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Old 05-03-2021, 04:54 PM   #1
Rob Doe
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Default Does anyone use carbon conductive grease to protect ground points?

Researching how to restore a distributor, I noticed there were two or more places where it was suggested that one should remove the paint from the touch points of a ground connection. Namely the condenser ground on the side of the distributor casting and the base of the distributor casting where the pin and the lower surface touches the cylinder head.

Does anyone use a carbon conductive grease to prevent corrosion at these ground points???
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Old 05-03-2021, 05:06 PM   #2
Synchro909
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Default Re: Does anyone use carbon conductive grease to protect ground points?

I've never heard the term "Carbon conductive grease" so I can only guess what you are talking about. However, I always use a tiny amount of dielectric grease on any electrical contact
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Old 05-03-2021, 05:18 PM   #3
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Default Re: Does anyone use carbon conductive grease to protect ground points?

Electrical connections are best when they are simply clean and tight. Dielectric silicon grease such as Dow Corning number 4 is used in the aerospace business to keep connections from corrosion. Most of the stuff is compressed out of the way when tightening a terminal but there is still enough in place to prevent corrosive action from taking place in the joint. All it takes is moist air to start the corrosion process. In swampy areas like under the hood or close to the frame under a car, a terminal can be exposed to all sorts of corrosion causing contaminants. Auto storage batteries generally have their own built in oxidizers to start that process.
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Old 05-03-2021, 05:22 PM   #4
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Default Re: Does anyone use carbon conductive grease to protect ground points?

Quote:
Originally Posted by Synchro909 View Post
I've never heard the term "Carbon conductive grease" so I can only guess what you are talking about. However, I always use a tiny amount of dielectric grease on any electrical contact.
X2 on the dielectric grease, even on light bulb contacts.
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Old 05-03-2021, 07:29 PM   #5
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Default Re: Does anyone use carbon conductive grease to protect ground points?

"What is dielectric grease?"

Quote:
The grease does not conduct electricity, so it shouldn’t be applied directly to the mating surfaces (pins and sockets) of an electrical connection... Dielectric grease can also be applied to the metal parts of virtually any electrical connection that will be exposed to the elements to serve as a sealant that protects the connection from contamination and corrosion. This should be done very carefully, as the grease will cut off the flow of electricity through the connection if some of it is left between the mating surfaces.
I mention this only because it's easy for readers to misinterpret the "electric" in dielectric grease. A good way to think about dielectric grease is as a gasket for electric contacts. You don't put it on the contact, you put it around the contact to seal it off from the environment. A lot of folks argue that the grease will be pressed out of the way when you make the connection, which... I guess that usually works? But it's important to be clear that the grease itself has no conductivity.

There are anti-corrosion compounds that are conductive, such as carbon conductive paste, which is what the OP was asking about.

Last edited by alexiskai; 05-03-2021 at 07:38 PM.
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Old 05-03-2021, 08:33 PM   #6
Bob from Northport
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Default Re: Does anyone use carbon conductive grease to protect ground points?

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Old 05-03-2021, 08:35 PM   #7
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Default Re: Does anyone use carbon conductive grease to protect ground points?

In many electronic applications, berylium copper internal star washers are used to insure a
good ground between parts. When squeezed to spec, there is actual metal
migration. (mechanical fusion like brazing)
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Old 05-04-2021, 03:42 AM   #8
Patrick L.
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Default Re: Does anyone use carbon conductive grease to protect ground points?

Before this new-fangled dielectric stuff I/we used petroleum jelly wherever it was thought corrosion could happen.
Since our distributors are prone to 'sticking' themselves in the hole I give the hole and distributor a bit of grease or never seize. The lock screw provides enough of a ground.
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Old 05-04-2021, 06:28 AM   #9
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Default Re: Does anyone use carbon conductive grease to protect ground points?

I always try to use dielectric grease on all electrical connections, including bulbs.
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Old 05-04-2021, 08:42 AM   #10
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Default Re: Does anyone use carbon conductive grease to protect ground points?

The star washers are specified for ground connections in solar panels which are subject to environmental oxidation.

I use dielectric grease on all electrical connections and buy the copper containing grease from McMaster Carr.

No two surfaces are in 100% contact. There are always microscopic high spots. The grease does not get squeezed out of the contact and a film is always present. It helps that there is some grease surrounding the contact. Battery connections ara an example where grease is smeared on the outsides of the contacts.
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Old 05-04-2021, 09:51 AM   #11
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Default Re: Does anyone use carbon conductive grease to protect ground points?

The tern plated copper of most electrical terminals is soft enough to act as a gasket but moisture still has a way of getting in to some degree due to capillary action and oxidation over time. It just takes it longer. Dielectric grease is used mostly to prevent bridges to other electrical terminals than can happen with some conductive materials like carbon. Folks have used petroleum jelly, axle grease and even oil to seal terminal joints but the silicon grease is the least likely to melt off or become contaminated to the point that is can conduct electrical flow to some degree.
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Old 05-05-2021, 11:08 AM   #12
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Default Re: Does anyone use carbon conductive grease to protect ground points?

We used to use Penetrox for dissimilar electrical connections;

https://www.gescan.com/products/10-a...inum-to-copper
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Old 05-06-2021, 07:51 AM   #13
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Default Re: Does anyone use carbon conductive grease to protect ground points?

Sanchem No-Ox-Id-A has been around over 100 years. It's nonconductive and won't run or wash off. Ma Bell used to buy it by the boatload.

Coat contact surfaces before joining, it fills in the rough spots and prevents corrosion.

Also a good antiseize.
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Old 05-06-2021, 09:30 AM   #14
rotorwrench
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Default Re: Does anyone use carbon conductive grease to protect ground points?

The Penetrox is likely a zinc oxide material mixed in with a form of grease or oil. The old Sanchem product is basically a form of cosmoline compound.

No corrosion preventative compound is perfect and all of them eventually break down in the natural elements over time and that includes silicon grease and cosmoline. Any material that is conductive, would have to be carefully applied to terminals to insure it doesn't drool over to a grounded surface or another electrical terminal of a different circuit. The cross conductivity can cause problems.

On the Bell 206 Jet Ranger type aircraft, there is a requirement to coat the main rotor control pitch link swivels with Black Bear par-al-ketone which is a cosmoline product. Every 2-years, the coating has to be removed and the surfaces inspected for any signs of corrosion. If the parts are good to go than they are recoated with the Black Bear. The cosmoline can harden and crack over time so this procedure further prevents the posibility of corrosion on these critical parts. Cosmoline is good stuff for corrosion protection but it's not perfect. I remember asking folks that were selling old war surplus items that had been stored for many years using packaging that included cosmoline about whether they had ever found corrosion and most of them have. Many of the crates or boxes would have stuff that looked brand new and others had either not been coated properly or the coating broke down with moisture contamination and the whole container of parts were mostly beyond use with corrosion.
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