USB port shield is a known good ground on devices with a USB port.
Oh ya, that too I've been messing w/ this old effing WRT54GL too much the past couple days. :-/ Actually, the LAN ports' housing is likely grounded* too.
* In this case, referring to the reference in a circuit board...
mwchang wrote:
I never know how you got a ground when the AC plug had only 2 pins (e.g. in USA)...
Easy, cuz if a ground is needed, polarized plugs are used, and electrical code requires the neutral (reference) line to be connected to ground (which literally goes to an earth ground - rod in the dirt) at the electrical box. Of course, this may not always be the case, esp. in older homes.
Devices that are 2-pin unpolarized means they use a transformer (like our power supplies) and have no exposed conductive surfaces (like e.g. a toaster). So to be fair, yes the voltage is with respect to the 'reference/negative' which is not really 'ground'. Way easier to say 'ground' though. Now we've thoroughly beaten this dead horse.
Project of the day: take a multimeter and test the voltage from a transformer 'negative' and stick the other lead into the dirt. _________________ #NAT/SFE/CTF: limited speed w/ DD#Repeater issues#DD-WRT info: FAQ, Builds, Types, Modes, Changes, Demo#
OPNsense x64 5050e ITX|DD: DIR-810L, 2*EA6900@1GHz, R6300v1, RT-N66U@663, WNDR4000@533, E1500@353,
WRT54G{Lv1.1,Sv6}@250|FreshTomato: F7D8302@532|OpenWRT: F9K1119v1, RT-ACRH13, R6220, WNDR3700v4
Last edited by jwh7 on Wed Sep 22, 2021 23:44; edited 1 time in total
Joined: 08 May 2018 Posts: 14244 Location: Texas, USA
Posted: Wed Sep 22, 2021 18:25 Post subject:
The only cases I know of that are "different" are industrial / commercial / (even) residential 3-phase grounded or un-grounded distribution systems. I will tell ya that getting tickled by 480v 3-phase doesn't feel good. I still get random cramps in my right hand. That moment when you realize that a tag-out guide list is slightly incorrect Of course, guess who had to review and fix all of these discrepancies, even though I had nothing to do with developing them I see your dead horse and raise you glue! _________________ "Life is but a fleeting moment, a vapor that vanishes quickly; All is vanity"
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