Sanity Check - RCD Trips with Safe Isolation

[sparkticus]

Less than 5 volts because the voltage is the difference between the potential on the neutral bar and the potential on the neutral block in the cut out where the CPC is jointed the the neutral. This is a very short and very low impedence length of circuit, typically less than 0.1 ohms, so with 50 amps flowing through it the potential developed between those points is typically less than 5 volts ( 50 A x 0.1 ohms ).

Ah I see, you meant specifically a TN-C-S system? Yes I would agree with that.

thank you

 

[bernardgreen]

Ah I see, you meant specifically a TN-C-S system?

Yes I did, TT supplies are different in that the voltage between neutral and CPC depends on the quality of the local area network. The incoming neutral may not be at true ground potential due to un-balanced phase loading while the CPC will be at the potential of the ground where the earth rod is located.