New EMS shows Open Ground ?

CA Traveler wrote:

Harvard wrote:
I just realized this RV is a trailer and not a motorhome. It matters because any trailer jacks that touch earth ground are going to provide a parallel ground path to the wired GREEN ground wire. Safety wise this is NOT an issue BUT it may be interfering with the trouble shooting voltage readings IF the GREEN GROUND wire is OPEN and not grounding the trailer

I would disagree. ANY GROUND FAULT exceeding the standard safe limit of 5 ma is a safety issue waiting for a opportunity. The potential for animal or human significant shock should always be considered a issue IMHO.

Just to clarify the not so obvious:

The danger here is IF the GREEN GROUND WIRE to the service is NOT INTACT, the secondary (or parallel) paths to EARTH through jacks MAY mask (hide) the "Open Ground" defect making it appear all is normal. When in fact, the electrical return path through earth will not conduct current sufficent to blow a standard breaker (Not with standing if it is a GFCI breaker).