Neutral-ground bonding II

[Ray D]

Okay, read all through the other post, so decided to check mine out and no one talked about the 3rd bonding place; the inverter.  I isolated every thing and checked the generator out (wrico 8kw) and it is bonded internally. Question #1, is the internal bond enough or should I add my own too?  Next I checked the A/C panel and it showed the ground and neutral were bonded, it was the inverter (I have 2 Magnum MS2000's).  Will this go away when power is back on, they say it is automatic, should I manually disconnect it?

The more I study, the more confused I get,
Ray D

[bobofthenorth]

Somebody will likely chime in who knows how that specific inverter works but my advice is to do what you are doing - check it with a VOM until YOU understand how YOUR system works.  For a long time after we bought our bus we were unable to plug into a GFI outlet because we had no convenient way to shut down our Freedom 25 inverter which is wired in pass through mode.  The internal bond in the inverter would trip the GFI before the inverter relays switched off the inverter.  When I finally replaced the remote monitor panel with a remote control panel and we were able to easily shut it down we also gained the ability to plug into GFI outlets.  I argued with a couple of campground owners and finally quit doing that because I knew how my system worked and I really didn't care whether they did or not.  And to answer your question directly, yes the internal bond in the inverter will lift when the relay switches to shore power.

[bevans6]

The inverter is treated in exactly the same way as the generator or any other source of power.  It must supply the bond of neutral and ground when it is supplying the power.  It must not bond neutral and ground for the main panel when it is not supplying power.  The way I accomplish this is by routing the connection from the inverter to the main panel through an automatic transfer switch that switches both neutral and power (a 120 volt Iota switch, in my case).  When I run from shore power, the pedestal bonds neutral and ground.  When connected to the generator, it bonds neutral and ground, and when I am running from the inverter, it bonds neutral and ground.  If nothing is supplying power, then neutral and ground are not bonded.

Brian

[Sean]

Okay, read all through the other post, so decided to check mine out and no one talked about the 3rd bonding place; the inverter.

That is because it has been discussed extensively in many, many other threads on this board -- check the archives.  It is a very different subject than the one we've been discussing lately about using the bus to power the house.

The short answer is that the inverter should provide the bond when it is providing power, and not provide the bond when it is passing the power through from another source upstream such as shore or generator.  Modern inverters often have an automatic relay to implement this "switchable" ground-neutral bond, however some older models need to have this capability added externally.  I am away from my files so I can't answer for your Magnums but I suspect they have the capability built in.

As Bob wrote, this type of switchable bond often trips GFCI shore power pedestals.  There are ways to work around this if it is a problem for you, depending on the specifics of your particular inverter installation.  Shutting off the inverter before connecting to the pedestal works for his installation, for example, but does not work for mine.

... is the internal bond enough or should I add my own too?

There should never be more than one single bond.  So no, do not add another bond.

-Sean
http://OurOdyssey.BlogSpot.com

[Ray D]

Learned something here, the inverter is bonded till you get power from shore or generator, than it opens so it is not bonded, so its default is bonded.  I thought my generator was internally bonded, but it wasn't, I did not take the hot lead off the generator and was getting back feed which made it look bonded, so I am bonding the generator.  Question now is, is there a way to check what is bonded with power on.  It would be nice to check this every once in a while to make sure the relay in the inverter is working and the other bonds are okay?

Ray D