CCA wire vs OFC wire, my experience

Well, here it is:

I'm a little bemused by this

Aluminium wire is crap, everyone knows that - and what's with the 'oxygen free' rubbish, that's just a marketing term used by HiFi advertisers to con the gullible.

I agree that the audio market use of the term is 101% marketing ploy.

However oxygen-free copper is a real entity and has some desirable characteristics:
https://en.wikipedia.org/wiki/Oxygen-free_copper
https://www.twi-global.com/technica...ty-of-materials-copper-and-copper-alloys-023/

Albeit, on this forum we are unlikely to be discussing welding it.

John

Nigel Goodwin said:

I'm a little bemused by this

Aluminium wire is crap, everyone knows that - and what's with the 'oxygen free' rubbish, that's just a marketing term used by HiFi advertisers to con the gullible.

Click to expand...

If everyone knew that then there wouldn't be such a large market for it, would there?

That length of wire of that cross section should be <5 mΩ in aluminium, and <3 mΩ in copper. At 6 A the heat dissipated should be <0.2 W with aluminium and < 0.1 W with copper.

Those resistances and powers are completely irrelevant compared to the imperfections in the terminations. The fact that the copper wire has a resistance of 12 mΩ shows that the termination resistance is larger in the real world.

Anyone who is trying to save fractions of a penny on 5 cm of wire by using CCA instead of copper, or who is trying to hide that the wire is cheap by using CCA which is fatter for the same resistance, isn't going to be making the connections properly. It could also be that the wire had been bent too much on installation, and aluminium would crack strands more easily than copper.

Aluminium has its uses in conductors. Some cars where the battery is in the back have an aluminium conductor to go to the starter motor. Aluminium is less than twice the resistance for the same area, so under twice the volume needs to be used. However, aluminium is less than a third of the density of copper, so it ends up at just over half the weight of the copper. (values from Wikipedia). Obviously the insulation is larger so it weighs more to insulate the aluminium, but the larger cross section and lower weight means that the conductor needs fewer supports. Also in car construction, the connectors are put on to the conductors using the right tooling and techniques, so bad connections aren't likely.

Diver300 said:

That length of wire of that cross section should be <5 mΩ in aluminium, and <3 mΩ in copper. At 6 A the heat dissipated should be <0.2 W with aluminium and < 0.1 W with copper.

Anyone who is trying to save fractions of a penny on 5 cm of wire by using CCA instead of copper, or who is trying to hide that the wire is cheap by using CCA which is fatter for the same resistance, isn't going to be making the connections properly. It could also be that the wire had been bent too much on installation, and aluminium would crack strands more easily than copper.

.

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That wasn't the reason, there is a lot more of that wire used in the application as it was selected based on specified conductivity. HOWEVER, galvanic corrosion and thermal stresses introduced by dissimilar metals in heat generating electrical contact are not in the wire specs and appear to be significant. Notably I am seeing levels of corrosion across all the CCA installations which imply it's probably best to avoid using it in PWM apps.
To clarify, while the average current may be 6A, the wire was carrying PWM of around 15 to 18A.

The only use of CCA wire I used was for RG-6 which was copper clad aluminum. I got 1000' of it for free. Honestly, I did not realize it was CCA until much later. It is a slight issue because the rotor I use is powered from an RG-6 cable. RF is going to travel along the skin anyway.

Mosaic said:

If everyone knew that then there wouldn't be such a large market for it, would there?

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What makes you think there is?

I don't know as you can even buy aluminium wire in the UK?, with perhaps the exception of 300KV cables for pylons, which often use aluminium for weight and cost reasons.

Lots of producers/suppliers = demand:

https://www.alibaba.com/showroom/copper-clad-aluminum-wire.html

The U.K. doesn't represent a sampling of the World markets.

>>
Alibaba.com offers 24,256 copper clad aluminum wire products. About 96% of these are electrical wires. A wide variety of copper clad aluminum wire options are available to you, such as bare, insulated. You can also choose from solid, stranded. As well as from pvc, enameled, and rubber. And whether copper clad aluminum wire is heating, overhead, or underground. There are 24,214 copper clad aluminum wire suppliers, mainly located in Asia. The top supplying countries are China (Mainland), India, and United States, which supply 99%, 1%, and 1% of copper clad aluminum wire respectively. Copper clad aluminum wire products are most popular in South America, Eastern Europe, and North America. You can ensure product safety by selecting from certified suppliers, including 6,955 with ISO9001, 2,689 with Other, and 854 with ISO14001 certification.<<

Mosaic said:

Lots of producers/suppliers = demand:

https://www.alibaba.com/showroom/copper-clad-aluminum-wire.html

The U.K. doesn't represent a sampling of the World markets.

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No, but we probably have the worlds best electrical system - which probably explains the lack of aluminium wire

Did you fit the original wire?, and if so WHY??? - why would anyone with even a slight knowledge of electronics/electrics use a massively sub-standard product?.

Assuming you didn't fit it, presumably you didn't know it was there? - or you would probably have replaced it, with something more suitable, before it failed.

I notice the list of countries you mentioned are all well known for their fairly poor electric systems

There's also some secondary fallout from the metal corrosion shed from the CCA wire. Notice the zinc plated 6-32 MOSFET screw has started to corrode as well. The MOSFET next to it (with the good screw) carries the identical current as one of the series pair is configured as a drain to source polarity limiter.