EARTH FAULTS are an especially complex problem & the general belief is that the Earth Faults of 440V or on the high voltage system are important. The secondary voltage, generally 220V or 110V are not considered important since there is already a transformer in place that provides 'galvanic isolation'. Go back and read that! If you got all that then here's the reason we should especially worry about the earthfaults on the domestic voltage level. Would it surprise you to learn that the earth faults left unattended could even cause fire. It could also knock off the power to control equipment & the equipment being controlled could be critical. Back in the office we were looking at an instance where a ship's whole accommodation section was scorched. The attributed reason was incendive sparks, faulty equipment & incorrect wiring terminations. However, the possible earth fault that may have triggered the event seemed to be low on everyone's agenda. Lesson's learnt: Fire on board is still the most serious contingency there is. It does not happen too often; but when it does, it's the crew's readiness to act & system implementation inculcated to grueling routines over the years,that save the day. Trust your instincts'; Have faith in reason. Train through the year to be able to tell which situation you are in. Today, this is called, "Situational Awareness'.