[dreamcompiler]

Which implies that Tesla is either using a much higher voltage than 250, or they're using superconductors. And I doubt they're using superconductors.

[DannyBee]

Yes. Residential/basic commercial wiring is the limit of my knowledge here, so i don't know what sort of voltage service they are buying here.

Staring at things like http://bpu.org/electric-service-rates-commercial/

(and similar pages on other utilities)

make me believe they'd end up with some medium voltage application here (IE take it in as somewhere between 3.3kv and 45kv and do step down themselves)

[HALtheWise]

The Tesla supercharging cables are pretty short, so they can also tolerate the higher losses associated with a thinner cable. They were even experimenting with a liquid cooled cable at one point in order to get thinner conductors and a more flexible cable by allowing to to be less efficient.

[Reason077]

The experiment must have been a success, because the v3 supercharger uses liquid-cooled cables.

In fact, it is becoming standard in high-power chargers, with the new 175-350kW CCS units also using liquid cooling.

[URSpider94]

They are using 480V, and their cables are liquid-cooled.

[dreamcompiler]

Ha! I started to suggest "or they're using small copper and cooling the heck out of it," but that would waste energy so I assumed they wouldn't do it. Wrong, apparently.