What are the risks to not upsizing the chassis ground to match new power system?

[mantis_solar]

I'm looking for some electrical insight. I'm (slowly...) upgrading the power system in my trailer to:

• 2x230 ah Lithium batteries
• 1200 VA Victron inverter
• Lynx distributor
• (bunch of panels, not germane to this question)

1/0 AWG cables from the batteries to the Lynx, 200a MBRF
2 AWG cables to the inverter (biggest it can handle), 4 AWG ground cable, 175a Mega fuse.
My question is around grounding the bus bar to the chassis. The stock chassis grounding wire from the existing bus bar is 8 AWG. Per the design I'm following, I should do 2 AWG (1/2 the battery) to the chassis to match the batteries. The issue is that it looks like a royal PITA to route that cable. The hole on the bottom of thee trailer that has everything coming out is filled with foam. OK, I can chip that out and refill it. But it's really hard to reach behind the cabinets and get to that cable routing. How much risk is it living with 8 AWG? For context I'm an engineer and I Really like having things over dimensioned. I'm leaning toward doing it, but I figured I ask for some perspective.

 

[Dave in AZ]

The engineer reply: the 8awg looks good, the rest of the system is over-engineered by 6awg

 

[Reed Cole]

What is the purpose of this "ground wire"? Is it a return path for any of your circuits, or for safety in case a bare wire touches the body of the vehicle or one of your components?

 

[mantis_solar]

The engineer reply: the 8awg looks good, the rest of the system is over-engineered by 6awg

How can it over engineered if it needs to handle loads like 150 amps?

 

[mantis_solar]

What is the purpose of this "ground wire"? Is it a return path for any of your circuits, or for safety in case a bare wire touches the body of the vehicle or one of your components?

Every RV power system design I see has a chassis ground from the bus bar. Closest you can get to earth ground in a vehicle. Many of the components (Inverter, solar charge controller) also have a ground line.

 

[zanydroid]

Every RV power system design I see has a chassis ground from the bus bar. Closest you can get to earth ground in a vehicle. Many of the components (Inverter, solar charge controller) also have a ground line.

That doesn’t answer the question and is somewhat contradictory to itself.

Put another way: Does it carry real, operating current or just fault current?

 

[mantis_solar]

That doesn’t answer the question and is somewhat contradictory to itself.

Put another way: Does it carry real, operating current or just fault current?

Fault current.

 

[zanydroid]

What fault current is there going to be for your DC side (looks like 175A)? And how does that compare to what the tables say about fault current on #8?

Under NEC #8 would be too small. But cars are not houses.

 

[Dave in AZ]

How can it over engineered if it needs to handle loads like 150 amps?

Dude, it's a standard engineer joke...
Pessimist looks at half glass of water and says it is half empty. Engineer looks at it and says the glass is overengineered by 100%...