> Yes and power negotiation does not protect against improper voltage whatsoever.

Oh? Everyone else seems to think the mechanisms are sufficient for safety.

> This wasn't my point, despite me addressing negotiation in another comment.

I still don't understand your point, unless it's a failed effort at pedantry.

If I put 120 volts through to my MacBook directly over the cable it will invariably damage it. Voltage negotiation doesn't matter here.

Also the original comment was unclear; they've edited to clarify. But of course, I'm the bad guy on HN for not being able to read minds.

E: I realize my GP comment was also unclear. I should have said "excessive" voltage, not improper I suppose. "Improper" in my head meant outside the rated voltage for either end/the cable. I'm not the one being a pedant here.

Voltage negotiation matters, because that what keeps a charger from putting 120 volts into your MacBook.

Which is exactly what GP was saying in the very part that you quoted:

> chargers and cables are advertised with the wattage they support, but it's really the voltage and current that matters.

and what you agreed with in that very same comment:

> Also, it arguably does have everything to do with volts

What do you think USB power negotiation is for if not negotiating a mutually supported voltage? That’s pretty much why it exists.

USB-C power negotiation absolutely protects against improper voltage, assuming it is implemented correctly.

Out of curuosity: is there any instance where it isn't implemented correctly that actually damaged/fried some electronics? What I've seen is that in the worst case it doesn't charge or negotiates at a very low voltage and charges slowly.

Yes, I don’t have a search term handy, but there’s someone who maintains a website cataloging these.