Originally Posted By: brianl703
Dielectric grease prevents arcing. I used to (15 years ago) have an old IBM monochrome monitor. The flyback (which probably runs at about 10kV) started arcing. The arc actually burned a hole through the side of it. You could see it sparking and hear it crackling when the monitor was on. I applied some silicone caulk to it and that stopped the arcing. I probably could just as easily have used dielectric grease, but I didn't have any. The electrical insulating properties of dielectric grease are at least as good as silicone caulk.
Dielectric grease displaces air from the connection. Dielectric grease is actually a better insulator than air--and it also keeps water and dirt out of the connection. Air can ionize, once that happens, it conducts electricity. It becomes a very poor insulator! You could almost imagine that air is like a wall, and the voltage a battering ram. Once the voltage has gotten high enough to punch through that wall, there's a big gaping hole allowing all of the voltage in the circuit to leak through it.
Dielectric grease is a much stronger wall than air is. It does not ionize as easily as air.
I'm not sure that heatsink grease is the same as dielectric grease. Heatsink grease often has zinc oxide in it to make it conduct heat better.
I agree with all t hat and that was my understanding of dielectric grease. I was just commenting to the other poster about not using conductive grease.
I didn't mean that heat sink grease and dielectric grease are the same. Only that I think it could serve the purpose. My understanding was the grease conducts ehat better than air and the grese would fill the minute voids between the heat sink.