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  • Grounding and DC Returns

    Hi All,

    I'm in the process of replacing my batteries with lithium along with a solar and Victron install. I'm pretty solid on almost all of the install, but find my self questioning the grounding process, especially after seeing how GD installed the stock components. I'll try my best not to muddle AC grounding, DC returns, and bonding.

    Currently, from what I can see, the electronics are "grounded" in five locations. The ATS, inverter, and converter all have a solid bare copper wire grounded to the chassis. In the same area, a bus bar filled with what I figure are the DC returns from the breaker/fuse panel also has a wire from it bolted to the chassis. In the front compartment, the battery negative, along with the returns from the levelers pump and a handful of other DC components, are all bolted together to the chassis.

    As part of my install, the stock batteries will be removed from the front compartment and the new batteries, along with the Victron components, will be installed in the basement next to the ATS and circuit panel back. The new inverter and charge controller will have their cases grounded to the negative bus bar on a Lynx Distributor. A single ground from the Lynx Distributor negative will then be bonded to the chassis.

    My concern is what others have described as "ground looping". With this setup, I will have a single ground from all of the new components, however the ATS will still be grounded to the chassis, as well as the busbar of DC returns from the fuse panel and the DC returns in the front compartment which are each separately bolted to the chassis. For the latter, my assumption is they will be using the chassis as the DC return. My question is, should I eliminate these two locations where the DC returns are bonded to the chassis and instead run dedicated lines from them to the new negative busbar? My concern is if I have multiple locations where the system is connected to the chassis that it could somehow get energized in the event of a short.

    And what about the ATS ground? Is that ok to stay connected to the chassis or should I relocate that to the negative busbar as well?

    Thanks in advance for everyone's help.

    -Tim & Amber

  • #2
    Electrically, the chassis and negative bus bar are the same point. Unless Victron specifies a specific wiring convention, you can treat the chassis and the -ve busbar as the same.
    2018 Dodge 3500 6.7 Cummins w Aisin and 9 cup holders
    Not to brag or anything about my finances, but my bank calls me about every day to tell me my balance is OUTSTANDING!

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    • #3
      TimberGRV -- this is a subject that twists me up in knots, so my only input is there's an excellent (free) reference available from Victron. You can get v7 of Wiring Unlimited here: https://www.victronenergy.nl/upload/...limited-EN.pdf

      Chapter 7 has extensive information on the topic.

      Click image for larger version

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      Howard
      Forum moderators are not GD employees--we are volunteers and owners presumably just like yourself. Unless specifically mentioned otherwise, we have nothing to gain should you choose to purchase a product or engage a service we discuss on this forum.

      2017 Ford F-350 DRW, '19 315RLTSPlus

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      • #4
        The only time I needed to be concerned about multiple ground connections and loops was in instrumentation so that induced currents did not interfere with measurement signals. I don't think such a concern exists in power wiring, AC or DC. Multiple chassis ground connections should be ok.
        Ted
        2021 Reflection 310RLS
        2020 F350 PS,CC,LB,SRW

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        • #5
          TedS
          There are ground loop considerations with A/C systems. Like in your house for instance if you have a panel in your garage as well. The neutral is tied to ground, but only at one spot in the main panel where the service comes in. If neutral was tied to ground in the garage panel as well there could be a neutral/ground loop.
          Doesn't apply to 12vdc -ve ground systems.

          Victron MAY have something in their wiring convention like instrumentation though with grounding only one end for a measurement signal? Maybe?
          2018 Dodge 3500 6.7 Cummins w Aisin and 9 cup holders
          Not to brag or anything about my finances, but my bank calls me about every day to tell me my balance is OUTSTANDING!

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          • #6
            That's neutral-ground loop. The neutral carries current and that is the result of voltage differentials which then create current flows in the ground which should not be carrying current. Single-point grounding prevents induced voltage differential which makes current flow where it shouldn't. Old stereo systems sometimes would have a hum because of multiple ground conections.

            on edit. This may be helpful: https://www.controleng.com/articles/...d-their-cures/
            Last edited by TedS; 01-22-2023, 02:10 PM.
            Ted
            2021 Reflection 310RLS
            2020 F350 PS,CC,LB,SRW

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            • #7
              Originally posted by TedS View Post
              That's neutral-ground loop. The neutral carries current and that is the result of voltage differentials which then create current flows in the ground which should not be carrying current. Single-point grounding prevents induced voltage differential which makes current flow where it shouldn't. Old stereo systems sometimes would have a hum because of multiple ground conections.

              on edit. This may be helpful: https://www.controleng.com/articles/...d-their-cures/
              As you said, audio systems have problems with multiple grounds. A vehicle DC ground is different from an AC ground. The DC ground carries current

              John & Kathy
              2014 Reflection 303RLS
              2014 F250 SC SB 6.2

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              • #8
                Originally posted by TimberGRV View Post
                Hi All,

                I'm in the process of replacing my batteries with lithium along with a solar and Victron install. I'm pretty solid on almost all of the install, but find my self questioning the grounding process, especially after seeing how GD installed the stock components. I'll try my best not to muddle AC grounding, DC returns, and bonding.

                Currently, from what I can see, the electronics are "grounded" in five locations. The ATS, inverter, and converter all have a solid bare copper wire grounded to the chassis. In the same area, a bus bar filled with what I figure are the DC returns from the breaker/fuse panel also has a wire from it bolted to the chassis. In the front compartment, the battery negative, along with the returns from the levelers pump and a handful of other DC components, are all bolted together to the chassis.

                As part of my install, the stock batteries will be removed from the front compartment and the new batteries, along with the Victron components, will be installed in the basement next to the ATS and circuit panel back. The new inverter and charge controller will have their cases grounded to the negative bus bar on a Lynx Distributor. A single ground from the Lynx Distributor negative will then be bonded to the chassis.

                My concern is what others have described as "ground looping". With this setup, I will have a single ground from all of the new components, however the ATS will still be grounded to the chassis, as well as the busbar of DC returns from the fuse panel and the DC returns in the front compartment which are each separately bolted to the chassis. For the latter, my assumption is they will be using the chassis as the DC return. My question is, should I eliminate these two locations where the DC returns are bonded to the chassis and instead run dedicated lines from them to the new negative busbar? My concern is if I have multiple locations where the system is connected to the chassis that it could somehow get energized in the event of a short.

                And what about the ATS ground? Is that ok to stay connected to the chassis or should I relocate that to the negative busbar as well?

                Thanks in advance for everyone's help.

                -Tim & Amber
                Tim,

                I left the ground from the 7 way connected in its original location. When my Converter, Battery and DCDC charger were installed in the passthrough, there were two busbars installed close by. All grounds were connected to the negative busbar and ran down to the chassis with 4awg welding cable. I've not ran across any issues.

                Jim

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                • #9
                  Originally posted by Jkwilson View Post

                  As you said, audio systems have problems with multiple grounds. A vehicle DC ground is different from an AC ground. The DC ground carries current
                  True. The DC current has a direct path to the battery. The DC circuit negative can have a common connection to AC ground with no problem unless you connect another part of the AC circuit to the battery positive and create a continuous path for DC where it doesn't belong. Something would get fried.

                  All ground connections should have as close to same voltage potential, in this case 0, as possible. A single connection point would be ideal, but not necessary here. Unless connected to shore power, trailers are floating systems.
                  Ted
                  2021 Reflection 310RLS
                  2020 F350 PS,CC,LB,SRW

                  Comment


                  • #10
                    Very glad I found this thread… but for my clarity can someone confirm the following?

                    I am not doing a multiplus just yet. I sent my WFCO converter off to get reflashed for lithium. My current understanding is that if I connect everything to the lynx (negative and positive) including the 12v panel then I can get rid of all the bare copper grounds from converter, panel and solar charger and everything will be grounded through the Victron lynx….
                    Attached Files
                    • 2023 Imagine 2800BH
                    • 2013 GMC Sierra 2500 6.6 Duramax (LML)
                    • Family Travels with kids and dog
                    • Love cool upgrades

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                    • #11
                      Originally posted by AAMAFIGHTER View Post
                      Very glad I found this thread… but for my clarity can someone confirm the following?

                      I am not doing a multiplus just yet. I sent my WFCO converter off to get reflashed for lithium. My current understanding is that if I connect everything to the lynx (negative and positive) including the 12v panel then I can get rid of all the bare copper grounds from converter, panel and solar charger and everything will be grounded through the Victron lynx….
                      Yes but you will still want a chassis ground.

                      Brian
                      Brian & Michelle
                      2018 Reflection 29RS
                      2022 Chevy 3500HD

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                      • #12
                        Originally posted by AAMAFIGHTER View Post
                        Very glad I found this thread… but for my clarity can someone confirm the following?

                        I am not doing a multiplus just yet. I sent my WFCO converter off to get reflashed for lithium. My current understanding is that if I connect everything to the lynx (negative and positive) including the 12v panel then I can get rid of all the bare copper grounds from converter, panel and solar charger and everything will be grounded through the Victron lynx….
                        Can you clarify what you mean by "ground"?

                        When referencing 12vDC, the negative side is (IMHO) better referenced as the -12vDC return.

                        Ground is a term best used (again, IMO) with 120vAC wiring. The ground in a 120vAC system is the bare copper wire typically found in a three strand romex (hot = black, white = neutral, and bare or green = ground).

                        These terms often gets interchanged because the trailer frame is used as both a -12vDC return (think of the frame as a big 'ol fat wire) and also as a connection point for the 120vAC ground.

                        Have you sketched out a wiring diagram on your trailer's OEM configuration and the end state wiring? There's many here who can review if you'll take the time to do so.

                        Howard

                        Forum moderators are not GD employees--we are volunteers and owners presumably just like yourself. Unless specifically mentioned otherwise, we have nothing to gain should you choose to purchase a product or engage a service we discuss on this forum.

                        2017 Ford F-350 DRW, '19 315RLTSPlus

                        Comment


                        • #13
                          Originally posted by Country Campers View Post

                          Yes but you will still want a chassis ground.

                          Brian
                          Right! Very sorry for not clarifying but the lynx will be grounded via 4/0 wire from the center lug to a chassis ground. In that instance my thinking is correct?
                          • 2023 Imagine 2800BH
                          • 2013 GMC Sierra 2500 6.6 Duramax (LML)
                          • Family Travels with kids and dog
                          • Love cool upgrades

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                          • #14
                            Originally posted by howson View Post

                            Can you clarify what you mean by "ground"?

                            When referencing 12vDC, the negative side is (IMHO) better referenced as the -12vDC return.

                            Ground is a term best used (again, IMO) with 120vAC wiring. The ground in a 120vAC system is the bare copper wire typically found in a three strand romex (hot = black, white = neutral, and bare or green = ground).

                            These terms often gets interchanged because the trailer frame is used as both a -12vDC return (think of the frame as a big 'ol fat wire) and also as a connection point for the 120vAC ground.

                            Have you sketched out a wiring diagram on your trailer's OEM configuration and the end state wiring? There's many here who can review if you'll take the time to do so.

                            Howard
                            I have done my own sketch of what I found when I started tracing out my electrical of the oem trailer elec. I think that’s what you mean. If you are talking about my new set up I can do that as well but it’s pretty simple. Converter, dc panel, solar all connected to a Victron lynx via red and black wires. Lynx connected to battery bank (200ah battleborn). Lynx grounded or to chassis via 4/0 copper wire. I’ll get a sketch on here in a bit when I get to work.

                            thank you Grand Design Forum for the help!!!
                            • 2023 Imagine 2800BH
                            • 2013 GMC Sierra 2500 6.6 Duramax (LML)
                            • Family Travels with kids and dog
                            • Love cool upgrades

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                            • #15
                              From what I know about the systems, as long as the battery is connected to the shunt fist so all power draws go through the shunt it will read power consumption.
                              Joseph
                              Tow
                              Vehicle: 2024 GMC K3500 Denali Ultimate Diesel
                              Coach: 303RLS Delivered March 5, 2021
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