belong in a marine environment and should be replaced with something more appropriate.

fishgutz posted 08-14-2009 03:25 PM ET (US)     Profile for fishgutz  Send Email to fishgutz     
So, what should we be using for electrical connections on our boats?

I was at a national electrical supply store and the guy working the counter looked at me like I was crazy when I asked for something that would protect from corrosion AND be conductive. Everything they had did basically the same thing as dielectric grease.

fishgutz posted 08-14-2009 03:43 PM ET (US)     Profile for fishgutz  Send Email to fishgutz     
In regards to what we should be using. It would not work too well for me to use a spray. The confined areas and exposure to other surfaces in my small Dauntless 14 could make a spray very messy.
HAPPYJIM posted 08-14-2009 09:00 PM ET (US)     Profile for HAPPYJIM  Send Email to HAPPYJIM     
Does this thread have the same intentions of use as this one?

jimh posted 08-14-2009 09:09 PM ET (US)     Profile for jimh  Send Email to jimh     
"...what should we be using for electrical connections on our boats?'

I recommend you use electrical connections on your boat which are designed for marine applications. That is, connections which tend to be sealed against intrusion of water.

fishgutz posted 08-14-2009 09:54 PM ET (US)     Profile for fishgutz  Send Email to fishgutz     
All righty then.

What kind of connections are those? Are they different from the ones that came on the boat?

jimh posted 08-14-2009 10:17 PM ET (US)     Profile for jimh  Send Email to jimh     
This thread is discussing the use or misuse of dielectric greases. To change the the topic to electrical connectors for marine use, please start a new discussion.
fishgutz posted 08-14-2009 10:49 PM ET (US)     Profile for fishgutz  Send Email to fishgutz     
You're the one who changed the subject.
jimh posted 08-14-2009 11:49 PM ET (US)     Profile for jimh  Send Email to jimh     
Now you've changed the topic of discussion to the discussion itself. This generally spells doom for anything that comes afterwords.
HAPPYJIM posted 08-15-2009 08:15 AM ET (US)     Profile for HAPPYJIM  Send Email to HAPPYJIM     
After reading the application sheet, It looks like it can be used on any electrical connector, ignition systems, spark plug connections, battery connections, electrical systems and when assembling certan metal to plastic and metal to rubber assemblies. I would use it on anything that didn't require constant plugging and unplugging.
fishgutz posted 08-15-2009 09:14 AM ET (US)     Profile for fishgutz  Send Email to fishgutz     
Jim, you're cracking me up. Oops, now I changed the topic again.

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