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AnimalHungry's avatar
AnimalHungry
Explorer
Jul 12, 2017

Inverter sub-panel - what to do with ground wires

Hi all - I'm new here and have a question about wiring a new sub-panel for my inverter. I have an automatic transfer switch into which I've fed the inverter output and the shore power from the main panel. The output of the transfer switch goes into my new sub-panel (wires on the left-hand side of the panel). I have two breakers which supply the GFI and non-GFI receptacles only - all other devices are still on the main panel.

I've connected the live wire output from the transfer switch to the left-hand live bus, and I've connected the live wires that go to the receptacles to the output of the breakers. All three neutral wires I've connected to the neutral bus at the top, and then I've used a wire but to tie together all three ground wires.


http://imgur.com/a/hfDay

My question is what should I do with the ground wires? The grounds for the receptacles are both connected to the ground bus in the main panel, so I think I don't need to do anything else, but I'm not sure and want to be safe.

Cheers
Simon
  • AnimalHungry's avatar
    AnimalHungry
    Explorer
    Jul 12, 2017
    wa8yxm wrote:
    The Sub Panel should have two bus bars. One for Neutral, one for Ground

    You connect the ground wires in the sub panel just like you do in the Main

    If there is only one bus then you bond all the ground wires with a split bolt

    That INCLUDES the one from the inverter.

    On the inverter you should have the option to bond neutral to ground... or not

    If the inverter has power pass through.. it will bond ground out to ground in when passing through.. The option only applies when inverting.


    Thanks. The inverter manual says it wants an 8ga ground bond, which I've connected to the chassis. The output from the converter feeds into the transfer switch (which has a plastic case) and all the grounds in the transfer switch are connected together. Then the output from the transfer switch feeds into the sub-panel where all the grounds are tied together and I'll bond them to the metal case of the sub-panel. Then those grounds find their way to the chassis via the main panel. Is that what you mean by grounding the inverter?

    Cheers
    Simon
  • wa8yxm's avatar
    wa8yxm
    Explorer III
    Jul 12, 2017
    The Sub Panel should have two bus bars. One for Neutral, one for Ground

    You connect the ground wires in the sub panel just like you do in the Main

    If there is only one bus then you bond all the ground wires with a split bolt

    That INCLUDES the one from the inverter.

    On the inverter you should have the option to bond neutral to ground... or not

    If the inverter has power pass through.. it will bond ground out to ground in when passing through.. The option only applies when inverting.
  • enblethen's avatar
    enblethen
    Nomad
    Jul 12, 2017
    Connected to other grounds is correct. One single ground system.
    Make sure there is no Bonding screw in the sub-panel.
  • AnimalHungry's avatar
    AnimalHungry
    Explorer
    Jul 12, 2017
    time2roll wrote:
    Yes all grounds tied together. All metal boxes grounded. Any equipment chassis ground should be connected.

    Ground always separate from the neutral in the RV.


    Thanks! Since the main panel is bonded to the RV's chassis and I have grounds from the main panel into the sub-panel, I'll just bond the grounds in the sub-panel to its metal box then I'm done.

    Cheers!
    Simon
  • time2roll's avatar
    time2roll
    Nomad
    Jul 12, 2017
    Yes all grounds tied together. All metal boxes grounded. Any equipment chassis ground should be connected.

    Ground always separate from the neutral in the RV.
  • AnimalHungry's avatar
    AnimalHungry
    Explorer
    Jul 12, 2017
    MrWizard wrote:
    as long as all the grounds are connected together you are good


    Thanks!
  • AnimalHungry's avatar
    AnimalHungry
    Explorer
    Jul 12, 2017
    2oldman wrote:
    You're sure you want to go the sub-panel route?


    I've already done it. It was a pretty easy install and avoids any manual switch throwing, which is great for the wife :-)

    Cheers
    Simon
  • MrWizard's avatar
    MrWizard
    Moderator
    Jul 12, 2017
    as long as all the grounds are connected together you are good

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