Grounding my van electrical.

[navillus]

The electrical components of my system are run to positive and negative bus bars.
Question: Can I ground the whole system by running a grounding wire from my negative bus bar to a chassis ground? If I do this, do I need to still run separate grounding wires from my solar charge controller, battery converter, and my inverter, or will the bus bar ground cover everything that is wired to them?
Also, how do I size the grounding wire from the bus bar? Thanks!

 

[rmaddy]

Yes, you need to run separate ground wires from the various devices to the negative bus bar. Then one ground wire from the negative bus bar to the chassis. For each device's ground wire I used the same size wire as the corresponding DC wire. For the final ground wire to the chassis I used the same size as the largest battery cable.

Each device has a ground, in addition to the DC wires because the device's ground wire is grounding the device's case. That's a different need than the DC negative wire.

You may find the following helpful:

Grounding Made simpler - Part 4: Mobile systems.

To get the paper, click on the orange button at the top of the screen. The subject of grounding is a complex, multifaceted subject, that is often treated as an after-thought but needs to be considered from the beginning of the design and build...

diysolarforum.com

 

[navillus]

Yes, you need to run separate ground wires from the various devices to the negative bus bar. Then one ground wire from the negative bus bar to the chassis. For each device's ground wire I used the same size wire as the corresponding DC wire. For the final ground wire to the chassis I used the same size as the largest battery cable.

Each device has a ground, in addition to the DC wires because the device's ground wire is grounding the device's case. That's a different need than the DC negative wire.

You may find the following helpful:

Grounding Made simpler - Part 4: Mobile systems.

To get the paper, click on the orange button at the top of the screen. The subject of grounding is a complex, multifaceted subject, that is often treated as an after-thought but needs to be considered from the beginning of the design and build...

diysolarforum.com

Thanks for the response, I appreciate your time.

 

[time2roll]

The electrical components of my system are run to positive and negative bus bars.
Question: Can I ground the whole system by running a grounding wire from my negative bus bar to a chassis ground? If I do this, do I need to still run separate grounding wires from my solar charge controller, battery converter, and my inverter, or will the bus bar ground cover everything that is wired to them?
Also, how do I size the grounding wire from the bus bar? Thanks!

The single ground is fine for the negative wires. However you should still have an independent chassis ground for the metal housing of the device.

 

[navillus]

The single ground is fine for the negative wires. However you should still have an independent chassis ground for the metal housing of the device.

I was looking at epever manual, and I do not see a recommended wire size for grounding the case? Any recomendations?

 

[navillus]

In addition, I cannot find the recommended grounding wire size for my power converter PD9145ALV, have emailed the company and have not heard back, anyone know what gauge this wire should be?

 

[rmaddy]

For each device's ground wire I used the same size wire as the DC wire going to the device.

 

[navillus]

For each device's ground wire I used the same size wire as the DC wire going to the device.

Wow. I have 4/0 to my inverter, is this necessary to ground the case? Renogy is the only manual where I could find a 10 awg case ground recommendation. The other devices do not specify.

 

[rmaddy]

You have 4/0 to your inverter because the inverter may draw around 250A. What if that 250A makes it to the case of the inverter? The ground wire needs to handle that same amount of current. At least that's my logic. But I only have 1/0AWG wire to my inverter so it was no big deal to run a 1/0 wire for ground.

To be honest, for all I know the ground wire could be 18AWG (not likely). But I feel safe knowing I used matching wire size.

 

[John Frum]

You have 4/0 to your inverter because the inverter may draw around 250A. What if that 250A makes it to the case of the inverter? The ground wire needs to handle that same amount of current. At least that's my logic. But I only have 1/0AWG wire to my inverter so it was no big deal to run a 1/0 ground wire for ground.

To be honest, for all I know the ground wire could be 18AWG (not likely). But I feel safe knowing I used matching wire size.

Most equipment I have seen has a mechanical lug for the equipment ground and those lugs typically can not accommodate wires as large as the main lugs.

 

[rmaddy]

Most equipment I have seen has a mechanical lug for the equipment ground and those lugs typically can not accommodate wires as large as the main lugs.

Everything I needed to ground has a machine screw on the case. I simply added a lug to the wire with the correct size hole for the screw.

I just did a quick search and I found this page:

Grounding and Circuit Protection for Inverters and Battery Chargers - Blue Sea Systems

Engineering high quality marine electrical components for safety, reliability and performance

www.bluesea.com

That includes this statement from ABYC:

Install a DC grounding conductor sized not less than one size smaller than the DC positive conductor and have a capacity such that the DC positive fuse has an amperage rating not greater than 135% of the current rating of this grounding wire.

So it seems that if your inverter is connected with 4/0, your ground wire should be 3/0 or larger (4/0).

 

[navillus]

You have 4/0 to your inverter because the inverter may draw around 250A. What if that 250A makes it to the case of the inverter? The ground wire needs to handle that same amount of current. At least that's my logic. But I only have 1/0AWG wire to my inverter so it was no big deal to run a 1/0 ground wire for ground.

To be honest, for all I know the ground wire could be 18AWG (not likely). But I feel safe knowing I used matching wire size.

Fair enough, thank you for your insight.

 

[time2roll]

I was looking at epever manual, and I do not see a recommended wire size for grounding the case? Any recomendations?

The lesser of #8 or one size less than the largest power wire is fine.

 

[navillus]

The lesser of #8 or one size less than the largest power wire is fine.

Thank you for contacting Renogy.

Yes, you are correct a 10 AWG cable wire is the precise size that you can use to ground the 3000w inverter. Have no worries as this is the recommended wire size.

Should you have any other concerns, please reply to this email or call us at 909-287-7100 Mondays through Fridays from 8:30 AM to 3:00 PM PDT. You can use the Case ID provided below as your reference.

 

[DerpsyDoodler]

In addition, I cannot find the recommended grounding wire size for my power converter PD9145ALV, have emailed the company and have not heard back, anyone know what gauge this wire should be?

For inverters they say same size or 1 awg less than the cable powering the device (my manual does). Good rule of thumb to follow.

Can anyone explain what the ramification would be of not grounding the DC negative bus bar? Why should that be done?

 

[navillus]

For inverters they say same size or 1 awg less than the cable powering the device (my manual does). Good rule of thumb to follow.

Can anyone explain what the ramification would be of not grounding the DC negative bus bar? Why should that be done?

Looks like renogy recommends 10awg to ground the inverter case.

 

[time2roll]

Can anyone explain what the ramification would be of not grounding the DC negative bus bar? Why should that be done?

As with any grounding the idea is to avoid you or a stray wire becoming the ground and causing an unintended issue. The hot is protected by a fuse. As long as there are no faults there will be no issues with having an isolated bus. There is no way to cover every possibility, situation and equipment here.

 

[John Frum]

The equipment ground serves 2 functions, maybe more.
1 Keep the system at the same potential as the planet its attached to.
That usually doesn't take a thick wire.

2 Clear a ground fault(allow the over-current protection to trip).
Wire should be big enough to clear the fault without the insulation melting.
This will probably require a thicker wire.

 

[DerpsyDoodler]

As with any grounding the idea is to avoid you or a stray wire becoming the ground and causing an unintended issue. The hot is protected by a fuse. As long as there are no faults there will be no issues with having an isolated bus. There is no way to cover every possibility, situation and equipment here.

Sorry, I don't want to hijack this thread and this question is off topic, so if its not a quick simple answer, would you mind dm? or tell me and I will create a new thread for the question.

Given a choice between having a gfdi on the negative bus vs having the negative bus grounded in the traditional manner (with a low resistance connection directly to ground), which offers more/better protection?

 

[Short_Shot]

Is this thread confusing dc negative with ground and using them interchangeably?

That's kind of inappropriate to do so and it has always driven me nuts that the industry has adopted the term "ground".

DC mobile equipment with a 12 volt vehicle and 12 volt components don't need a "ground" because the negative (which people are calling "ground") is itself at the same potential as the chassis.

My victron stuff for example is all 12v and has no enclosure ground of any sort. It does however have a 12vdc negative connection and this can be ran to a bus bar or any point on a 12vdc negative chassis.

Many times the chassis "ground" is rather poor but suitable upgrades can be done to provide a long lasting, electrically high quality negative path to your alternator and battery or batteries. I for example regularly run 90 amps through my truck chassis with minimal voltage drop, and what drop I do experience is from exceeding my alternator capacity.

If your connection from chassis to battery/alternator is good, then you can "ground" (not actually a ground but rather your 12vdc negative) can be done anywhere that is convenient as long as the connection point is free of paying and corrosion.


Some people will argue about galvanic corrosion but a car, van, or truck is not a boat.

That said:

If you CAN conveniently run everything to a single bus bar please do so. It makes life a lot simpler to have one really good chassis connection to this bar, plus a good lead to your batteries.

You always need a negative connection to your mobile equipment. You do not always need a "ground" because usually that's the exact same, electrically, as your negative lead as long as your vehicle voltage matches your power system voltage.

A 12 volt van with a 12 volt solar system means your negative and "ground" are exactly the same thing.


At the end of the day however, read the manual. Some devices may feature a small chassis ground in addition to a large negative cable even if the two leads are the same potential voltage.