ground neutral tester

[gink]

I recently acquired an Instrutek GN-3 ground neutral tester. It
appears to work, but I don't know what its operating principle is.
Inside is a pc board, about 3 inches square, with one ic and various
components. An analogue meter on the front, with a reference adjust
pot, a ground or neutral select toggle and a push button. It doesn't
use probes, apparently getting all information from its power plug.

Does anyone know how it operates? Any information gratefully received.
Instrutek did not reply.

thanks, gink

 

[Charles Schuler]

The neutral is at ground potential but normally carries current. The ground
only carries current in the case of a fault. Perhaps it senses the voltage
difference between the two or the impedance difference?

 

[Charles Schuler]

it measures the current in the live and neutral and trips if they are not
equal and opposite.

fault currents that don't flow in the protective ground conductor are much
more dangerous than those that do.

That's a ground fault circuit interrupter (GFCI). You could be right in
that that was what the OP was describing.