Literature from one manufacturer claims that their unit, which is 7Kw single-phase, provides open pen protection in accordance with 722.411.4.1 (iii) but does not require an earth electrode. If the claim is correct, am I missing something? For compliance with that indent, I thought that the only way it could be done was to provide a measurement electrode unless the unit was three phase.
My guess would be that it measures the LE voltage and the NE voltage. LE should be about 230V and NE should be about 0V. Anything else suggests a fault - and it doesn't really matter exactly what the fault is. A completely broken PEN is liable to float at about 115V, especially if there are LE and NE filter capacitors.
My guess would be that it measures the LE voltage and the NE voltage. LE should be about 230V and NE should be about 0V. Anything else suggests a fault - and it doesn't really matter exactly what the fault is. A completely broken PEN is liable to float at about 115V, especially if there are LE and NE filter capacitors.
