Sine Wave Inverter Anomaly
After following this recent discussion about how to best utilize a sine wave inverter for RV use I decided to go ahead and buy the 1000 watt model mentioned in this discussion since it was on sale for...
Forum Discussion
ktmrfs wrote:brulaz wrote:
Ok. As you suggest, I'll stick with my trusty multi-meter to check for bonding.
Now if I understand this correctly, your inverter's 120V output becomes bonded only when plugged into the RV. So I guess there's a connection between ground and neutral somewhere in the 120V distribution panel, or ... somewhere?
Not sure if Prog Ind would think that's a good idea (see quotes above).
Also this bonding doesn't seem to blow up the inverter (a good thing!) which implies that the inverter is not as cheap as it could be.
Think I'll email Prog Ind with a query about all this.
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.
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.
