protective devices either, as I2, limited by the ground resistance RG2,
might be too low for their instantaneous pick up.
As a result, the ground fault can permanently energize pole B and
cause stray voltage over it.
Alternatively, earthing the lighting poles collectively would allow
overcurrent devices to trip, in the case of double faults (Fig. 15.12).
The fault current, in fact, corresponds to a short circuit phaseneutral, and the overcurrent device can promptly disconnect the supply. Electrical safety is, thus, assured, even if the RCD may still not
intervene due to its desensitization caused by the neutral-to-enclosure
fault.