Dielectric grease - where NOT to use?

[Hakeem]

Dielectric grease seems like awfully useful stuff but I only ever hear of folks putting it on spark plug boots and trailer plugs. I do know not to put it on any metals about to be crimped, as well as keeping it away from painted surfaces as it is silicon-based. Otherwise - it’s pretty harmless stuff, right?

Context is, I wanted start a regular practice of applying a thin film of dielectric grease to plastic electrical plugs and connectors, along with the metal terminals contained within, anytime i had them apart. I figure this is in the spirit of good craftsmanship: helps prevent corrosion of the terminals AND facilitates removal of the connectors for the next person to work on it. But I don’t want to damage something inadvertently. So with all that said - anything I should NOT grease?

 

[bluedog225]

I put that **** everywhere. though I agree about the painting concerns.

I read some tests on lugs. No drop in resistance. Keeps the 02 away from the connection. Cheap insurance. No downside.

 

[zimman]

For me, any electrical surface exposed to air, corrosion, dirt.....ladda....ladda.......ladda.
I'd keep it away from body parts especially private areas. LMAO
Zim

 

[Tundra1]

I always assumed a bit of it makes sense on weatherproof electrical connectors as umbrella and raincoat concept. But recently on a few SMA videos I was watching he comments never to apply it to connectors that already have rubber seals. Thinking the rational there is that once applied they become dirt magnet if opened again. Also could potentially prevent proper mating of the pins. So I follow his guidance and no longer apply.

 

[theoldwizard1]

I do know not to put it on any metals about to be crimped,

Why ? Better after crimping.

I wanted start a regular practice of applying a thin film of dielectric grease to plastic electrical plugs and connectors, along with the metal terminals contained within, anytime I had them apart.

Probably not a good idea on small female connectors, like "weather pack" connectors. A little TOO MUCH will cause the male pin to deform the female socket, possible causing an open or intermittent.

Larger pin and socket (like Molex) is probably okay. In the early days of electronic engine controls, we used it on everything ! One of the best uses was INSIDE the distributor cap on all of the "contact". (I say "contact" because other than the center tower to the rotor there was no mechanical contacts ! The dielectric grease significantly cut down RF noise.)

 

[Jasmith801]

Is dielectric grease actually a insulator and not good at conduction?

 

[Old Man Roger]

Is dielectric grease actually an insulator and not good at conduction?

It is a non conductor, but it’s so thin that any metal to metal contact will scrape it away, while still protecting everything around it.

 

[jkeyser14]

I always assumed a bit of it makes sense on weatherproof electrical connectors as umbrella and raincoat concept. But recently on a few SMA videos I was watching he comments never to apply it to connectors that already have rubber seals. Thinking the rational there is that once applied they become dirt magnet if opened again. Also could potentially prevent proper mating of the pins. So I follow his guidance and no longer apply.

It can also react negatively with certain o-ring materials.

 

[jkeyser14]

Is dielectric grease actually a insulator and not good at conduction?

Depends on the specific grease. Most is non-conductive, but there are brands with conductive metal particles.

 

[Farmall450]

It can also react negatively with certain o-ring materials.

Yes - this. Deutsch and others may react poorly. But they're already weathertightish, so. I imagine the cavity plugs may also swell.

 

[BlakeTheCarGuy]

I use it on spark plug boots, battery terminals and most electrical connectors.

 

[dscheidt]

Is dielectric grease actually a insulator and not good at conduction?

Yes, which is why it's traditionally been used on spark plugs (and called 'tuneup grease' by old timers). It keeps spark from jumping from the plug to something you don't want it to. It's mechanically displaced when the connection is put together, leaving metal to metal contact, surrounded by insulating grease.


Nearly all grease is non-conductive and would work for that (lots of people use vaseline on battery terminals), but dielectric grease has an important advantage: it's silicone based. Because it's a silicone grease, and not a petroleum grease, when there *is* arcing and the grease decomposes (burns), it doesn't leave a carbon track. carbon tracks are conductive, and provide a lower resistance path. once there's a track, there can be more arcing, which makes for more carbon, ...

 

[Old Man Roger]

It can also react negatively with certain o-ring materials.

I’ve never noticed. I have seen oil soften them, but not dielectric grease. It’s usually silicone based and doesn’t hurt most rubber. Ironically, it’s not great for silicone rubber.

 

[WisJim]

Depends on the specific grease. Most is non-conductive, but there are brands with conductive metal particles.

"Dielectric" by definition is non-conductive.

 

[Wiz02]

Other uses are for weatherstripping. GM recommended using it on the weatherstrip to eliminate rear hatch squeaks and door seals.

I don't know if the recommendation is current. This was advice from over 10 years ago.

 

[rlitman]

Is dielectric grease actually a insulator and not good at conduction?

Yes, it's an insulator, BUT, metal oxides are semi-conductors and can insulate more in the right situations. Calling out grease as an insulator ignores what's happening on the microscopic scale around the metal to metal contact. Earth is an insulator too, yet we place ground rods in it.

Depends on the specific grease. Most is non-conductive, but there are brands with conductive metal particles.

Dielectric grease is by definition non-conductive!

...Nearly all grease is non-conductive and would work for that (lots of people use vaseline on battery terminals), but dielectric grease has an important advantage: it's silicone based...

Well, when you buy a packet or container of it at the auto-parts counter, it probably is. The CRC dielectric grease I often use is all silicone, and is safe for use that silicone grease is good for (for example around rubber seals that get hurt by petroleum products). But I wouldn't say that all dielectric greases are silicone based.

 

[kbuhagiar]

Okay, so...

It's OK to coat my 12V car battery terminals in dielectric grease to prevent corrosion (even though dielectric grease, by definition, is non-conductive) because assembling the components will scrape away the grease and restore metal-to-metal contact.

Have I got that about right?

 

[bluedog225]

Okay, so...

It's OK to coat my 12V car battery terminals in dielectric grease to prevent corrosion (even though dielectric grease, by definition, is non-conductive) because assembling the components will scrape away the grease and restore metal-to-metal contact.

Have I got that about right?

The studies I’ve seen show no reduction in resistance. It gets out of the way for metal to metal contact. And reduces corrosion of those same contact areas by excluding oxygen.

Super lube is allegedly food safe so no worry with skin contact. Cheap and easy.

 

[theoldwizard1]

... but dielectric grease has an important advantage: it's silicone based. Because it's a silicone grease, and not a petroleum grease, when there *is* arcing and the grease decomposes (burns), it doesn't leave a carbon track.

This is the KEY FEATURE of dielectric grease !

 

[Codyboy]

"Dielectric" by definition is non-conductive.

This.
Dielectric grease is an insulator.

Do not apply it to something you want to conduct electricity.

I don't know how many times I've had to stop or say no don't do that .

100s , 1000s idk. Guys want to put 3m Dielectric grease on current carrying parts. This is 35kv stuff. .
No matter what you tell yourself, eventually the connection will fail. Ive seen it a lot.
Guys would put it on a threaded probe on a 12kv or 35kv elbow. Yeah it may not fail right away but it will fail.
Keep it off of contact points.

However we use it all the time on stuff that is not supposed to carry current.

I think a lot of people think its contact grease. Which is the exact opposite of Dielectric grease.

 

[dave*99]

This.
Dielectric grease is an insulator.

Do not apply it to something you want to conduct electricity.

I don't know how many times I've had to stop or say no don't do that .

100s , 1000s idk. Guys want to put 3m Dielectric grease on current carrying parts. This is 35kv stuff. .
No matter what you tell yourself, eventually the connection will fail. Ive seen it a lot.
Guys would put it on a threaded probe on a 12kv or 35kv elbow. Yeah it may not fail right away but it will fail.
Keep it off of contact points.

However we use it all the time on stuff that is not supposed to carry current.

I think a lot of people think its contact grease. Which is the exact opposite of Dielectric grease.

High voltage stuff (35kV etc) is subject to corona and various other high voltage phenomenon.

12V battery terminals, trailer connectors etc. benefit from dielectric grease to prevent corrosion. Low voltage landscape lighting wire nuts are often supplied prefilled with dielectric grease. The grease is displaced under clamping pressure.