Let's fight about aluminum wire!

[cardboardboxprocessor]

The timeless debate whether aluminum is good or bad. Of course old aluminum we all know is bad but newer alloys are supposedly not. The feeder lines in my house and all my main panels for my attached . The feeder lines in my house are aluminum.

Is there any specific reason I should not use aluminum wire of the appropriate gauge (which is bigger than copper And it's cheap enough that I could even go an extra gauge above that to prevent thermal expansion from being too much) for the main run from the solar panels combiner box to the inverter box?

If this is possible are there any extra precautions to take besides the special grease that prevents oxidation. Can I not crimp onto aluminum must it feed directly into the aluminum rated breaker? I see most people crimp on little tabs on the end of copper wire Just curious if it is different for aluminum I have not seen that anywhere.

 

[Hedges]

PG&E crimps to aluminum wire. Maybe after surface preparation and application of corrosion inhibitor.
I've seen it for transformer vault and overhead drop.
Key would be connector listed for the purpose and correct tool.

If not crimp, just get screw terminals/lugs rated for it.

 

[ricardocello]

Them's fightin' words!

With feeder lines, you have to use the anti-oxidizer gray goopy stuff (Noalox) into terminals rated Cu and Al.
I personally use 220 ft of 2 AWG duplex URD Aluminum for the run from my ground mount to the house.
But it terminates into standard terminal blocks. Then regular copper THHN/THWN2 from there to the breakers.

 

[hwy17]

Aluminum is the future. When copper price goes up, it's coming back. The industry is preparing a new line of copper clad.

That said, all my solar equipment terminals say CU only, and all my solar wiring is 10awg or less, which isn't generally available in aluminum right now.

The premise of this question makes me wonder whether someone is running voltage drop calcs on their solar wiring though. Don't do that.

 

[ricardocello]

I would only consider Aluminum useful for 4 AWG or bigger.

Who wants to run 8 AWG aluminum instead of 10 AWG copper? Maybe if copper were 5x the current price. Everyone has their price.

Also, I can't imagine crimping a 6 AWG 5/16" lug onto aluminum, especially if it is made of copper (even tinned).

 

[Brett V]

Aluminum is the future. When copper price goes up, it's coming back. The industry is preparing a new line of copper clad.

copper clad aluminum generally gets a bad rap because it’s often passed off as “copper wire” by less than honest vendors. But if you know what you’re working with and size accordingly, it’s perfectly capable of doing the job.

 

[zanydroid]

copper clad aluminum generally gets a bad rap because it’s often passed off as “copper wire” by less than honest vendors. But if you know what you’re working with and size accordingly, it’s perfectly capable of doing the job.

CCA for comms cable is very different from power cabling, in terms of how the sellers play ball with the ecosystem.

Comms cable is scammy and they don’t kowtow to the Ethernet standards body.

CCA for power cabling is by people that insinuated themselves into the NEC process

 

[seneysolar]

The problem I see be expansion and contraction of the terminated ends. Keeping them tight after numerous heat cycles.

Otherwise aluminum is a good conductor

 

[Tulex]

Wire is a one time buy, it's an investment. The reason people don't mind using aluminum for feeder lines is that it's before the meter. Everything about copper is better except the price. I can't see using aluminum except in industry.

 

[Mattb4]

Aluminum wire or copper wire. Just no copper clad aluminum wire. History has shown why that is a bad idea. Amazing that the idea has came back around after so many electrical fires were caused by CCA.

 

[cardboardboxprocessor]

The premise of this question makes me wonder whether someone is running voltage drop calcs on their solar wiring though. Don't do that.

Hi what do you mean by don't do that? Why not? Didn't worry about voltage drop?

It's not the reason I need thicker cable though. Strictly amps. I never cared about 3% drop.

 

[ricardocello]

Voltage Drop: V= IR
Power Lost: P = I^2 R = V^2/R

I care about power (W) lost in my PV cables as a function of current (I), more than I do voltage drop.
If my panels are generating 1920W, but I’m losing 100W in the run, that is signifcant.
Losing 10W, who cares?

 

[cardboardboxprocessor]

Ah i see what you meant.

 

[hwy17]

Hi what do you mean by don't do that? Why not? Didn't worry about voltage drop?

It's not the reason I need thicker cable though. Strictly amps. I never cared about 3% drop.

You get it then. Voltage drop is real, it can be considered for power losses, but wires should usually be sized for just amps.

 

[Rednecktek]

The other issue with Al wiring, and one of the big reasons it was pulled from the NEC for indoor circuits, is the oxide that forms on the wire acts as an insulator at the terminal screws and next thing you know the outlets catch fire.

I've had it happen a couple times.

 

[Hedges]

My point of view on voltage drop over PV wires is it doesn't impact functionality, unless voltage drops below minimum for MPPT.
And, it is greatest during most productive times, when you're more likely to have surplus.
So it is fair game to trade off against things like cost.
If voltage headroom remains, the loss is easily replaced with more panels in series, and that helps the poor times too.

The other issue with Al wiring, and one of the big reasons it was pulled from the NEC for indoor circuits, is the oxide that forms on the wire acts as an insulator at the terminal screws and next thing you know the outlets catch fire.

I've had it happen a couple times.

Cu/Al rated?

Outlets tend to have more rinky-dink connections. But hopefully that was something like a stove outlet, not 15A ones, with a decent setscrew. (I've bought all sorts of 30A & 50A outlets, however).

Is Al not allowed for indoor circuits anymore? I thought just not for 20A lighting and convenience outlets. But I'm not sure.

 

[cardboardboxprocessor]

The other issue with Al wiring, and one of the big reasons it was pulled from the NEC for indoor circuits, is the oxide that forms on the wire acts as an insulator at the terminal screws and next thing you know the outlets catch fire.

I've had it happen a couple times.

In use no-ox-di on everything mostly. For aluminum I guess I'd have to research it vs noloax

 

[Rednecktek]

Al was common in the late 70's and 80's but was pulled because of fires from lighting and outlet circuits. Any house built before about 1992 is likely to have Al wire in the walls.

Even then, higher amp loads like stoves and dryers tended not to get the bump up in wire size from copper and were known to have issues after a decade or two, especially in humid climates like the PNW and New England.

It was a Make It / Break It for me buying a house, no way with Al wiring.

 

[zanydroid]

Branch circuits with aluminum, going into regular screw terminations etc, kind of sketch me out (and it’s tough to sort through the CCA noise).

Feeders going into breaker and panel lugs, I have no problem with because you can expect to take your time with them, there being so few. My AHJ enforces torquing of feeder terminations.

I have one 50A Al branch circuit in my house, going to my kitchen. Kind of sketchy but it is adapted to copper via Polaris connectors now which is similar to the quality level it would be done to for a feeder.

 

[B-Mod]

You guys are babies. AL wire is just fine if you know how to install it. Most AL wire today does not even need a de ox added. I still do it, but it is not required.