6 ms·
With regards to the copper market: it keeps surprising me that some people seem to assume copper is a hard requirement for conducting electricity. In reality c
by crote 10mo ago
With regards to the copper market: it keeps surprising me that some people seem to assume copper is a hard requirement for conducting electricity.
In reality copper is just convenient. We use it because it's easy to work with, a great conductor, and (until recently) quite affordable. But for most applications there's no reason we couldn't use something else!
For example, a 1.5mm2 copper conductor is 0.0134kg/m, which at current prices is $0.17 / meter. A 2.4mm2 aluminum conductor has the same resistance, weighs 0.0065kg/m, which at current prices is $0.0195 / meter!
Sure, aluminum is a pain to work with, but with a price premium like that there's a massive incentive to find a way to make it work.
Copper can't get too expensive simply due to power demands because people will just switch to aluminum. The power grid itself had been using it for decades, after all - some internal datacenter busbars should be doable as well.
- fedeb95 10mo agointeresting, thanks!
- candiddevmike 10mo agoAFAIK Aluminum wires will become a heat liability, especially at higher amps
- lillecarl 10mo agoThicker 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.
- greggyb 10mo agoAny wire---of any non superconducting material---will be hotter at higher current flows. You size the wire to the application.
- MSFT_Edging 10mo agoIf 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.
- crote 10mo agoThat'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.
- pfdietz 10mo agoAluminum has lower resistance per kg, or per $. This is why transmission lines use aluminum (around a steel core).
- mmulqueen 10mo agoIt 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.
- quickthrowman 10mo agoYou are incorrect. Wire can be used for up to whatever ampacity is listed for that size wire and temperature rating in Table 310.16 (Conductor Ampacity) Copper and aluminum have separate ampacity tables because you need to use larger aluminum conductors. Example: #250MCM THHN copper can handle 255A in a commercial setting (75C column) #250MCM THHN aluminum can handle 205A in a commercial setting (75C column). NEC ampacity table: https://media.distributordatasolutions.com/ThomasAndBetts/v2/part2/files/File_7437_emAlbumalbumsOcal20(USA)oc_1_g_nec31016pdfClickHerea.pdf https://media.distributordatasolutions.com/ThomasAndBetts/v2...
- dzink 10mo agoYou just have to not mix and match. If you mix them the two need special bonding at every single connector or they can cause arching and fires.
- amluto 10mo agoIf by “special” you mean ordinary low-cost lugs, then sure. Check it out: https://lugsdirect.com/WhyAluminumOverCopperFAQ.htm 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.
- quickthrowman 10mo agoMost 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.
- y-curious 10mo agoI am not an electricity/wiring guy so maybe you can help me understand. I thought aluminum is dangerous to wire with because it is a fire hazard (I bought a home this year and this was a prominent warning in my reading). Is that because it needs to be done very carefully? I imagine most data centers would not mess with a fire risk on such a scale.
- deleted 10mo ago[deleted]
- MSFT_Edging 10mo agoOld 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.
- Aurornis 10mo agoAluminum home wiring was from the 60s and 70s. It’s not the same as cloth covered knob and tube from earlier years. It has its own problems, but I’d take a house with knob and tube over a house with aluminum wiring.
- margalabargala 10mo agoHousehold electrical usage has decreased, not increased, since that time. Your scaling is backwards. Old aluminum wires in your walls were designed for a time when you lit your home with 100 watt incandescent lamps rather than 12 watt LEDs.
- quesera 10mo agoOnly true for lighting circuits though, and most household circuits are mixed. The quantity and (edit: aggregate) power draw of modern appliances is far greater now than 60 years ago, so the overall load on the old wires is much higher.
- kmbfjr 10mo agoAluminum conductors are dangerous unless the entire system is designed for it. It is not a case of switching to something cheaper. Look at the electrical fires of the 1950’s and 1960’s as an example, and that was at household levels of current. Aluminum is used, but everything accounts for the insane coefficient of linear expansion and other annoying properties.
- greggyb 10mo agoI 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.
- knollimar 10mo agoThis 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
- amluto 10mo agoThe goop is generally considered to be unnecessary. What you need is a termination that is rated for aluminum wire, and these are very, very common as long as the wire in question is fairly large (8AWG or so and larger).
- knollimar 10mo agoI only put it in the comment since the commenters here seemed uninformed. It's better to be safe and follow specs; it's more when you're doing some compound splice where it makes sense. I figure it'll make more people feel easy about it if there's a preventative measure
- nirui 10mo ago> In reality copper is just convenient. We use it because it's easy to work with, a great conductor, and (until recently) quite affordable It's convenient, it's easy to work with, great conductivity, and cheap enough all at the sametime... Dude, I think you just explained why cropper is used instead of anything else.
- jandrese 10mo ago> and cheap enough Not anymore. :(
- quickthrowman 10mo agoWire has barely gone up in price, I was paying $175 for 1000’ of #12 THHN a year ago and today it’s about $190 for 1000’ of #12 THHN. It’d be nice to get 1000’ of 12-2 MC cable for $500 again, but those days are gone.
- zahlman 10mo ago> In the Earth's crust, aluminium is the most abundant metallic element (8.23% by mass[68]) and the third most abundant of all elements (after oxygen and silicon). TIL. I thought it would be relatively expensive due to the difficulty of extracting it. (Iron is much cheaper than I thought, too.)
- crote 10mo agoIt 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.
- newyankee 10mo agoAluminium essentially reflects electricity prices and increasingly recycled
- nerdralph 10mo agoMost residential 200A electrical panels use tin plated aluminum busbars. https://www.eaton.com/cr/en-us/catalog/power-connections/busbars.html https://www.eaton.com/cr/en-us/catalog/power-connections/bus...
- quickthrowman 10mo agoMost commercial panelboards and transformers also use aluminum buss.
- amluto 10mo ago> Sure, aluminum is a pain to work with Really? In larger sizes, an equivalent ampacity aluminum cable is generally lighter and more flexible than copper. The main downside is that it’s thicker. (Common terminations for larger wire sizes are often dual-rated for aluminum and copper. The engineering details for how to design lugs that work well for aluminum and copper were worked out long ago.)
- pfdietz 10mo agoOne good reason for moving from copper to aluminum is that copper contaminates recycled steel, but aluminum doesn't. Fortunately these days it's profitable to carefully extract most of the copper wire and such from scrap steel before it's melted down.