... if the safety ground is doing nothing, why can lifting it eliminate a ground hum?
Because in an unbalanced system, it's usually tied to the neutral. Hence, two paths to ground.
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.
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@cleeds I think you are mixing up 1980’s appliance manufacturing with audio gear. I can’t think of any piece of audio gear manufactured in the last 50 years which would do this, balanced or unbalanced. It would violate several codes and set you up for some really nasty noise and safety problems if this was true. |
I think @cleeds brings up a good point by accident. The reason ground loops in audio gear happens is probably due to historical oversight. Stereo appliances went from being all in one units without grounds to separates with a separate chassis ground and, at least for unbalanced signals (using RCA) , never quite reconciled the difference between a signal ground and safety ground. |
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