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Electrical Connection Maintenance

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Lee Panza
Captain

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USA
465 Posts

Initially Posted - 03/30/2014 : 07:38:51

This is actually a response to something posted to a different thread, but by the time I finished writing it I thought it should probably be submitted under a new topic rather than hijacking that thread.

Bruce Ross on Voyager posted: "I replaced the Anchor light with a 2nm LED. I sanded the fixture contacts and bent them to make good physical and electrical connection."

That jumped out at me, and I wanted to express a word of caution about something.

Sanding electrical contacts does temporarily improve their conductivity, but it can be a short-lived improvement. The grit gouges lots of fine scratches in the oxidized surfaces, leaving some ridges of bare metal to contact ridges of bare metal on the mating surface, but that same condition promotes re-oxidation by exposing so much more non-contacting surface area between the ridges. The actual contact area is reduced to just the microscopic ridge intersections. When you sand-off electrical contacts (rather than cleaning them chemically or by polishing) it's a good idea to introduce something to prevent re-oxidation. Even dielectric grease would help (dielectric grease is, by definition, non-conductive but it's so soft that it gets squeezed out of the actual metal-to-metal contacting points and it usually doesn't interfere with the conductivity). A better material to use, however, is conductive grease.

Do an Internet search for conductive grease, or for MG Chemicals 846 ($13.95 at Amazon).

Use it very sparingly, because if excess conductive grease runs into the wrong place when it gets heated by the lamp it can provide a short-circuit path. With that caveat, a very small dab of conductive grease is a good idea where contacts have been sanded clean. I sometimes put a really small dab of conductive grease in the middle of the contact area (or on the individual pins in a multiple-conductor pin-&-socket connector) and then I swab around it on the contact surfaces (or I slather-up the face of the female unit of the socket connector) with high temperature dielectric grease.

Conductive grease appears to be expensive, but you use such small amounts that an 80 gram tube could last a lifetime.

Since you won't be 'dropping the stick' again until next Fall, you don't want to have a problem develop mid-season, and with an anchor light you can't easily check whether it's working or not. And, since you're doing so much other work, Bruce, this few minutes of additional care is certainly worth the effort. It's also a very good thing to do on electronic connections like coax connectors.

While you're at it, it's a good idea - especially in a salt-air environment - to spread some dielectric grease over all of the wiring connections. If there's no sign of corrosion at a connection it may not be necessary to disconnect it, just slather the grease all around the joint between the screw and the terminal. If a connection is just wire under a screw head it might be a good idea to take it apart and replace it with a crimp-on ring connector, and grease it up well (I like to put conductive grease inside the connector before inserting the wire, and a thin film of conductive grease on both sides of the ring, and then I grease-up the finished connection with dielectric grease).

By the way, all of the above applies to brand-new connections as well as to maintaining existing connections.

So, while you've got the opportunity, Bruce, I'd encourage you to do a little preventative maintenance on the electrical and electronics connections. With everything else you're doing it's evident that you don't shirk from doing what needs to be done. Now that you've shamed/motivated me into action maybe I'll get a few things done today myself...

...if the breeze doesn't come up.

The trouble with a destination - any destination, really - is that it interrupts The Journey.

Lee Panza
SR/SK #2134
San Francisco Bay
(Brisbane, CA)

Edited by - on

Stinkpotter
Master Marine Consultant

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Djibouti
9013 Posts

Response Posted - 03/30/2014 : 09:14:48

Lee, I've been advised to spray down my electrical connections with something like T-9, CRC 656, or Corrosion-X. Is that a reasonable alternative to surgical grease-slathering? I've done it on things like bus-bars and behind electrical panels, in an attempt to get everything (including switch contacts), and I've seen mechanics do it inside outboards for general corrosion prevention, including on the electrical connections.

Any comments on that? Thanks for starting this topic!

Edited by - Stinkpotter on 03/30/2014 09:16:37

sdpinaz
Navigator

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USA
193 Posts

Response Posted - 03/30/2014 : 13:48:13

When you upgrade to crimp on ring connector instead of bare wire, should you solder it or crimp it? which is better?

Edited by - on

Stinkpotter
Master Marine Consultant

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Djibouti
9013 Posts

Response Posted - 03/30/2014 : 15:24:12

Recommendation: Sailboat Electrics Simplified by Don Casey. (...with all due respect to our resident experts.) I don't have my copy with me, so can't promise what it covers or doesn't, but it's the kind of reference I want when I'm messing around with something that can set my boat on fire. (As I've mentioned before, I was on one that had plastic smoke pouring out of the sail locker and galley cabinet, about ten miles out on the Pacific.

)

Edited by - on

pastmember
Master Marine Consultant

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2402 Posts

Response Posted - 03/30/2014 : 17:38:46

Burnishing contacts requires far less abrasion than most think. We used paper in the military to burnish relay contacts and it worked well, no increased surface area but corrosion "wiped" off. To a greater point though, is the festoon bulb and fixture the dumbest idea or what! They make me want tiny zip ties to compress the contacts against the bulb.

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Voyager
Master Marine Consultant

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5231 Posts

Response Posted - 03/30/2014 : 18:00:38

I'd recommend Don Casey's book to everyone, including the "experts". Learn something new every day.
Like Lee's description of the sandpaper damage. While his description makes perfect sense, you'd never intuit that - you'd just "shine it up and fageddaboutit". Polishing with finer and finer grit is a good idea and protecting the finish with grease is great.

And Lee, I apologize about anything …. It's April so my cabin fever takes control of my brain! Lots to do before splash. After that, Meh!

Edited by - on

islander
Master Marine Consultant

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3992 Posts

Response Posted - 03/30/2014 : 18:01:07

<blockquote id="quote">quote:<hr height="1" noshade id="quote"> is the festoon bulb and fixture the dumbest idea or what! They make me want tiny zip ties to compress the contacts against the bulb.<hr height="1" noshade id="quote"></blockquote id="quote">
DITTO! Especially the mast head light.
This is great corrosion inhibitor. I've used it for years on electrical connections/panels etc.

Edited by - on

redeye
Master Marine Consultant

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3474 Posts

Response Posted - 03/31/2014 : 04:00:47

I sprayed crc dielectric grease directly into my fuses and switches last week. It leaves a white residue I had to wipe down, ( teflon I'd guess ) The switches seemed much happier. Sprayed down the back of the panel also.

Those new heat shrink sleeves on the crimp connectors are referred to as adhesive now... ( some of them at west marine )
Good crimpers and those heat shrink sleeves are the way to go.
Expensive... but They rock.

<< To a greater point though, is the festoon bulb and fixture the dumbest idea or what! >>

I've about decided the festoon bulb setup was designed to be self cleaning, it vibrates and moves so much. Can't tell you how many times I've seen a bulb not working, and you whack it and it comes on.

Edited by - redeye on 03/31/2014 04:18:42

Lee Panza
Captain

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USA
465 Posts

Response Posted - 03/31/2014 : 08:06:42

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by sdpinaz
 When you upgrade to crimp on ring connector instead of bare wire, should you solder it or crimp it? which is better?
<hr height="1" noshade id="quote"></blockquote id="quote">
Scott, I'm gonna presume you're asking that as a bona-fide request for advice, but that question - "solder or crimp" - is about as provocative in some circles as "what's the best anchor" can be among sailors. When I was looking into that question myself a few years back I read some pretty intense arguments on other forums, especially among ham hobbiests.

There're pros and cons to both, but crimping (with a good ratchet-style crimper) along with sealing both ends of the tube on the connector (heat-shrink AND 'liquid electrical tape') seems to be more than adequate. And it's a lot less demanding of expertise than making really good soldered connections.

Any kind of dielectric coating on the outside of a connection would be a good idea; I use high-temperature grease at lightbulbs because of the heat they generate, but just about anywhere else it's not an issue. Dave, I use T-9 as a lubricating anti-seize on my turnbuckles, but it hadn't occurred to me to use it on electrical terminals. It leaves a little bit of greasy residue (which is why bicyclists argue against using it on their derailleurs because it picks up grit, but that's not an issue on a sailboat), so it would seem like a good idea. I haven't checked the resistivity of any other products, but I'm sure any that are marketed specifically for their insulating properties (especially if they're marked "marine" like the CRC product that Scott posted) would be fine.

It just can't be over-emphasized how important it is on a boat, especially in a salt-water environment, to use extra precautions with all electrical and electronic connections. I'm glad to see the other suggestions being posted here (I was afraid this thread would be ignored as only being of interest to the geeks among us).

[edit: I still think, however, that applying a semi-solid grease inside a pin-and-socket connector - like the thru-deck fittings - is better than just spraying something on the outside of the closed joint.]

Edited by - Lee Panza on 03/31/2014 08:10:04

sdpinaz
Navigator

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USA
193 Posts

Response Posted - 04/01/2014 : 11:08:55

RE: Solder or Crimp...
Thanks Lee,
I had no Idea what can of worms I could open with that! People are pretty adamant one way or another, who woulda thunk.
Since I asked the Q, I have been looking online for the answer and I have realized it is not a straighforward answer. It all depends on so many variables: Location of connection,, amount of fatigue the connection is expected to encouter, condition and quality of original wire, quality of ring connector, quality of solder if used, condition of the rest of the DC circuit( this once is a huge variable), competence of the solderer, and maintenance/inspection schedule after the solder job....ect,ect.
Wow I had no idea.
Anyway the ABYC standards are to have a mechanical connection in addition to a soldered conection incase of an overloaded or shorted wire that heats up enough to remelt the solder (makes sense), and shrink-tape is not enough. Also if any solder wicks into the stranded wire past the connector it makes the wire stiff and brittle and can potentially break due to fatigue in that spot. The benfits of solder is that it seals the connection better and can lead to reduced corrosion due to wicking of moisture and salts into the stranded wire, there is also more contact and therefore less resistance between the wire and the connector than in just a crimp.

After reading what I have, on my boat I would not solder, especially at the top of the mast like this repair where the fatigue could be great and the inspection schedule not so frequent, and especially since I am not as proficient as needed with a solder gun
Anyway, who knew.....

Edited by - on

Lee Panza
Captain

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USA
465 Posts

Response Posted - 04/01/2014 : 19:56:59

Ya see what I mean, Scott?

I think the greatest factor that would tip the argument for us is how finicky solder can be. On a boat - with contacts and/or wires that have already gotten exposure to the oxidizing elements, and working in physically challenging spots - getting good soldered connections can often be a lot more difficult than back home on the bench. Add to that the challenge of heating both the connector and the wire just enough to flow the solder, but not enough to melt insulation or adjacent components, and one might well not wind up with connections that resemble the illustrations in a book by Don or Nigel. I freely confess that I never do. Then there's also the chemistry of soldering, using the right kind of flux and solder (never acid-core!). All in all, I would prefer to crimp rather than solder pretty much wherever I could.

Interestingly, the one place (other than inside closed-box electronic devices) that I would consider solder - and for exactly the opposite of one of the reasons why you'd avoid it - is on or attached to a gas or diesel motor. It's true that wicking solder can create a stress-concentrator at the point that it stops its intrusion, but that's only an issue of there's an unsupported sag of wire beyond that to bounce around and cause flexing to occur at that point. If the wire is properly supported I don't think that's an issue to be concerned about. On the other hand, if a crimped connection is not well-made I'd think the continuous vibration of a reciprocating engine could eventually weaken it to the point that the wire falls out of the connector.

Bottom line, with either approach, is that electrical connections need to be made with care and should be inspected from time to time. I'll bet there aren't many Cat-25 owners that have crawled all the way into the dumpster lately to inspect the back of the factory-installed panel. However, I have seen some nicely made custom panels, including a few shown on this forum, that are easily opened (often on hinges). But having it easy to open doesn't help if one never does open it for an occasional inspection.

Anyway, I'm glad to read that you're looking into this carefully, Scott. Good luck with the work.

Edited by - on

Dave5041
Former Mainsheet Editor

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USA
3754 Posts

Response Posted - 04/01/2014 : 21:46:59

The heat shrink adhesive connectors aren't just a name change. The shrink tubing is coated internally with a thermal adhesive to stick to the insulation. Expensive, but a great product. I used to coat the insulation wit liquid electrical tape, crimp, shrink, and the seal both ends with liquid ET. Now, I just seal the the open end.

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redeye
Master Marine Consultant

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3474 Posts

Response Posted - 04/02/2014 : 12:01:01

<< thermal adhesive to stick to the insulation. Expensive, but a great product >>

I was impressed, never used it before and the older heat shrink seemed a bit underwelming. This new adhesive heatshrink is cool...

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Voyager
Master Marine Consultant

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USA
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Response Posted - 04/02/2014 : 19:52:37

Only location I would use solder on a boat - the VHF connector - center conductor of the wire into the center conductor of a male plug connecting to the VHF radio and to the VHF antenna. Shakespeare offers a solder-less connector for this purpose, however I have not tried to use one. Might be ok, but I have used the solder connector with good results. Should be noted that the VHF plug body holds the cable securely in place so the solder connector is not under vibration or bending stress.

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