Hacker News Reader

Comment by boltzmann-brain | Hacker News Reader

That's not true, a lot of the connectors just-so-happen to be rated for mains levels. This is because often USB chargers aren't ground referenced, so they hover at a little above 1/2 mains voltage. This is why if you touch some chargers or devices that are charging you get this weird electrical "sensation" sometimes.

View on HN

They are galvanically isolated. If you're getting any sensation at all, something is clearly wrong.

No, they're not. Two-prong power supplies need to have EMI suppression capacitors which connect the secondary side of the power supply's transformer to mains [1]. The mains voltage is present on the output, but the maximum current is low enough that it is safe. It is considered not an issue by manufacturers [2] and it is a fact of many practical power supply designs. Please have any idea what you're talking about before you throw around technical terms like "galvanically isolated". You're clearly not an EE.

[1] https://electronics.stackexchange.com/questions/478607/feeli...

[2] https://www.dell.com/en-us/blog/notebook-tingle-sensation-wh...

Being connected via 2 caps is considered "galvanically isolated"

If you're feeling "tingling sensation" your protection caps are fucked Mr. EE

Galvanic isolation means "no current is allowed from primary to secondary side". This is true of capacitors... but only in theory. Real life capacitors have leakage resistance and therefore do not, in practice, form full galvanic isolation.

Capacitive coupling still counts as galvanically isolated. Dielectric resistance of typical Y caps is in GOhm range, so that's basically galvanically isolated, unless you're some kind of purist. You certainly will not be able to feel that.

Reactance of a typical Y capcaitor at 50Hz is in the range of single unit MOhm so even that does not cross perception thresholds of most individuals even at 230 V. But it may for some, I guess.

Also what the heck with the first link. Apliances with metal enclosure must be grounded. That guy has no business having 50V against ground on the metal enclosure.

Reply on news.ycombinator.com