Jim Alexander wrote:

REPLY
I'm replying to the list because Jim's situation is actually fairly common. Mostly it goes un-
noticed because few people bother to do detailed  voltage checks in the boat circuits.

The Perko switches will get coated with slight corrosion but the contact wiping action may not
remove all of it. Copper  oxide is actually a rectifier which drops 0.4 volts across the  junction.
Running current through the switch may in fact be sufficient to "burn off" this coating  thus
restoring the nominal  contact resistance.

This phenomenon is well known  in dry circuits  where the current flow is very low.
For this reason "dry circuit"  switches and contacts are usually gold plated to get around the
oxide problem.  For high power circuits, silver is also used since silver oxide is conductive.

Not all switches are made the same. Some of them have less contact pressure on the wiper arm.
This also contributes to the problem of voltage drop across the switch.
As a rule of thumb,  you should inspect and check all your main power  panel and cable
connections each year for tightness and corrosion build up. - in an ideal world that is! :-(

Also  check to make suer that  corrosion inside and under the insulation has not begun.
Last week I found a cable with  almost 10 inches of corrosion under what looked like perfectly
good insulation.

The very process of removing and reinserting a bulb will in fact wipe the bulb contacts enough to
provide a fresh  mating surface at a lower resistance.

And don't forget the  common crimp connection found at the end of every wire in the system.
The normal  insulated crimp die will not provide what is classed as a "gas tight"  joint.
The salt air will allow moisture to wick into the strands and over time some corrosion will build
up inside all these crimp joints.
More recently newer and better crimp connectors have become available but anything done more
than five years ago is not likely to fit in this category.

If you are going to  do detailed trouble shooting of this nature you have to measure the actual
current, know the actual wire lengths involved an then calculate the theoretical voltage drop
compared to the measured voltage drop.

Remember that  for navigation lights, ABYC allows only a 3% drop but for general lighting
circuits a 10%  drop is allowable.
Critical navigation instruments  should never be tapped into lighting circuits. They should have a
separate feeder of their own.  In practice, a  main feeder cable from the battery bank to the upper
helm station should be sized so that with everything  turned on at the same time, the voltage
drop in that feeder cable will not exceed 3%.
If that is the case then  it is allowable to split the power feed and supply both lighting and
navigation gear from the same power buss in the console.  A #2 cable  is often sufficient.

Cheers

Arild

x

across

Clarence,

I think I am making some real progress here and may have isolated the
problem?  At your suggestion I re-tested the Perko main switch and here is
what I found.  At "no load" I got 12.7 volts both in and out.
Then I put on a pretty small load, aft cabin lights, engine room lights,
etc.  With this relatively small load I got 11.2 volts in and 11.0 volts out
of the switch.  Whoops...........this indicated to me either the battery or
somewhere in between?  Quickly I got into the engine room and measured the
battery at the terminals with the load 12.5 volts.  Now my positive cable
comes off the battery and goes directly to a large Fuse and then the cable
picks up again and goes to the main panel & switch.  At the fuse I also got
12.5 volts in and 12.5 volts out.  So  seems to me the problem lies
somewhere in the cable between the fuse and the panel?  (the cables are
approximately 1/0 or 2/0 copper cables and the run is about ten feet)

My only question would be, can a bad ground cause this problem as well?

Jim Alexander

wire in the system.
The normal  insulated crimp die will not provide what is classed as a "gas
tight"  joint.
The salt air will allow moisture to wick into the strands and over time some
corrosion will build
up inside all these crimp joints.<<<<

Which is of course why these joints should be soldered.

Ideally tin the wire and the crimp fitting first, crimp on the fitting and
then flow the solder by heating the fitting with the iron. Alternatively bog
the joint up with soldering paste and flow that. Cover the joint with
heat-shrink tubing.

Dry joints are evil!

Regards, Robert Bryett
Sydney, Australia.
mailto:rbryett@mail.com

Jim Donohue wrote:

REPLY
Given that soldering will cause problems if improperly done, a better field connection approach is
to use a anti oxidant  paste in conjunction with crimping.
In the past year Ancor has been promoting the use of a paste which you smear onto the
stranded wire before inserting the wire into the crimp barrel or sleeve.
As you crimp;  the  paste is squeezed out from the tightly clenched wires, but remains in the
tiny air gaps between strands on both sides of the tightly crimped crush point.
This paste prevents corrosive salt laden air from getting to the wire strands and causing
corrosion.

Soldering can cause damage to insulation and if it wicks beyond the barrel will create a hard
point which will fail  if there is any vibration or repeated flexing.
This is why mil spec connectors now requires crimping instead of soldering. They learned the
hard way that soldered connections eventually have a nearly 100% failure rate.

regards

Arild

This is one of those pass the grain of salt situations.

A proper crimp done in a factory does not need and is not improved by
solder.  You just don't do any better than gas tight.  Solder immediately
opens up fatigue problems - the reason that we used stranded wire on boats.

If you are very careful and support every connection then crimp and solder
and heat shrink  is better for a field connection.  I would never solder in
a factory situation.

Note that ABYC leans toward crimp though they waffle.

Jim

Hello Jim,

Saturday, March 30, 2002, 9:59:15 AM, you wrote:

Sounds to me that the wiring from the breaker panel to the spreader
lights (at least) is too small - how much wire between port and
starboard light?

No lights = no current = no voltage drop.

--
Peter Bennett, VE7CEI    Vancouver, B.C., Canada
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver-webpages.com/van-ps

Brent Hodges wrote:>

REPLY
Ancor sells a small  1 oz tube of the stuff.  Looks the same as what I get in the industrial size
NOALOX  which I buy from Wesburne, an electrical wholesaler.
Ancor is selling convenience in small tubes,  they do not have a unique product solution.
That convenience comes at a price.  I pay twice as much for the industrial  size but get five
times as much paste.
Since NOALOX  is formulated to work with  wires it is safe to use on PVC insulation.
As I indicated earlier I do not know what if any reaction will happen  when you mix Corrrosion
Block and PVC insulation.

Cheers

Arild

From: "Arild Jensen" elnav@uniserve.com

smear onto the

(endsnip)

Is this a paste made by Ancor? Do you know the name of the paste? Sounds
like a worthy investment.

Brent Hodges