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Old 02-26-2020, 07:52 PM   #1
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Ground Wire

Is It Ok To Ground Wires To ANY Metal Surface Of The Bus Or Does It HAVE To Be The Chassis? I Was Thinking Of Just Drilling A Hole Through The Subfloor With A Self Tapping Screw.
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Old 02-26-2020, 07:55 PM   #2
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You should have more surface area. That’s like just my opinion man. Drill a hole, route to the chassis, sand to bear metal and install a big fat bolt

Bear metal hehehehehehe
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Old 02-26-2020, 08:10 PM   #3
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I guess I should ask what’s it for?
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Old 02-27-2020, 08:16 AM   #4
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For anything expensive, important, or high current

I run the same gauge wires in a pair to complete the full return circuit back to the power source.

I only trust chassis common for returns on cheap, unimportant and low current loads.
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Old 02-27-2020, 10:03 AM   #5
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Originally Posted by NfiniteMile View Post
Is It Ok To Ground Wires To ANY Metal Surface Of The Bus Or Does It HAVE To Be The Chassis? I Was Thinking Of Just Drilling A Hole Through The Subfloor With A Self Tapping Screw.
AC electric or dc electric?

What are you powering and how many watts does it consume?
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Old 02-27-2020, 12:00 PM   #6
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For anything expensive, important, or high current
Can I get your rationale on this?

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Originally Posted by john61ct View Post
I only trust chassis common for returns on cheap, unimportant and low current loads.
Now I don't do any direct chassis common connections on my subpanels- in all those places I've ran two wire DC. But I do have my main negative bus bar connected to chassis.


I have AC ground to chassis (for GFI protection), 24V solar negative to chassis, and bus bank negative to chassis. Most of the electrical noise seems to come from 12v appliances on the main DC fuse panel (and its in no short supply- I had to switch to a digital audio amplifier).
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Old 02-27-2020, 01:30 PM   #7
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I'm not talking about **also** tying the negative return busses etc into chassis common as a reference in multiple locations, that's fine.

Just not relying on chassis paths **as** the negative return for critical circuits
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Old 02-27-2020, 01:30 PM   #8
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Originally Posted by john61ct View Post
For anything expensive, important, or high current

I run the same gauge wires in a pair to complete the full return circuit back to the power source.

I only trust chassis common for returns on cheap, unimportant and low current loads.
I have done it this way too, but it is important to note that return trip distance should be used when calculating wire size.

If its 20' from the panel to the appliance, then use 40' on the chart to get the proper wire size for the anticipated amp draw. This is how its done in the marine world as chassis grounds aren't an option. They also have excellent insulated 2 conductor stranded cables as well.
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Old 02-27-2020, 01:33 PM   #9
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When I replied I was thinking battery bank because I got that on the brain.

I’m pretty sure it’s common practice to run grounds back to a main bus to make troubleshooting easier.

Of course if you have really big wires to run you can save some money by using the chassis.
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Old 02-27-2020, 02:41 PM   #10
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You just need good connections, I think. This is why I never go from appliance directly to chassis, I go from appliance to a fuse panel with negative, and the fuse panel negative has a beefy cable going to a solid, clean, reliable contact point on either the chassis or cabin. Its much easier to get it right once, the first time.
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Old 02-27-2020, 03:20 PM   #11
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Between the House bank (or whatever source) and the distribution points is of course most critical and highest current.

And yes wire sizing need actual RT distance.

BSS Circuit Wizard is excellent.
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Old 03-08-2020, 09:16 AM   #12
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Anybody willing or able to post some pictures of how their ground to chassis looks or is set up? I’m pretty sure I get it, but That’d be really helpful for us visual learners out there.
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Old 03-08-2020, 10:36 AM   #13
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I've got a 2 AWG battery cable bolted to one of the bolt holes for the chair rail.. Easy peasy.
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Old 03-08-2020, 02:37 PM   #14
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Originally Posted by Willie_McCoy View Post
I have done it this way too, but it is important to note that return trip distance should be used when calculating wire size.

If its 20' from the panel to the appliance, then use 40' on the chart to get the proper wire size for the anticipated amp draw. This is how its done in the marine world as chassis grounds aren't an option. They also have excellent insulated 2 conductor stranded cables as well.
What chart are you referring to?
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Old 03-08-2020, 02:37 PM   #15
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Chart?

Quote:
Originally Posted by Willie_McCoy View Post
I have done it this way too, but it is important to note that return trip distance should be used when calculating wire size.

If its 20' from the panel to the appliance, then use 40' on the chart to get the proper wire size for the anticipated amp draw. This is how its done in the marine world as chassis grounds aren't an option. They also have excellent insulated 2 conductor stranded cables as well.
What chart are you referring to?
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Old 03-08-2020, 06:21 PM   #16
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Best to use Blue Sea Circuit Wizard app.
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Old 03-08-2020, 10:55 PM   #17
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Originally Posted by rydawg3000 View Post
Anybody willing or able to post some pictures of how their ground to chassis looks or is set up? Iím pretty sure I get it, but Thatíd be really helpful for us visual learners out there.
Here is the only shot I have of the grounding wires. Trace the bright green wire to the left and you will see the grounding lugs used to ground everything to the chassis.


20181107_170704 DC Wiring - Underside.jpg
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Old 04-17-2020, 02:09 PM   #18
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Here is the only shot I have of the grounding wires. Trace the bright green wire to the left and you will see the grounding lugs used to ground everything to the chassis.


Attachment 42105
Thanks a lot, that is very helpful indeed. Is the green wire the ground from your AC panel's Ground Bar Terminal? What are the other connections you have grounded there? Looks like the ground connections for all of our 12v things coming from the bus batteries and engine.
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Old 04-18-2020, 03:00 AM   #19
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Quote:
Originally Posted by rydawg3000 View Post
Thanks a lot, that is very helpful indeed. Is the green wire the ground from your AC panel's Ground Bar Terminal? What are the other connections you have grounded there? Looks like the ground connections for all of our 12v things coming from the bus batteries and engine.
The wire bundle at the top are positive cables and the ones that swing lower are negative cables.. All are DC.


The green wire is the ground for the inverter/charger. The AC load panel is grounded a another location, actually to the body. In the same bundle as the green wire is a black wire about the same size as the green wire and below the green wire, this is the ground for a DC panel I added for the house side.


I ran parallel 2/0 wires for both the positive and negative between the inverter (up in the cab) as well as parallel 2/0 runs for the house batteries from the second alternator and between the house batteries in the battery box. I also ran parallel 2/0 cable between the batteries in the chassis bank as well. I figured it was easier to run two 2/0 cables than one 4/0 cable ... and the parallel 2/0 combine to act as one 5/0 cable electrically. I left the 2/0 run from the chassis alternator to the chassis battery bank as-is because it was doing what it is designed to do.


So, it looks like there is a lot more going on with that picture than it really is.


Here is what is happening on the other side of that picture (in the battery box):
20181029_152113 Batteries in New Tray.jpg
That "thing" in the middle is the battery isolation relay.
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Old 04-18-2020, 08:53 AM   #20
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Awesome! Thanks a lot, that really helped clear the dust for me. Now I realize I’m looking at the outside of the steps in the background!
Our power hub for the house will be in the rear of the bus and I have a joint Ac/Dc distribution panel so I think my only ground needed to run is from inside from the ground bus bar at the panel to the chassis at the moment.

We will only be wired up for shore/generator power for the meantime, adding battery bank and solar after we move in. I imagine at that phase I will probably have something else that will need to run through the floor to the chassis for grounding but we will leave space and address that when the day comes!

Also, mad kudos for making clean, even lengths in your beefy cables.
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