Terminal Block Confusion

[Joyride]

Gang,

I've been chasing down a gremlin low battery indicator when I transmit on the VHF  and determined that my issue was the ground...  I traced the wire back to behind the panel and found the negative terminal block with a severely corroded connection on one of the slots.  Does anyone know what to make of this.  The wire looks fine (not melted) but there is a lot of corrosion around that whole connection.  Any ides?  Also I'm not sure who installed this terminal block this way, but since all the circuits are "jumped" wouldn't it make more sense just to have bus bar? Thanks.   

[Stu Jackson]

1.  ...but there is a lot of corrosion around that whole connection.  Any ides? 

2.    Also I'm not sure who installed this terminal block this way, but since all the circuits are "jumped" wouldn't it make more sense just to have bus bar? 

jr,

1.  That happens altogether too often because the term strip is right below the vented stanchion for the head vent.  Leaks have been known to happen.  I've seen some boats where all the screws were corroded.  Mine are just fine.

2.  Yes, you're right, this is OEM.  Functionally the same thing as you know.

PS - If you add your boat info to your signature sometimes it helps us to help you.

[KWKloeber]

joy,

The reason why one machine screw corroded and not another is "who knows?"  It could be that the plating on that particular one was inferior so it got attacked first.  Not untypical,  but not a universal occurrence either.

Note that the jumpered terminal blocks are pretty typical for Catalina, not the best solution as you know.  CTY isn't known for it's "wiring expertise" -- ie., not the BEST in the industry, but certainly not the WORST either (I had a J/120 this year where in the OEM GFI receptacle box the hot wires were twisted together.  No, not wire-nutted, just twisted and taped.     

If a jumpered term block is used, it should be fed from the center, not the end. 

The typically "non marine" wire terminals are catalina normal also -- your rusted screw may be the least of the problems.  With those terminals you may find corrosion traveling all the way up one or more wires.  I had the saloon wiring corroded (ie, turned to green powder) for many feet inside the insulation due to the butt connectors CTY used.    Note that the fork a/k/a spade terminal are non-compliant because if the screw loosens they don't remain captive in the post.

ken

Gang,

I've been chasing down a gremlin low battery indicator when I transmit on the VHF  and determined that my issue was the ground...  I traced the wire back to behind the panel and found the negative terminal block with a severely corroded connection on one of the slots.  Does anyone know what to make of this.  The wire looks fine (not melted) but there is a lot of corrosion around that whole connection.  Any ides?  Also I'm not sure who installed this terminal block this way, but since all the circuits are "jumped" wouldn't it make more sense just to have bus bar? Thanks.

[J_Sail]

Both heat and galvanic action can contribute to corrosion. If that particular screw was slightly loose, then the contact interface can turn into a galvanic cell (two dissimilar metals with traces of water between). Also if the connection is carrying any significant current, the resistance caused by the loose connection causes localized heating. The two together *could* cause your corrosion. But as others said, it's often a mystery.

Once the plating is damaged I would recommend replacing the affected crimp terminals and abandoning that location on the block.

There is another recent thread on this board on contact lube / corrosion protection, but that is secondary in your case, as tight screw connections do not generally allow corrosion to progress into the actual electrical contact interface area.

[Joyride]

Thanks for the responses it looks like it must have been a loose connection leading to heat/corrosion.  I removed the terminal block and replaced but it was really only one of the connections that was bad.  I didn't see any signs of a leak nearby.  The jumper plate was almost corroded through as well and this could have caused some more grounding issues as all the circuits are connected through the jumpers so it would have isolated the top 4.  Any I also found a loose fitting on the panel and seem to have fixed the issue of the power loss on the vhf run. 

[Jim Hardesty]

FWIW   When Shamrock was surveyed he turned on every thing and pointed a led, non contact, thermometer gun at each of the connections on the terminal block.  Did the AC and DC separately.  Not sure if the test was real good, but it may show problems with the crimp or connection. 

Jim

[J_Sail]

An IR thermometer gun is useful for high-power continuously-on connections, but there are not many of those on a boat. It's much harder to spot problems with occasional-use loads that are below, let's say, 3-5 amps. The temperature increase from a circuit drawing less than that is not that great, the load may not be on when testing (some devices such as VHF radios, winches, windlasses, etc, only intermittently draw substantial power even with their breaker on). Also the physical size of the hot spot is much smaller than the area sensed/averaged by the IR thermometer.  More useful is an IR camera, but they are expensive and still can't easily catch bad connections on intermittent loads.

BTW, it's a really great idea to use an IR thermometer to take a baseline survey on ones engine, though for comparison periodically to spot problems. For $20 they are a nice tool to own. Once you buy one you will find myriad other uses for it around the house, too.

[Noah]

That all being said; Kudos to the surveyor for even looking behind the main electrical panel. Most do not, in my experience.

[Jim Hardesty]

For $20 they are a nice tool to own. Once you buy one you will find myriad other uses for it around the house, too.

That's my opinion.  I do check the terminal block most springs, along with the battery posts, stuffing box, and any thing else that comes to mind.  Only takes a few minutes and it may catch something early.

Jim

[Ron Hill]

Joy : I believe that Stu may be correct as that vented stanchion tends to leak (helpful dockhands tend to push and pull on it) breaking the bedding.

In the meantime as you look for that leak here's what I'd do:  I'd purchase a new negative terminal block (no need for the connection separators between connections on a negative block) and make a plastic flap to cover it from above while you chase and repair that leak.

A few thoughts

[Fred Koehlmann]

The vented stanchion behind the electrical is dangerous in my opinion. We almost had a fire behind there (see http://c34.org/bbs/index.php/topic,7030.msg47150.html#msg47150). 

I resolved that by venting the holding tank forward out the port side behind the port locker in the forward cabin. i then pull the stanchion, cut off the thru-hull bit, glass the desk closed and remounted the stanchion, but now it was just flush to the deck.

It's nice and dry in behind the electrical stuff now.

[KWKloeber]

Fred

OMG that's ugly.  Obviously the PO hasn't heard of ABYC E-11.14.
Those SOB's shouldn't be allowed on ANYTHING, including autos.

kk

[Fred Koehlmann]

Actually, that was Catalina wiring. Those connectors are throughout the boat, its just that in that location adding water to the mix was not useful. Anyway, that one's all fixed now.