If by “special” you mean ordinary low-cost lugs, then sure.

Check it out:

https://lugsdirect.com/WhyAluminumOverCopperFAQ.htm

And you can browse that site for lugs, and they’re mostly rated for aluminum and copper. Copper-only lugs are actually rather unusual.

Sure, you can’t stick copper and aluminum wires into a wire nut, and finding terminations for smaller-gauge aluminum wire can be hard. But for larger wire, it’s really no problem.

Most wiring device terminations and lugs are Al/Cu rated. You’re supposed to use specific fittings for splicing together aluminum and copper wire (specific WAGO lever nuts are UL listed for this purpose along with some others), I assume that’s what you meant.

That's the "a pain to work with" part.

Residential aluminum is a Really Bad Idea because DIY Dave will inevitably do something wrong - which then leads to a fire hazard. Copper is a lot more forgiving.

But a large scale datacenter, solar farm, or battery storage installation? Those will be installed and maintained by trained electricians, which means they actually know what a "torque wrench" is, and how to deal with scary words like "corrosion" and "oxidation".

Like I said: it's what's used for most of the power grid. With the right training it really isn't a big deal.

Aluminum got a bad rep due to a lot of poor installations made in the 1960 and 70'ies. Subsequently new alloys (AA-8000 series) for wiring, new installation and termination procedures etc. have been developed, and AFAIU the situation today is much better. It's still trickier than copper wiring, so probably not a good option for DIY, but for some industrial installation with competent personnel and where the savings can be substantial it could certainly be an attractive option.

https://en.wikipedia.org/wiki/Aluminum_building_wiring

Aluminum oxide has high resistance and if you mix aluminum wiring with copper outlets, etc the impedance mismatched is what causes fires. You need to either have special copper pigtails installed or use fixtures that are rated for aluminum wiring.

For commercial installs, it shouldn't be a problem as long as it's planned for.

It's because aluminium has a higher coefficient of thermal expansion. It expands and shrinks more as it heats, and as those cycles add up it tends to loosen electrical connections. Loose connections have higher resistance, heat up and can cause fires.

That said, there is no reason we can't design better connectors that can withstand the expansion and shrinkage cycles, like spring loaded or spring cage connectors.

Old aluminum wiring in your walls with cloth insulators, designed for a time where electricity consumption was a small fraction of today's electrified usage is dangerous because you're overloading an old, unprepared system.

Aluminum bus bars(solid, often exposed) would be designed for the required power levels and installation criteria.

Unless I'm mistaken, the risk with aluminum is that it can expand and contract if it gets too hot. Aluminum sized properly with the correct connectors torqued to spec would be fine, aluminum wires in a residence with a DIYer working on it can be riskier and is why inspectors will always note it.

Aluminum wires became brittle over time(tens of years), fluid which requires some maintenance for screw terminals and inducts galvanic corrosion when coupled with copper without special care. If wiring was properly done and maintained, it is okayish.

Old aluminum is dangerous. Modern aa-8000 series aluminum is fine. Bigger pipes though.

If you apply antioxidant paste, torque the terminations to the correct value, and use wiring devices rated for Cu and Al conductors, there are zero problems.

Most homeowners know none of the requirements of aluminum wire installation so I don’t recommend using it, oxidation is bad and can cause fires. Just pay for copper NM cable, it’s dirt cheap anyways.

FWIW I sell and run electrical work for a living. I assume crote and amluto work in the electrical industry, since they’re the only other posters in this discussion who know what they’re talking about.

It’s a fire hazard in residential houses where people frequently do their own wiring, because it needs more expertise to wire correctly. Copper wiring is a lot more forgiving to being hooked up by amateurs.

The biggest reason is that aluminum oxidizes, and unlike copper, the oxide layer has high resistivity. In theory that shouldn’t be an issue in datacenters hiring expert technicians.

It used to be extremely expensive!

The Washington Monument has an aluminum cap, which at the time was as expensive as silver. Two years later the Hall-Héroult process was invented, and as a result the price plummeted.

Aluminium essentially reflects electricity prices and increasingly recycled

That's why my calculation example used a 1.5mm2 copper wire but a 2.4mm2 aluminum one.

Aluminum has a higher resistance, which means the same diameter will get hotter than copper. Make the cable thicker and its resistance drops, which means it gets less hot.

Want more amps at the same temperature? Ohm's law still applies: just use a thicker cable.

Any wire---of any non superconducting material---will be hotter at higher current flows. You size the wire to the application.

It depends on design, environment and maintenance. If it's well protected against oxidation and it's static, it's not really a problem. Heat issues are often at the joints, which are most vulnerable, but can be coated and encapsulated to mitigate. For some uses, aluminium is superior to copper all things considered. Obviously the diameter of the wire/cable depends on which conductor you use, AC/DC, current and service temp - for some applications, that may favour one material over the other.

If the two wires are the same gauge, yes. If you size up the aluminum, at the same resistance/current would mean the same amount of power over the length of the conductor and same heat.

Thicker cables or higher voltage(lower current) is the answer which is why it's used in power distribution networks where they can control the voltage by planning what to transform to.

> and cheap enough

Not anymore. :(

I would imagine most large-scale data center construction projects will include electrical engineers to design the electrical subsystem. A rack's floor footprint is a few square feet. You can put several million dollars of hardware into that rack. A data center will have at least a few racks. It's a very reasonable investment to bring someone in to do electrical design.

This isn't true at all unless you narrowly dwfine "the entire system".

Each feeder can be aluminum if you put special goop on any copper connections. Breakers accept it just fine, etc.

You should avoid it for smaller wiring, though. There's special 8000 series aluminum if you're trying to be serious with Al feeders