pure sine wave inverter to a c panel

[windwatcher]

 i have a 24 volt 1800 watt xantrex pure wave inverter. without transfer relay. 120 volt ac hardwired output.
 
 i wrote xantrex and got a response from schnieder electric. so i assume they are happy owners.

 i ask them about proper hookup to a c panel. they told me.

 hook chassis to ground rod      a c   output that feeds panel needs to go to ground rod.

 i wrote back and ask if i should bond neutral to ground and got no response.

 so that is my question should i bond neutral to ground.

 some info on inverter i opened it up and neutral and ground are bonded together.
 also i get 120 volt a c  line to neutral and  line to ground with no load. i have read that neutral and    ground  should be bonded in only one place.  but i do not know if this is so using inverter,

 also should or could i use same ground rod or should it be two ground rods.

 i could not get spell check to work so hope all can be read.

 windwatcher

[windwatcher]

 this would be for a stand alone system. no grid

[dnix71]

Neutral and ground would be bonded at the transformer if you were connected to the grid. In this case the inverter takes the place of the grid, so the bonding is inside the inverter.

The chassis ground connection at the panel is the important thing to get right. And make sure the panel earth is solid. The NEC only requires 25 ohms to ground for residences, but the telcos want 5 ohms or less.

http://support.fluke.com/find-sales/Download/Asset/2633834_6115_ENG_A_W.PDF  Fluke has a good pdf here on how to test earth ground and how to make it meet regs if it is too high.

[windwatcher]

 thanks dnix71 for the information that cleared the bonding issue up for me.

 but i am not clear on chassis ground, are you saying run chassis ground to panel instead of ground rod.
 and hook ground from hardwire to chassis ground at panel. then to ground rod.   

 sorry my brain is well grounded but is does have a short sooo.......

 thanks for the sight i will also study that and will be a great help.


 thanks windwatcher

[dnix71]

The inverter takes the place of the grid so there must be an inverter chassis wire grounded to the earth. The inverter chassis should also be grounded to the inside service panel chassis. The neutral-ground bond is inside the inverter housing (only, no other place!).

You could hook up the inverter chassis to the existing building ground if there is one. You said you are off-grid now, but I didn't know if there was a grid hookup in the past. It used to be people grounded the electrical service to metal water lines but some cities get bent about that now. They don't even like the telcos using city utilities as a ground source.

It is important to make sure the actual earth-spikes and cables are low impedance. In Miami a few years ago a contractor for the county did some half-assed grounding of step down transformers at bus stops and it killed a boy waiting for the bus one rainy day. The bedrock in south Florida is fossilized seashells. Driving a stake into limestone coral doesn't make a proper ground.

The Fluke pdf explains how to check and make a proper building ground so lightning and failing appliances won't harm you inside.

[windwatcher]

 i am on grid but this inverter will be a stand alone system nothing to do with grid or its breaker.

 what i have on inverter, is chassis ground,    out of the hardwired i have neutral, ground and hot.

 what i am not sure about does the ground where it is hardwired if it serves for chassis ground since they are hooked together  inside   of inverter.

 again i will read the sight you gave i am on dial up and it has been loading for a while.

[dnix71]

If this is completely separate then the service panel on this separate system is chassis grounded to the inverter panel. The inverter panel is then earth grounded with copper stakes and cables. The only place the neutral and grounds are bonded is inside the inverter panel. Each wire (hot, neutral and ground) from the inverter is fed separately to the service panel and then separately to the system wiring.

All the system outlet grounds and panel enclosures are electrically connected to each other and grounded together so any faults or lightning strikes travel that path out and into the earth.

[windwatcher]

 

 o k  let me make sure about the ground wire.  from where it comes from where neutral and hot is does it just go to the load without going to ground rod. or do i hook it up with chassis ground inside breaker box. to ground rod.

 thanks for all the info i hope i am not trying your patience to much.

 windwatcher

[dnix71]

The ground wires in your outlets go back to a service panel. They are all tied together on a strip of metal with set screws. That metal strip is mounted with steel screws to the inside of the service panel. If the inverter is mounted with metal conduit next to the service panel that should enough to bond the two panels, otherwise run a wire from the service panel ground strip to the inverter panel's earth ground.

The inverter panel then gets a copper cable from it's earth ground connection and that goes outside into the earth. The Fluke pdf tells how to make the outside stake/copper cable connection so it will protect the system and you and meet the code.

The hot wires in your outlets all go back to breakers in the service panel and the hot bus bar in the service panel is fed from the hot lead of the inverter.

The neutral wires of your outlets go back to the neutral bus bar of the service panel, which is connected to the neutral lead of the inverter. This neutral bus bar must be isolated from the ground and chassis of the service panel.

The inverter (somewhere upstream of it's internal ground/neutral bond) has current sensors. If current is detected flowing down the ground there must be a fault in the system wiring. The inverter should trip out if that happens. OR, the neutral current and hot current are compared and if they are not equal then there is a leak to ground somewhere and the inverter trips off. If you bond neutral and ground anywhere else, this protection system in the inverter will not work and the inverter should refuse to operate.

[windwatcher]

thanks for your time dnix71.  and thanks for sharing what you have with me it has been a great help.

windwatcher