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The 500k-ton typo: Why data center copper math doesn't add up

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Re: The 500k-ton typo: Why data center copper math doesn't add up

#101

Post by bradfa »

sidewndr46 wrote: post #87
bradfa wrote: post #79

With a higher voltage you can reduce your copper needs by a substantial amount. Seems if copper cost was a concern this would be what these data centers would do.

Agreed. I was kind of surprised to see 54 VDC mentioned. I am assuming this is low enough to meet some threshold for some kind of safety regulation. In other words, it doesn't shock you just 220 VAC would. I'm not entirely convinced of that however as it turns out bus bars are really dangerous in general. A 54 VDC bus bar won't shock you, but if you drop even a paperclip between the bus bar and a metal part that is g…

My experience has been that SELV (safety extra low voltage, less than 60V peak and less than 240VA) is considered safe and anything exceeding that needs certain levels of protection.

But bus bars generally should be protected regardless of voltage as they carry currents from high current capacity sources so even a lower voltage can be a safety concern.

Many server power supplies can take AC or DC input, with the DC input in the 300-500V range as this is comparable to the boost voltage for the AC power factor correction circuit. I just assumed most data centers using DC would be distributing around 400V within each rack.

Re: The 500k-ton typo: Why data center copper math doesn't add up

#102

Post by carlesonielfa »

Fiveplus wrote: post #30

The funniest part is beyond the typo, the complete lack of physical intuition from the analysts who circulated this. 500,000 tons is roughly the weight of 1.5 Empire State buildings. If your rack busbars weigh more than the structural steel of the facility housing them, you have a geotechnical engineering crisis on your hands. It is wild that we reached a point where financial modeling is so decoupled from physical r…

My first thought was, this is the kind of thing that an LLM writes and nobody checks. But then I realized, any decent LLM would have probably caught that inconsistency

Re: The 500k-ton typo: Why data center copper math doesn't add up

#103

Post by quesera »

margalabargala wrote: post #92
MSFT_Edging wrote: post #44

Earlier quoted context omitted.

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.

Household 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.

Only 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.

Re: The 500k-ton typo: Why data center copper math doesn't add up

#104

Post by Nifty3929 »

coldcode wrote: post #55
eterm wrote: post #5

Earlier quoted context omitted.

If only there were some kind of international system of standard units.

I thought all measurements in data centers were in US football fields.

For the floor area or length/width it is, but if you want the height then that's in Empire State Buildings.

Re: The 500k-ton typo: Why data center copper math doesn't add up

#105

Post by nerdralph »

crote wrote: post #27

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, whic…

Most residential 200A electrical panels use tin plated aluminum busbars. https://www.eaton.com/cr/en-us/catalog/power-connections/bus...

Re: The 500k-ton typo: Why data center copper math doesn't add up

#106

Post by SoftTalker »

matthewaveryusa wrote: post #84
Fiveplus wrote: post #30

The funniest part is beyond the typo, the complete lack of physical intuition from the analysts who circulated this. 500,000 tons is roughly the weight of 1.5 Empire State buildings. If your rack busbars weigh more than the structural steel of the facility housing them, you have a geotechnical engineering crisis on your hands. It is wild that we reached a point where financial modeling is so decoupled from physical r…

Just to make it even more real: During covid I added a sub-panel and the wire (more like the sausage given the girth) between the sub-panel and main panel was aluminum because of cost. You just need to be a tad careful at the connection points with copper -- nothing a caring literate person can't handle

The incoming drop for a service panel is almost always aluminum (at least the residential stuff I've seen). It's cheaper and lighter than copper while still being ductile enough to work with. Just use the proper antioxidation paste at the connection point.

Re: The 500k-ton typo: Why data center copper math doesn't add up

#107

Post by viggity »

Fiveplus wrote: post #30

The funniest part is beyond the typo, the complete lack of physical intuition from the analysts who circulated this. 500,000 tons is roughly the weight of 1.5 Empire State buildings. If your rack busbars weigh more than the structural steel of the facility housing them, you have a geotechnical engineering crisis on your hands. It is wild that we reached a point where financial modeling is so decoupled from physical r…

Kinda like when someone said that instead of running for mayor, Bloomberg could have given everyone in the country $1M. A guest said it on NBC and Bryan Williams, nor the pundit had any intuition that it seemed grossly wrong. https://www.politifact.com/factchecks/2020/mar/06/msnbc/bad-...

Re: The 500k-ton typo: Why data center copper math doesn't add up

#109

Post by pfdietz »

crote wrote: post #60
candiddevmike wrote: post #35

Earlier quoted context omitted.

AFAIK Aluminum wires will become a heat liability, especially at higher amps

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.

Aluminum has lower resistance per kg, or per $. This is why transmission lines use aluminum (around a steel core).

Re: The 500k-ton typo: Why data center copper math doesn't add up

#110

Post by amluto »

crote wrote: post #27

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, whic…

> 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.)

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