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From: A Jensen (no email)
Date: Sun Aug 01 2004 - 14:21:44 EDT
Rich Gano wrote:
As an alternative to what I consider the overkill of tinned 2/0 marine grade
battery cable, I went to a local battery shop with my old welding cables and
had them duplicate them in standard non-tinned, 2/0 battery cable.
>>>snip<<<
- "The best is the enemy of good enough."
I think it applies well in this case. My good enough battery
cables will be just as shiny, maybe shinier, when opened in fifty years as
the tinned marine grade
REPLY
I agree with what Rich says. However there is one possible instance wher
tinned wire is superior.
On twin engined boats the should be a heavy cable joining the two engine
blocks together.
this is necessary for when an emergency start requires joining or crossing
the start battery banks together.
About the only possible location for this cable is to run it underneath the
floor boards installed between the two engines.
This places the cable very low in the bilge and if th eboat has any water
in the bilge this cable wil become submerged from time to time.
PVC insulation is NOT impervious to water when submerged for any lenght of
time.
It is this aspect which justifies the use of tinning in better grades of
wire.
Secondly, elevated temperatures causes the plasticizer used to make PVC
flexible to evaporate.
This is why old wire in the engine room is brittle and the insulation cracks
when flexed.
If the insulation flexes and cracks, this allows moist salt laden air to
enter the cable and migrate along the surface of the wire. If the wire is
not tinned, corosion is much more rapid than when the wire is tinned.
This is the technical justification for tinning.
Type 3 stranding is the finest stranding available in cable.
Type 1 is the most coarse. This is what you usually find in stranded house
wiring suych as stoves and dryers.
Type 2 standing is what yuo normally find in automotive applications, except
for such cables as battery leads that go from chassis to the engine which is
flexibly mounted to dampen vibration.
Boats are a class of vehicle and thus subject to varying amounts of
vibration.
This is the basis for arguing that boat wiring must be flexible. ANCOR has
taken this one step further and is promoting the use of Type 3 stranding
for all boat applications. When the cable is firmly clipped in place every
18 inches ther is litel or no movement.
The combination of type 3 stranding and having these strands tinned is their
justification for the very high price charged for "marine" cable. Good
marekting approach - if you can convince gullible consumers..
However, many industrial applications are even more severe and also requires
flexibility and tinning.
Diesel electric locomotivea are a case in point.
The electric motors are mounted directly on the wheel axels. The generator
is mounted on the frame chassis.
Very flexible cables are needed to jumper the gap from fixed generator to
the moving wheels.
In addition, these cables are out in the open where they are subjected to
strikes from flying ballast stone chips, grit from the brake pads, dripping
diesel fuel and grease from the wheel axel lubricant and extremes of
temperature.
All in all a much more hostile environment than most boats offer.
This is why a lot of reputable installer shops now use DL ( diesel
locomotive) grade cable for the larger size 1/0 to 4/0 cables. Some of the
manufactures of DL cable are now getting their cable certified by UL for
marine application.
Remember it is UL not ABYC that does the actual certification.
regards
Arild
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