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Safety Ground Q

I never really understood grounding until I watched the ASR video, assuming the information is correct, of course. Amir says the safety ground does absolutely nothing unless there is a fault in which the case becomes electrified and the safety ground would kick in. I think I got that right, but maybe not.  OK, so if the safety ground is doing nothing, why can lifting it eliminate a ground hum?  It seems the safety ground would have to be doing something other than waiting for a short if eliminating it reduces hum. Thanks. 

chayro
erik_squires
15,755 posts
 

This article may help.  Apparently ground pins started appearing in 1967.  For some reason people still think of Neutral and Ground as equivalent but don't ask, if they are the same thing why are they on separate pins and conductors?

 

https://www.howtolookatahouse.com/Blog/Entries/2018/7/when-were-grounded-three-slot-receptacle-outlets-first-required.html

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cleeds
5,654 posts
 
erik_squires

For some reason people still think of Neutral and Ground as equivalent but don't ask, if they are the same thing why are they on separate pins and conductors?

If nothing else, they are tied together at the service panel.

carlsbad2's avatar
carlsbad2
1,378 posts
 

Good discussion.  

I'll add something that is somewhat obvious but some may not understand it:  Neutral and ground, being tied together at the panel, will both "work" to run a piece of equipment.  So if something is wired wrong, there may be no indication until something shorts.   Also you might get a bit of a tingle touching the frame which would indicate a problem.

And in Audio Equipment, you can get a noisy ground loop. 

Jerry

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