Re:Why we ground electrical systems (2015)
by jhayward on Friday August 02, 2019 @03:27PM
(#20595838)
If the EGC is floating, it's not an EGC. EGC is tied back to Neutral at the distribution point. Its sole purpose is to carry fault current.
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And the neutral is tied to (earth) ground. Otherwise all metal devices would shock you if you touched something earth referenced, such as a radiator, at the same time.
Edit to clarify: In principle, only the voltage difference between Live and Neutral matters for running a device. So theoretically one could construct a building supply where Neutral is not at earth potential. However, EGC has to be at earth potential, otherwise there would be a voltage between any metal electronic device and earthed objects, such as radiators or your feet standing in a puddle. This means that in practice both Neutral and EGC are always physically connected to the earth in some way and have to be for the system to work properly.