Sine Wave Inverter Anomaly

If your trailer is wired to code, ground and neutral CANNOT be bonded together anywhere in the trailer when it is plugged into shore power. Code only allows bonding at the main distribution panel for the power. That is (a) the breaker panel in your house (b) the breaker panel at the campground etc.

Check your trailer with an ohmmeter. if it is wired to code you will find 'infinite" resistance between the neutral and ground if you check at the main plug.

Gdetrailer wrote:
This is correct.

The breaker panel in your RV MUST have no "connection" or "bond" between "neutral" (white) and "equipment ground" (green or bare wire) WHEN CONNECTED TO COMMERCIAL SHORE POWER.

The RV breaker panel acts like a "SUB PANEL" to the MAIN HOME OR SHORE PANEL and as a sub panel it must have neutral and equipment grounds on separate buss connections.

It has to do with making sure there is no current flow on the EQUIPMENT GROUND at all times when connected to commercial shore power.

The problem starts however once you disconnect from commercial power and your inverter or generator now becomes your power source.

Once you are "mobile" you now have NO EARTH GROUND to work with and the equipment ground now has the potential to have a voltage ABOVE ground.

Your neutral AND HOT have no reference to earth ground and hence they BOTH are above ground. In a sense the system is now a "two wire" electrical system or "floating" system.

EMS systems tend to not deal with this very well and will typically shut off the power to prevent a possible hazard.

You do run some danger however with this setup since it is possible to have "leakage" currents get referenced to the earth ground via stabilizers and jacks through the RV frame.. A good rain will enhance the the electrical connection through the jacks which could give you a buzz.

Since the above explanation clearly makes sense I decided I should check my own trailer ... after all, it's a 2014 wearing the usual stickers confirming it meets all US and Canadian standards, so it should be wired as described above. With my DVM set to read resistance it showed no connection whatsoever between the main service ground and neutral ... I measured right at the male 30 amp plug and if I found any conductance at all planned to then back track through the system right to the converter, eliminating the cable, Surge Guard, etc along the way to find the source of this bonding. That wasn't necessary as my DVM indicated no signs of bonding whatsoever between ground and neutral even with all these components still in the path ... which therefore takes us back to my original question - the polarity checker shows an erroneous "open ground" error which we know is triggered by a floating neutral when it alone is plugged into either my 1000 watt sine wave inverter OR my EU2000i genset but the question is WHY does that co-called "error" immediately disappear as soon as I plug in the trailer's main service cable even though it, according to my DVM, is not bonding neutral to ground? :h