wire conductivity

using http://www.powerstream.com/Wire_Size.htm

is there a functional difference, other factors ie metal purity equal,

between 8-12-14> gauge wire having 10 strands and 25 strands ?

does covering each copper strand with aluminum coating increase conductivity ?

or increase conductivity eliminating corrosion ....

 

[pfjw@aol.com]

On Friday, January 6, 2017 at 9:52:54 AM UTC-5, avag...@gmail.com wrote:

>>SNIPPAGE<<

a) Wire conductivity, irrespective of material, is a function of surface area and gauge amongst other factors. So, if 14-gauge wire is then divided into strands, the final product with the most strands will have the most surface area, and so by some factor greater conductivity.

b) Using material conductivity hierarchy, the most conductive material wants to be on the surface. Aluminum is a much poorer conductor than copper. All other things being equal, aluminum coated copper will be a poorer conductor than copper-coated aluminum (or steel: c.f. CopperWeld).

c) Corrosion is a factor, but not much of one. Alumina (AKA Aluminum Oxide) is an excellent insulator, as well as being quite inert. As aluminum wire acquires an oxide coating very nearly immediately upon exposure to air, that will reduce conductivity on the immediate surface of the wire. But as that coating is only a very few nanometers thick, the effect is near-zero overall. Copper oxides and sulfates as well as various other 'salts' are variously conductive, but also can be rectifiers, so there will be some effect on overall conductivity in the presence of these materials. BUT, copper is not a very active metal, so oxidation under normal atmospheric and environmental conditions is low and slow. Similar to Aluminum, but for different reasons.
d) Electrolysis is always a factor when dissimilar metals are forced into a conductive connection in the presence of oxygen or other oxidizers. For an interesting experiment, take an ordinary 16D nail, wrap a bit of copper wire around it, and place it in a glass of ordinary tap water. In an adjacent glass place a similar nail, no copper. Then a bit of copper, no nail. Do the same with an aluminum wire bonded to a copper wire (mere wrapping may not insure sufficient connectivity for electrolysis to take place. Copper clad materials generally do not suffer as there is very limited surface area exposed.

Enjoy!

Peter Wieck
Melrose Park, PA

 

[pfjw@aol.com]

On Friday, January 6, 2017 at 2:32:01 PM UTC-5, John Robertson wrote:

At 60 Hz in copper, the skin depth is about 8.5 mm, slightly thicker
than gauge 0.
You are talking about skin effect which is only starts to show above a
few kilohertz, otherwise the raw diameter of the wire is what carries
the current. Multi-strand wire (such as power cords, or speaker wire) is
convenient as it flexes, but it carries no more current than an
equivalent solid core wire at frequencies under around 10kHz. For
transmission towers where the outer diameter of the wire is much larger
that 8.5mm dia, then uses multi-stranded wire to get around it.

In the words of the prophet: Yabbut!! (Yes, but!)

Most discussions around wire material and types wind up, at least at some point, around speaker wire discussions. Hence the reference to surface area being an advantage. Speaker wires commonly carry in the multi-kHz frequencies.

For normal household use the difference will be negligible, and in some specific conditions actually favor solid conductors. And to be a tiny bit snarky: "There is a formula for that".

My specific choice for speaker wire is #12 19-strand THHN wire chucked and twisted in a drill for easier handling. Quite manageable and extremely tough.

Peter Wieck
Melrose Park, PA

 

they just flip out

electrical current, here 12v+ DC in an auto primary wire does not seek the least obstructive path that is at the interface of copper n aluminum cladding ?

 

[John Robertson]

On 2017/01/06 7:17 AM, pfjw@aol.com wrote:

On Friday, January 6, 2017 at 9:52:54 AM UTC-5, avag...@gmail.com wrote:

SNIPPAGE

a) Wire conductivity, irrespective of material, is a function of surface area and gauge amongst other factors. So, if 14-gauge wire is then divided into strands, the final product with the most strands will have the most surface area, and so by some factor greater conductivity.

At 60 Hz in copper, the skin depth is about 8.5 mm, slightly thicker
than gauge 0.
You are talking about skin effect which is only starts to show above a
few kilohertz, otherwise the raw diameter of the wire is what carries
the current. Multi-strand wire (such as power cords, or speaker wire) is
convenient as it flexes, but it carries no more current than an
equivalent solid core wire at frequencies under around 10kHz. For
transmission towers where the outer diameter of the wire is much larger
that 8.5mm dia, then uses multi-stranded wire to get around it.

b) Using material conductivity hierarchy, the most conductive material wants to be on the surface. Aluminum is a much poorer conductor than copper. All other things being equal, aluminum coated copper will be a poorer conductor than copper-coated aluminum (or steel: c.f. CopperWeld).

If you are comparing wire coated with aluminum vs a copper wire of the
same diameter as the coated, then yes, the plain copper would conduct
more current.

c) Corrosion is a factor, but not much of one. Alumina (AKA Aluminum Oxide) is an excellent insulator, as well as being quite inert. As aluminum wire acquires an oxide coating very nearly immediately upon exposure to air, that will reduce conductivity on the immediate surface of the wire. But as that coating is only a very few nanometers thick, the effect is near-zero overall. Copper oxides and sulfates as well as various other 'salts' are variously conductive, but also can be rectifiers, so there will be some effect on overall conductivity in the presence of these materials. BUT, copper is not a very active metal, so oxidation under normal atmospheric and environmental conditions is low and slow. Similar to Aluminum, but for different reasons.

Of course corrosion will show up as a problem at connection points, but
rarely does it matter for regular wire. Battery leakage though was a big
problem with electronics designed in the 70s to 90s - but that mostly
affect circuit boards and the connectors to them. Battery and salt are
factors for wire corrosion in vehicles.

> d) Electrolysis is always a factor when dissimilar metals are forced into a conductive connection in the presence of oxygen or other oxidizers. For an interesting experiment, take an ordinary 16D nail, wrap a bit of copper wire around it, and place it in a glass of ordinary tap water. In an adjacent glass place a similar nail, no copper. Then a bit of copper, no nail. Do the same with an aluminum wire bonded to a copper wire (mere wrapping may not insure sufficient connectivity for electrolysis to take place. Copper clad materials generally do not suffer as there is very limited surface area exposed.

Interesting. Thanks. The results probably depend on the hardness of your
water...

Enjoy!

Peter Wieck
Melrose Park, PA

Indeed, have a good day!

John :-#)#

--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

 

[Dave Platt]

In article <65b7626d-4679-4d55-8177-5e20db49635f@googlegroups.com>,
pfjw@aol.com <pfjw@aol.com> wrote:

In the words of the prophet: Yabbut!! (Yes, but!)

Most discussions around wire material and types wind up, at least at some point, around speaker wire discussions. Hence the reference to surface area being an
advantage. Speaker wires commonly carry in the multi-kHz frequencies.

Yup. But, my recollection is that the "surfaces" of the individual
wire strands are almost irrelevant for speaker wire. The strands are
packed together, and are in frequent-enough electrical contact with
one another that they behave electrically in a way very close to that
of a solid wire. You don't get an additional "skin effect"
conductivity win from the individual "skins" of the individual
strands.

So, high-audio-frequency performance tends to be influenced more by
the bulk inductance of the cable than by the solid/stranded issue.
Using four conductors in a "four-cross" confirmation can help with
this.

>My specific choice for speaker wire is #12 19-strand THHN wire chucked and twisted in a drill for easier handling. Quite manageable and extremely tough.

Sounds like a good economical choice.

 

[Phil Allison]

avag...@gmail.com wrote:

using http://www.powerstream.com/Wire_Size.htm

is there a functional difference, other factors ie metal purity equal,

between 8-12-14> gauge wire having 10 strands and 25 strands ?

** Yes, stranded wire is far more flexible.

does covering each copper strand with aluminum coating increase
conductivity ?

** Aluminium wire is often coated in copper, not the other way around.

It improves conductivity and most importantly makes it possible to solder the ends.

Sometimes it is passed off as being pure copper to the unwary.



..... Phil

 

[Jon Elson]

pfjw@aol.com wrote:

On Friday, January 6, 2017 at 9:52:54 AM UTC-5, avag...@gmail.com wrote:

SNIPPAGE

a) Wire conductivity, irrespective of material, is a function of surface
area
Shouldn't that be CROSS-SECTIONAL area?
and gauge amongst other factors. So, if 14-gauge wire is then divided
into strands, the final product with the most strands will have the most
surface area, and so by some factor greater conductivity.

Yes, but actually, I think the conductivity is better with FEWER strands of
thicker wire. Many strands of tiny wire ends up being a lot of air and not
so much copper.

As for the original poster, that silvery coating on typical stranded wire is
tin or solder, NOT aluminum. It is there mostly to make the wire
solderable, but also acts as a corrosion inhibitor.

The only aluminum wire is used as power lead-ins to houses, as it is much
cheaper than copper. They did use aluminum wire INSIDE houses in the US
around 1966-1968, and it burned a lot of houses down, due to the cold flow
of aluminum weakening the contact force.

Jon

 

On Friday, January 6, 2017 at 9:01:07 PM UTC-5, Phil Allison wrote:

avag...@gmail.com wrote:


using http://www.powerstream.com/Wire_Size.htm

is there a functional difference, other factors ie metal purity equal,

between 8-12-14> gauge wire having 10 strands and 25 strands ?



** Yes, stranded wire is far more flexible.


does covering each copper strand with aluminum coating increase
conductivity ?


** Aluminium wire is often coated in copper, not the other way around.

It improves conductivity and most importantly makes it possible to solder the ends.

Sometimes it is passed off as being pure copper to the unwary.



.... Phil

accessed the specs via 4 lines of ID codes.....copper inside, aluminum coating outside, 25 strands Ga 12 has a mil spec rating

difficult scraping the silver off with a new utility blade

 

[Phil Allison]

avag...@gmail.com wrote:

does covering each copper strand with aluminum coating increase
conductivity ?


** Aluminium wire is often coated in copper, not the other way around.

It improves conductivity and most importantly makes it possible to
solder the ends.

Sometimes it is passed off as being pure copper to the unwary.




accessed the specs via 4 lines of ID codes.....copper inside,
aluminum coating outside, 25 strands Ga 12 has a mil spec rating

** Kindly post in plain English - not pure gibberish like the above.

I have never heard of Aluminium clad Copper wire and neither has Google.

Where have you ?


..... Phil

 

[Ralph Mowery]

In article <N5ydneYpyOkclO3FnZ2dnUU7-dvNnZ2d@giganews.com>,
jmelson@wustl.edu says...

As for the original poster, that silvery coating on typical stranded wire is
tin or solder, NOT aluminum. It is there mostly to make the wire
solderable, but also acts as a corrosion inhibitor.

The only aluminum wire is used as power lead-ins to houses, as it is much
cheaper than copper. They did use aluminum wire INSIDE houses in the US
around 1966-1968, and it burned a lot of houses down, due to the cold flow
of aluminum weakening the contact force.

Jon

I got some wire of 16 and 12 guage to use for 12 volt power wiring. It
may have been called speaker wire. A red and black pair.
The wire turned out to be aluminuim with a coating of copper.

I have seen some coax where the center conductor is aluminum with a
coating of copper, but this is for use at radio frequencies where the
skin effect is very much in effect.

 

[Phil Allison]

Ralph Mowery wrote:

I got some wire of 16 and 12 guage to use for 12 volt power wiring. It
may have been called speaker wire. A red and black pair.
The wire turned out to be aluminuim with a coating of copper.

I have seen some coax where the center conductor is aluminum with a
coating of copper, but this is for use at radio frequencies where the
skin effect is very much in effect.

** Copper clad aluminium wire ( aka CCA ) is commonly used for loudspeaker voice coils - enamel coated of course.

The advantage is lower weight compared to pure copper, leading to more dBs per watt.


..... Phil

 

>"The advantage is lower weight compared to pure copper, leading to more dBs per watt. "

Depends on the application, the advantage might be negligible. The mass will certainly matter more at higher frequencies, so these big massive cones on speakers in sound reinforcement bass bins might not benefit quite so much as say a woofer in a decent quality two way home speaker.

I also have heard of copper clad aluminum wire for other purposes and usually it is to save money. One instance it is wires strung from telephone poles. Alot of that is copper clad steel for the tensile strength, again because of cost but not just the cost of the copper, they can put up longer spans and have to set less poles.

I can't think of much reason for aluminum clad copper.

 

A quantity of aluminum tineed or clad (?)
Material online but not specifically answering my question beyond the general rules of surface conduction.

An absence, in a brief surface read, led to a conclusion there's not a serious difference tween copper m aluminum clad copper. An original patent sez there is a layer of silver molecules between...in 1956, WE.

And the advantage is the AL clad wire is less reactive to insulation at higher temps.

Last question: when soldered is the joint as conductive as copper solder copper ?

Silver melts streams off solder joins copper copper with a low % aluminum.

I used the new aluminum clad wire giving a less conductive result but there are other available reasons for the result so a redo. Maybe a direct conparison.

 

no, in the 1930's rubber insulation decayed against copper so cladding was produced. Aluminum cladding ( I read this last night ) did not adhere to copper but the Westinghouse patent covering copper with silver produced a functioning AL outer layer .....for lower temps on the surface or greater resistance to degradation from outside heat sources...I'm not sure which or both.

Thus, with a fine multiple strand wire there is more conductivity, less degradation more flex with a smaller space occupation. Maybe more effective bundling ?

that's what the material suggests. I read the answer to my question of not flowing thru less resistance toward the center of a copper wire with a thicker AL cladding as the outer areas of conductivity are geometrically larger supplying more free electrons in this Cu AL apparently topping more conductive copper below.

now tell me why that wire is more resistive ? as per common knowledge.

 

[John Robertson]

On 2017/01/07 4:44 AM, avagadro7@gmail.com wrote:

A quantity of aluminum tineed or clad (?)
Material online but not specifically answering my question beyond the general rules of surface conduction.

An absence, in a brief surface read, led to a conclusion there's not a serious difference tween copper m aluminum clad copper. An original patent sez there is a layer of silver molecules between...in 1956, WE.

And the advantage is the AL clad wire is less reactive to insulation at higher temps.

Last question: when soldered is the joint as conductive as copper solder copper ?

Silver melts streams off solder joins copper copper with a low % aluminum.

I used the new aluminum clad wire giving a less conductive result but there are other available reasons for the result so a redo. Maybe a direct conparison.

Is there a potential problem with clad wire in temperature extremes?
Will the layers shed in extreme (-40C) cold or heat (100C)? Or is that
not extreme enough?

Just asking...

John

 

[Phil Allison]

jurb...@gmail.com wrote:

"The advantage is lower weight compared to pure copper, leading to
more dBs per watt. "

Depends on the application, the advantage might be negligible.

** So what? If make no odds then makers use plain copper.

JBL have been using aluminium wire on their instrument speakers for many decades to increase efficiency. CCA is easier to work with and solder.



..... Phil

 

[isw]

In article <231306ca-50e4-45c6-a91b-bd3d60812c89@googlegroups.com>,
"pfjw@aol.com" <pfjw@aol.com> wrote:

On Friday, January 6, 2017 at 9:52:54 AM UTC-5, avag...@gmail.com wrote:

SNIPPAGE

a) Wire conductivity, irrespective of material, is a function of surface area
and gauge amongst other factors.

It's mostly a function of cross-section area at DC. As frequency rises
and skin effect begins to be important, surface area starts to matter,
so more, finer strands might be better, *but only if the individual
strands are insulated from each other*.

Isaac

 

[isw]

In article <N5ydneYpyOkclO3FnZ2dnUU7-dvNnZ2d@giganews.com>,
Jon Elson <jmelson@wustl.edu> wrote:

pfjw@aol.com wrote:

On Friday, January 6, 2017 at 9:52:54 AM UTC-5, avag...@gmail.com wrote:

SNIPPAGE

a) Wire conductivity, irrespective of material, is a function of surface
area
Shouldn't that be CROSS-SECTIONAL area?
and gauge amongst other factors. So, if 14-gauge wire is then divided
into strands, the final product with the most strands will have the most
surface area, and so by some factor greater conductivity.
Yes, but actually, I think the conductivity is better with FEWER strands of
thicker wire. Many strands of tiny wire ends up being a lot of air and not
so much copper.

As for the original poster, that silvery coating on typical stranded wire is
tin or solder, NOT aluminum. It is there mostly to make the wire
solderable, but also acts as a corrosion inhibitor.

The only aluminum wire is used as power lead-ins to houses, as it is much
cheaper than copper. They did use aluminum wire INSIDE houses in the US
around 1966-1968, and it burned a lot of houses down, due to the cold flow
of aluminum weakening the contact force.

ISTR that the problem was mostly that electricians couldn't be bothered
to learn the new techniques and so on that were mandatory to install the
stuff safely. It was only when it was installed just like Cu that it was
prone to overheating.

Isaac

 

On Saturday, January 7, 2017 at 11:21:52 PM UTC-5, isw wrote:

In article <231306ca-50e4-45c6-a91b-bd3d60812c89@googlegroups.com>,
"pfjw@aol.com" <pfjw@aol.com> wrote:

On Friday, January 6, 2017 at 9:52:54 AM UTC-5, avag...@gmail.com wrote:

SNIPPAGE

a) Wire conductivity, irrespective of material, is a function of surface area
and gauge amongst other factors.

It's mostly a function of cross-section area at DC. As frequency rises
and skin effect begins to be important, surface area starts to matter,
so more, finer strands might be better, *but only if the individual
strands are insulated from each other*.

Isaac

explain cross section electron availability for an aluminum/silver/copper wire or aluminum/copper where cladding cross section is thin ?