Using different types of wire in a system

System · March 2011

Is it OK to mix copper wire and aluminum wire in a system? Will electrolysis be an issue? Heres my scenario. Can I run 2/0 aluminum wire from my Tristar PWM TS-60 to my battery bank even though all other wires are copper? I am asking because 2/0 copper is like $4 a foot and 2/0 aluminum is $1 a foot.

Brianellul · March 2011

Re: Using different types of wire in a system

Eric R. wrote: »

Is it OK to mix cooper wire and aluminum wire in a system? Will electrolysis be an issue? Heres my scenario. Can I run 2/0 aluminum wire from my Tristar PWM TS-60 to my battery bank even though all other wires are copper? I am asking because 2/0 copper is like $4 a foot and 2/0 aluminum is $1 a foot.

Not sure about electrolysis, however remember that copper has a lower resistance than aluminium and therefore if you're going for aluminium cables make sure that you'll compensate for the extra resistance by using thicker cables.

waynefromnscanada · March 2011

Re: Using different types of wire in a system

Eric R. wrote: »

Is it OK to mix cooper wire and aluminum wire in a system? Will electrolysis be an issue? Heres my scenario. Can I run 2/0 aluminum wire from my Tristar PWM TS-60 to my battery bank even though all other wires are copper? I am asking because 2/0 copper is like $4 a foot and 2/0 aluminum is $1 a foot.

It can be safe, but there are unique and very real dangers. Definitely read and understand the information presented here:
http://www.faqs.org/faqs/electrical-wiring/part2/section-16.html
Oh, and Eric is correct, you will have to use a larger size aluminum wire due to increased resistance over copper, however, it can still be considerably cheaper.
Another information link: http://www.hsb.com/thelocomotive/Story/FullStory/ST-FS-ALUM.html

petertearai · March 2011

Re: Using different types of wire in a system

Hi When doing my electrical apprenticeship we used aluminium cable reticulating street lights . Special crimps were used to put copper tails an the ends of the aluminium,.Talk to your electrical supplier they should be able to advise. Possibly not a great saving on short runs, as from memory the special crimps were not cheep.
Regards Peter

mike95490 · March 2011

Re: Using different types of wire in a system

You can wire the alum wire directly to alum rated ckt breakers. I also used some splice blocks http://www.elecdirect.com/Data/ProductPDFs/C55-C57.pdf to tap into the middle of a feed, to convert from alum to copper, without a hydraulic crimper. Conductive goop MUST be used at aluminum connections.

Peter_V · March 2011

Re: Using different types of wire in a system

Eric R. wrote: »

Is it OK to mix cooper wire and aluminum wire in a system? Will electrolysis be an issue? Heres my scenario. Can I run 2/0 aluminum wire from my Tristar PWM TS-60 to my battery bank even though all other wires are copper? I am asking because 2/0 copper is like $4 a foot and 2/0 aluminum is $1 a foot.

There are a lot of potential problems with using aluminum wire and some of them don't pop up for several years. A lot of house fires were started because of aluminum wires that weren't correctly installed, or in some case WERE correctly installed

Is it really worth the hassle to save a couple dollars? Considering how much you've spent on the rest of the system?

System2 · March 2011

Re: Using different types of wire in a system

Thanks guys. This is exactly what I was afraid of. Im glad this forum exists. Very valuable info.

mike95490 · March 2011

Re: Using different types of wire in a system

Peter_V wrote: »

There are a lot of potential problems with using aluminum wire and some of them don't pop up for several years. A lot of house fires were started because of aluminum wires that weren't correctly installed, or in some case WERE correctly installed

Is it really worth the hassle to save a couple dollars? Considering how much you've spent on the rest of the system?

Aluminum wire has come a long way since the house fires in the 70's, new alloys, better connectors and conductive goop. Understanding the problem was half the battle!

For 3,000 feet of #6, it saved me thousands, now I'm getting ready to order 800' of #4, and 3,000 of #8. Big price difference when you have some long runs.

And copper is not without flaws either. 50 year old #10 wire oxidizes all the way through, and goes rotten. Aluminum only gets oxide on the outer layer, thus the conductive goop with sharp micro bits of something conductive to punch through the oxide.

waynefromnscanada · March 2011

Re: Using different types of wire in a system

mike90045 wrote: »

Aluminum wire has come a long way since the house fires in the 70's, new alloys, better connectors and conductive goop. Understanding the problem was half the battle!.

Agree. Much has been learned, many changes made and now aluminum is often used in new construction, especially with the larger wires from the panel to grid connections, with no problems at all. The key is education and following proper procedures to prevent problems. But it does scare the crap out of me when I hear electricians, who obviously have not updated their education on the subject, saying they treat aluminum exactly as they do copper, including any connections they make between copper and aluminum. My fear is that problems will result, and when they do, aluminum will be wrongly blamed.
By the way, I'm using aluminum on the 400 foot (800 ft return) run from my micro micro hydro to the batteries. Could not have afforded copper. Made the connections using the latest information available and have been keeping a close eye on things. Over 2 years now, and so far no sign of problems except at one connection I improperly made in the dampness down at the turbine which started to show signs of corrosion after one year. All other connections which were properly made, remain unchanged. Repaired and properly made that one connection and it remains like new. Why was that one connection improperly made in the first place? It had been intended for very short term use, so I didn't bother to do it right. My own fault.

Peter_V · March 2011

Re: Using different types of wire in a system

mike90045 wrote: »

Aluminum wire has come a long way since the house fires in the 70's, new alloys, better connectors and conductive goop. Understanding the problem was half the battle!

For 3,000 feet of #6, it saved me thousands, now I'm getting ready to order 800' of #4, and 3,000 of #8. Big price difference when you have some long runs.

And copper is not without flaws either. 50 year old #10 wire oxidizes all the way through, and goes rotten. Aluminum only gets oxide on the outer layer, thus the conductive goop with sharp micro bits of something conductive to punch through the oxide.

Totally agree that with long runs aluminum can be significantly cheaper.

However, if Eric has a long run of wire between his charge controller and his batteries, I'm thinking he has bigger problems than the cost of copper.

Perhaps I'm wrong, but I'd think you'd want to keep that loop down to 10 feet or less

waynefromnscanada · March 2011

Re: Using different types of wire in a system

Peter_V wrote: »

Perhaps I'm wrong, but I'd think you'd want to keep that loop down to 10 feet or less

In the ideal world, definitely yes, the shorter any cables can be, the better. Unfortunately most of us don't live there. My PV panels, controllers and inverters, all located in/on the same shed still have a one way run of at least 50 feet between panels and controller. My micro micro hydro is about 400 feet away from the controller, and my cousin, at his cabin in the back woods, has to have a run close to 300 feet one way from his PV to controller, almost 600 ft return. In all cases, especially his, we wire the panels/alternator for a higher voltage to reduce wire losses, and let a MPPT controller look after voltage down-conversion at the batteries. Works well. The alternative in his case, would be no system at all, and in my case, would eliminate the hydro, and require reinforcing an upper storage area to support almost half a ton, and hump heavy batteries up to a second story scaffold. Nope, ain't gonna happen. Gotta work with what we have. BTW, my hydro, producing more or less 140 watts, 24/7, has transmission losses, including controller losses, of about 5 watts. The alternator is putting out about 145 watts, and 140 watts arrive at the batteries. Makes me VERY happy, and yes, the long run from hydro uses aluminum cable.

Peter_V · March 2011

Re: Using different types of wire in a system

waynefromnscanada wrote: »

In the ideal world, definitely yes, the shorter any cables can be, the better. Unfortunately most of us don't live there. My PV panels, controllers and inverters, all located in/on the same shed still have a one way run of at least 50 feet between panels and controller. My micro micro hydro is about 400 feet away from the controller, and my cousin, at his cabin in the back woods, has to have a run close to 300 feet one way from his PV to controller, almost 600 ft return.

Yes, but how long are the wires from your charge controller to your batteries?
That is what Eric was asking about.

System2 · April 2011

Re: Using different types of wire in a system

Peter_V wrote: »

There are a lot of potential problems with using aluminum wire and some of them don't pop up for several years. A lot of house fires were started because of aluminum wires that weren't correctly installed, or in some case WERE correctly installed

Is it really worth the hassle to save a couple dollars? Considering how much you've spent on the rest of the system?

Aluminum wire is just as safe as copper, especially with the new alloys and connectors. Remember, the housing issues were 40 years ago, and the problems were all related to equipment problems that have been corrected and poor installation practices, and usually both together. Look at your connections now, nearly all are made of aluminum in your panels.

Photowhit · April 2011

Re: Using different types of wire in a system

Chris wrote: »

... Look at your connections now, nearly all are made of aluminum in your panels.

I think your seeing what's called tinned copper, copper wire with lead soder, I know MC4 connectors are tinned copper, specs for the tabbing and connecting in a panels are something like this;

Bus wire Basics of Solar Cell:

GAUGE: 0,15200MM
WIDTH: 5,0000MM
US SIZE: 0.006" X 0.1969"
MATERIAL: 96.5SN/3.5AG HOT DIPPED COPPER
SOLDER COATING THICKNESS: 410-600 MICROINCHES/SIDE

The soder protects the copper from oxidation.

nsaspook · April 2011

Re: Using different types of wire in a system

Chris wrote: »

Aluminum wire is just as safe as copper, especially with the new alloys and connectors. Remember, the housing issues were 40 years ago, and the problems were all related to equipment problems that have been corrected and poor installation practices, and usually both together. Look at your connections now, nearly all are made of aluminum in your panels.

Even with the correct connectors and anti-ox AL wiring is a hazard IMHO unless it's cold welded with a special crimp.

Never in my house and not 1 inch in anything I build.

Using different types of wire in a system

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