Conference unifix::sailing

    I'd scrape the sockets until I had shiny metal, and replace the bulbs.
    Then, not knowing which of the two alternatives is better, try the
    following experiment:  (1) coat the tip of the bulb and all the metal
    surfaces with grease to keep moisture out; or (2) use No-Ox which is a
    grease which I believe has a sacrificial metal mixed with it.
    
    I've used No-Ox on Cu-Cu connections before and it seems to work well, but
    I'd like to see a controlled experiment comparing it with ordinary bearing
    grease or white grease.
    
    On getting high resistance with no current flowing or low resistance
    with high current flowing:  this is due to an oxide barrier that has
    formed at some contact interface somewhere in the circuit from the
    +battery terminal back to the negative terminal.  When even a few tens
    of mA flow, the barrier is broken and low incremental resistance is
    obtained.  When the current is shut off, or if only microamps flow, then
    the oxide barrier causes it to look like an open circuit.  To get 2 V, there
    also has to be a shunt path due to corrosion, which is causing a voltage
    divider effect to occur.
    
    It sounds like you need to go through and redo much of your wiring.  I 
    suggest if you want it to last longest, solder all joints!  Crimping is
    also good, but will not last as long as soldered joints (you're talking
    3 years vs 6 years (for the soldered joint).
    
    The crux of it is that electrical joints have to be checked, and many
    redone, each season if you want a fully reliable electrical system.
    
    
    /Don
    

RE:.0 by BPOV04::T_MOORE

> One other strange thing, with master panal "on", light switch "on" I
> have 12 VDC at the socket, with master panel "on", light switch "off",
> I have about 2 VDC at the socket.  How come?????????

The switch is leaking a small amount of current (a fraction of a mA).  I'd 
wouldn't worry a lot about it as it is caused by salt on surfaces of the
switch.  You can "solve" it by carefully cleaning the light switch.  The
leakage would be back by next month if not sooner.


Your VOM has a resistance.  To find out the amount of current leakage,  find
out how many ohms per volt your meter is,  multiply that by the scale you
made the measurement on,  and then

   2V/R = current.

Example:  1K ohms per volt (a CHEAP VOM),  15 volt scale,  15K resistance,
Current = .13 mA

Example:  25K ohms per volt (a fair VOM),  15 volt scale,  375K resistance,  
currrent= .005mA.


Phil

re:                      <<< Note 1559.1 by WRKSYS::NELSEN >>>

Using grease in this application may cause trouble, unless the grease is
conductive. I believe that many lubricants are good insulators.

You may be able to obtain conductive grease at a good electronics store.
Make sure it's electrically conductive, not just thermally conductive (used for
mounting heatsinks!). 

--RS

RE:.3 by LANDO::SCHUMANN "Thanks for sharing that."

> Using grease in this application may cause trouble, unless the grease is
> conductive. I believe that many lubricants are good insulators.

Greases are generally good insulators.  When a connecters is assembled,  the 
physical wiping action will make a metal to metal connection even with the 
contacts coated with grease.  The grease will then keep salt water out of
the connection,  so it will stay a connection.  

I've used heat sink grease for this with very good results.  


Phil

    re .3 and .4, and my .2:
    
    The NoOx I referred to is the type grease that is sold in electrical stores
    for connecting Aluminum wire to Cu.  I've used it for connecting Cu to Cu
    on boats, but don't really know if it would be any better than ordinary
    bearing grease.
    
    My Volkswagen instruction manual suggests that all connectors should be
    filled with grease ...   Maybe it is as suggested in .4:  it is the wiping
    action that maintains the metal-to-metal connection, and the grease keeps
    moisture out.
    
    I tried measuring the resistivity of NoOx by putting the probes of my
    digital VOM into the grease.  The reading was an open circuit.  So it may
    be that that grease is NOT conducting, but rather the metal in it serves
    a sacrificial role in preventing electrolysis with the joint of two
    dissimilar metals.  In that case, I don't know how effective it would
    be with a Cu-to-Cu joint.  This is why I suggest trying an experiment
    with two lights in similar weather exposure:  one with NoOx (or equivalent),
    and the other with ordinary grease.
    
    Since these sockets corrode SO rapidly in wet conditions, it wouldn't hurt
    to try the experiment of packing it with ordinary grease.  If the connection
    opened up, one could wipe it clean and still be ahead of doing nothing.
    
    /Don
    
    

    	So far the only suggestion for cleaning the light sockets has been
    mechanical. My solution is to get some Muriatic Acid from your local
    Hardware store and carefully soak your corroded sockets. This should 
    be done with some care in a well ventilated area but the results are
    well worth it and, depending on the amount of corrosion to be removed,
    very quick. Just remove the socket and immerse it in a small amount of
    Muriatic, watch closely to see that only the rust is being eaten, and 
    remove and rinse thouroughly in clean water. Then dry and use one of 
    the corrosion preventive methods discussed eariler.
    	I use this method to clean the black oxidation that forms inside
    of the distributor caps on my cars. Also good for cleaning and
    descaling othe metals. 
    
    	Good luck , John 
     
    

    re .5:
    	The NoOx is NOT used, as you stated "for connecting Aluminum wire
    to Cu.".  It IS used to prevent/hinder the oxidation of the aluminum
    wire.  This happens quickly when copper is around.  The National
    Electical Code has very specific rules when dealing with AL wire. 
    The NoOx (I think its a brand name) is, I believe, non-conductive so 
    it will not help you make a better connection.  It should do a good 
    job of keeping the weather though.
    
    bjm