Dielectric greas on electrical connections

[pablosgirl]

Just had my st60+ mast head wind instrument repaired by Raymarine factory.  The wiring in the unit was corroded due to water collecting in the socket at the top of the mast where the arm of the instrument joins the cable.  Raymarine recommended cleaning the socket with alcohol and putting plumbers silicon on the threads of the compression nut that holds the wind instrument arm to the cable mount to keep water out of the connection.  I was thinking that applying dielectric grease to the pins of the arm where they fit into the cable socket at the top of the mast would prevent water from reaching the connection pins and prevent corrosion and shorting out the unit. 

Has anyone had a similar experience?

Mainsail is this a good idea? or is there a better method to protect the connection?

I installed this unit in 2009 after the original unit was damaged in hurricane Ike.  A little over a year ago it started working intermittently and eventually stopped working all together.  I took the unit down last month and sent it into Raymarine for repair.

[mainesail]

Dielectric grease can work ok here but just don't ever try to label anything after you've applied it and silcone greases can damage o-rings and some plastics..  Nothing will ever stick once you've used a dielectric grease.

Any dielectric grease is technically non-conductive so a balance between limiting corrosion and over application needs to be made. These wires pass little to no current so high resistance is pretty much a non-issue. 

I use a product called DeoxIT D5 for cleaning terminals then followed up by DeoxIT Shield for protection. My wind vane terminals look as good as new...

[Ron Hill]

Guys : After I made a connection and wanted to make it water resistant I sprayed it with "BoeShield" (T9? or T7?)  Never had a problem with moisture intrusion after that.  It leaves a waxy coating over the connection.

A thought

[Stu Jackson]

Perhaps it might be helpful if folks mentioned whether they "slathered" this "stuff" on before or after they made the connection.

Putting dielcetric grease between the ring terminal and the bus bar may not be such a good idea, since the grease is an ISOLATOR.

"Slathering" it on, AFTER the connection is screwed down, clean surface to clean surface, would work to keep it secure.

Maine Sails': "DeoxIT D5 for cleaning terminals then followed up by DeoxIT Shield" should be used in the correct order.

[KWKloeber]

I have used SuperLube PTFE gel and it seems to work well.

I've read (on the net = true) that applying DG before making the connection (screw terminal, crimp, etc.) does not increase the resistance.  Basically the arguments were that, the metal-to-metal pressure of the connection leaves no DG between parts.  Of course what remains (outside the direct m2m contact points) prevents corrosion creep. 

I haven't tested the "resistance theory," but it would make an interesting exercise and will test it out the next time I make some connections.  I think it makes sense -- DG isn't very "stout" and any metal to metal scraping would probably scrape/squeeze it off the surfaces.  Now if if axle grease was slathered on a terminal screw I could see it being a concern.

Witness the recommendations for DG on spark plug boots.
https://tds.us.henkel.com//NA/UT/HNAUTTDS.nsf/web/E7D49FEC1C1903B6882571870000D946/$File/DIEG-EN.pdf

Certainly there's not much pressure on a SP from the boot contact.

I have seen published test data that debunks the theory that DG is a thermal isolator if used under a component that's pop riveted or bolted to a heat sink.  The data showed no increase in temp of the component w/ or w/o DG being applied.

Again, this is only info I've seen, and can't attest to it's veracity.  Others' mileage may vary.


KK

[dfloeter]

On this topic, some years ago, when venturing into salt water I sprayed Boeshield T-9 on wire connections, even the back of the fuse panel.   The one place where I overdid the spraying was the remote VHF mic plug.   No measure of cleaning with multiple solvents ever uninsulated that connection and
I had to run an extension wire out the companionway.   Replacing the plug at that point was lower on the priority list with the ports leaking in torrential Florida rains and other issues.  Would a dielectric grease have worked on this low power draw plug or could I have just left it alone?   Was the T-9 a good product to begin with?

[mainesail]

I have used SuperLube PTFE gel and it seems to work well.

I've read (on the net = true) that applying DG before making the connection (screw terminal, crimp, etc.) does not increase the resistance.  Basically the arguments were that, the metal-to-metal pressure of the connection leaves no DG between parts.  Of course what remains (outside the direct m2m contact points) prevents corrosion creep. 

I haven't tested the "resistance theory," but it would make an interesting exercise and will test it out the next time I make some connections.  I think it makes sense -- DG isn't very "stout" and any metal to metal scraping would probably scrape/squeeze it off the surfaces.  Now if if axle grease was slathered on a terminal screw I could see it being a concern.

Witness the recommendations for DG on spark plug boots.
https://tds.us.henkel.com//NA/UT/HNAUTTDS.nsf/web/E7D49FEC1C1903B6882571870000D946/$File/DIEG-EN.pdf

Certainly there's not much pressure on a SP from the boot contact.

I have seen published test data that debunks the theory that DG is a thermal isolator if used under a component that's pop riveted or bolted to a heat sink.  The data showed no increase in temp of the component w/ or w/o DG being applied.

Again, this is only info I've seen, and can't attest to it's veracity.  Others' mileage may vary.


KK

I think under many circumstance adding a DG can be more beneficial than detrimental in that it helps keeps out corrosion which is arguably a lot more detrimental... However there are situations and manufacturers who emphatically state not to use it in certain situations...

Evinrude E-tec 75 HP Service Manual Pages 149 & 150:

"CONNECTOR SERVICING DEUTSCH CONNECTORS

IMPORTANT:
Electrical: Electrical grease is recommended. Incorrect grease application can cause
electrical or warning system problems.

To disconnect the connector, press the latch and pull the connectors apart.

To connect the connector, confirm that the seal is in place. Clean off any old grease and dirt from
connectors. Apply a light coat of Electrical Grease to the seal. Push connectors together until latched.

AMP AMP CONNECTORS Pg 150:

IMPORTANT: Always use the appropriate meter test probes and adapters when testing components fitted with these terminals. Electrical grease is NOT used on AMP connectors."