theory of grease for elctrical contacts/switches

Bill D · Oct 6, 2017

I want to grease the switch contacts of my buzz box welder because it gets damp in winter in my shed where it lives. I see dielectric grease and conductive grease recomended for switches and plugins..
I was taught that contacts should be clean and dry, not oily dirty.
I know on cars they use a lot of silicone grease to keep fixed plug in contacts dry. So is grease a good idea or not?
Bill D

dian · Oct 6, 2017

interesting. how can oil, or whatever, promote conductivity? what is a "contact cleaner" really. in the automotive world i come across watter displacing stuff. some kind of oil again. so if the contacts are oily, can they conduct more?

Scottl · Oct 6, 2017

I've seen a lot of switches that were greased. It was always dielectric grease and the switches used wiping contact.

MichaelP · Oct 6, 2017

Bill D said:
So is grease a good idea or not?

Lightly greased switch contacts (with a non-conductive grease) have about the same resistance as dry contacts, but greasing prevents oxidation.

Conrad Hoffman · Oct 6, 2017

Hint- ALL grease is "dielectric" grease unless it has something electrically conductive added to it. One should avoid silicone because it converts to abrasive silicon if any arcing occurs. So don't use the white silicone grease on contacts that switch live. It's fine for protecting connectors. The Superlube grease is recommended for electrical contacts, as are many Nye products.

TDegenhart · Oct 6, 2017

Go to your local electrical supplier and get a can of electrical grease. Yes, grease is used on electrical contacts, all the slide in and plug in breakers use it to protect against oxidation and galling.

Tom

Scottl · Oct 6, 2017

TDegenhart said:
Go to your local electrical supplier and get a can of electrical grease. Yes, grease is used on electrical contacts, all the slide in and plug in breakers use it to protect against oxidation and galling.

Tom

Back when I still had cars with distributors, official maintenance procedure was to grease the tip of the rotor with dielectric grease. This was especially important with aluminum contacts in the cap. Nowadays only the plug wires at the spark plugs and coil pack terminals need greasing.

Any auto parts store should have dielectric grease.

hermetic · Oct 6, 2017

Throughout my electrical engineering career, we used ordinary Vaseline on and sliding or closing contacts for arc suppression and anti oxidation. Works like a charm, and you can soon see what happens if it isn't used, especially in the old manual star/delta starters.

Bill D · Oct 6, 2017

These switches are only to be switched unloaded so arc suppression is not an issue. It is really just for my piece of mind that the contacts do not corrode from dampness in the air. I suppose the on/off switch carries a little load on startup and shutdown even if there is no welding going on.
Bill D

jim rozen · Oct 6, 2017

Do not use silicone-based dielectric grease on low voltage contacts like this.

You can remove it with either boiling NaOH or trichlor. Just saying.....

billzweig · Oct 6, 2017

Indeed, Vaseline works very well. I have been using it for decades. A thin coast is all that is needed.

hermetic said:
Throughout my electrical engineering career, we used ordinary Vaseline on and sliding or closing contacts for arc suppression and anti oxidation. Works like a charm, and you can soon see what happens if it isn't used, especially in the old manual star/delta starters.

JST · Oct 6, 2017

For contacts that are not often switched, there is a particular phenomenon which is a problem.

It is known as "fretting corrosion". What happens is that a little corrosion builds up on exposed surfaces. With temperature change, the parts move relative to each other, and one contact may "ride up" on the corrosion layer which is on the surface of the other contact. When the temp change is reversed, that contact may slide over on top of the corrosion which built up where it used to be. As this happens repeatedly over time, the corrosion may end up being thick enough to interrupt the contact between the parts, opening the circuit that the switch is supposed to have closed.

A small amount of grease cuts down on the corrosion rate, and tends to prevent the problem.

There are also issues of wear, when completely un-lubed surfaces rub over each other.

Dave D · Oct 6, 2017

On a sports car I owned, the previous owner had used grease on the battery terminals. I later found out that he had also greased the posts as well. It worked well enough at first but after a few months my amp guage would suddenly swing to the minus side, usually at an inopportune time such as rush hour. It took two attempts at cleaning the greasy clamps/posts to solve the issue (and I though I had done a good thorough job the first time). Since that time I've been leery about using Vaseline on or near any contacts unless it was specifically supplied with a new part like a distributor rotor.

So was this a fluke, that something like arcing between the clamp/post had degraded the grease or was this just a really bad idea in the first place?

Dave

mike 44 · Oct 6, 2017

Dave D said:
On a sports car I owned, the previous owner had used grease on the battery terminals. I later found out that he had also greased the posts as well. It worked well enough at first but after a few months my amp guage would suddenly swing to the minus side, usually at an inopportune time such as rush hour. It took two attempts at cleaning the greasy clamps/posts to solve the issue (and I though I had done a good thorough job the first time). Since that time I've been leery about using Vaseline on or near any contacts unless it was specifically supplied with a new part like a distributor rotor.

So was this a fluke, that something like arcing between the clamp/post had degraded the grease or was this just a really bad idea in the first place?

Dave

I don't think it was a fluke, Years ago I had problems with battery terminal corrosion. After cleaning the posts and connectors I used a silicone grease to stop corrosion. One day I could not start the car. I called my partner who had two sons that were auto mechanics. I related to oldest son what I did to stop corrosion. He told me to clean the posts and connectors again and do not grease them. Then he told me to dab paint on the posts ,that will delay or stop corrosion. After cleaning the terminal posts I started the car right up. Then dabbed a bit of white paint on the posts. Been doing that for 50 years now with success.
Ernie told me the silicone may have shorted the connection.
mike

JST · Oct 6, 2017

Certainly not "shorted", but could have caused a problem.

The battery connections, lead-to-lead, usually work quite well dry. And they are usually tight enough not to let any corrosion in. The problem with grease is getting too much on, and having temperature changes potentially let the grease lift the connectors out of contact.

I have seen a reasonable suggestion to make up the connection dry, but put a smear of vaseline, etc around the joint between the post and clamp. Keeps out corrosives, but is not in the actual connection.

whit3rd · Oct 6, 2017

Bill D said:
I want to grease the switch contacts of my buzz box welder... I see dielectric grease and conductive grease recomended for switches and plugins..

For best conduction in a heavy switch, you want a grease
that prevents metal/metal welding, and doesn't impede conduction. Caig Labs L260np grease is a good choice, it includes some tech wizardry that improves conduction.
I've tested with milliohm meters, it really does work.

Welding generates fumes (and dust) so it might pay to
wipe off the old grease and reapply from time to time.

DDoug · Oct 6, 2017

whit3rd said:
For best conduction in a heavy switch, you want a grease
that prevents metal/metal welding, and doesn't impede conduction. Caig Labs L260np grease is a good choice, it includes some tech wizardry that improves conduction.
I've tested with milliohm meters, it really does work.

Welding generates fumes (and dust) so it might pay to
wipe off the old grease and reapply from time to time.

While this may be the "ultimate"....the OP has a simple buzzbox,
being used in a low usage environment.

This grease you suggest, is it available in Home Depot ?
Corner store ?

billzweig · Oct 6, 2017

On battery terminals, and many other electrical cable connections, I am using Kopr-Shield Compound - a grease-like paste heavily loaded with fine copper particles. Not only prevents corrosion, but improves the contact.

Dave D said:
On a sports car I owned, the previous owner had used grease on the battery terminals. I later found out that he had also greased the posts as well. It worked well enough at first but after a few months my amp guage would suddenly swing to the minus side, usually at an inopportune time such as rush hour. It took two attempts at cleaning the greasy clamps/posts to solve the issue (and I though I had done a good thorough job the first time). Since that time I've been leery about using Vaseline on or near any contacts unless it was specifically supplied with a new part like a distributor rotor.

So was this a fluke, that something like arcing between the clamp/post had degraded the grease or was this just a really bad idea in the first place?

Dave

magneticanomaly · Oct 6, 2017

If there is a chance that the grease will migrate or be dragged across surfaces that must separate, and insulate contacts from each other, then a strictly non-conductive grease is needed, and its function is primarily to prevent corrosion and secondarily to lubricate the contacts to slow wear and ease operation.

Where there is little or no chance of migration, such a on the taps of an old Lincoln "tombstone" buzz-box welder, or on battery terminals, I'm with Billzweig and use something like "Never-Seez", grease with conductive metal and maybe graphite particles.

eKretz · Oct 7, 2017

Yeah silicone grease has already been mentioned twice as a no-no on live contacts, but I'll reiterate... Do NOT use it on live-switched contacts unless you want to replace them. The silicone grease will form silicon carbide abrasive crystals (right below diamond in hardness) if there is any arcing, and will erode the shit out of the contacts in short order. Use something made for live-switched contacts like Caig products or similar.

theory of grease for elctrical contacts/switches

Diamond

Titanium

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Titanium

Diamond

Diamond

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Hot Rolled

Diamond

Diamond

Stainless

Diamond

Hot Rolled

Hot Rolled

Diamond

Plastic

Diamond

Stainless

Titanium

Diamond; Mod Squad

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