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Comment by londons_explore

1 day ago

> Glass insulated cable sounds like a tech that should be prototyped on smaller scale

Take a close look at an incandescent light bulb... There is an inch of glass insulated cable there...

Yes, but it's just an inch - and we need a continuous extruded wire at least a dozen meters long. Even on the scale of an inch, thermal expansion coefficient mismatch problems exist - this was a notorious issue with manufacturability of early vacuum tubes.

Turns out it's rather tricky to make glass bond to metal well enough.

The glass in a lamp is not for electrical isolation, it's intended to prevent the cable from literally burning up by keeping oxygen out and protective gas in.