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Grounding, Breaking and Clamping my system - Do I have this right?

Dhowman

San Diego, California
Joined
Dec 29, 2019
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295
Location
San Diego
So, have been trying to figure out (here and here) how best to "short circuit" and "surge" protect my system. Have gotten lots of great info and am trying to apply what I've understood to my particular set up.

Here's my first crack at it (below). Pleeeze ... if you see something I've gotten totally wrong, don't hesitate to say so in no uncertain terms. You won't hurt my feelings.

This is a simplified version of a more detailed schematic I've posted elsewhere (see my sig). What follows after that is a description of the short and surge scenarios that I think this design will cover and that references the circled letters.

1584894229469.png

As you can see, I've decided not to isolate my system and grounded the NEG side, so GRND and NEG below are the same thing. I've chosen this so as not to have to break both POS and NEG sides at all the breakers.

Shorts to GRND/NEG scenarios:
  1. A > B: This is the only scenario I haven't a clue how to address. What would happen to my panels and DSSRs if/when this happens? Should I fuse the POS line at the panel?
  2. B > D, E, G: Breaker #1 trips.
  3. C > B, D, E, G: DC Fuse at Battery blows.
  4. E > F: Breaker #2 trips.
  5. G > H: Breaker #3 and/or GFCI trips.
I think that covers all possible scenarios, no?

Surge protection scenarios: My PV cables in the event of a nearby strike are probably the biggest source for these types of events (won't ever be on shore power). I've installed an SPD to clamp surges seen at the NEG/POS buses, but wondering if it wouldn't also make sense to add another one at the combiner box for my solar panels on the roof (?)

I'm illustrating a GRND BUS in my diagram, but IRL, green wires from Inverter and SPD would simply terminate on the NEG bus bar, yes?

Also, FYI, if I'm ever camped on a mountain top or some other high lightning risk spot, plan to actually ground the truck frame to Mother Earth with a strap and a 4-foot copper spike driven into the ground.

Will move on to the specs for all these devices once I've been able to confirm I've got the right ones in the right spots.
 
DSSR is digital solid state relay?
Where is the solar charge controller?
 
DSSR is digital solid state relay?
Where is the solar charge controller?
Yes, DSSR = Digital Solid State Relay (from Electrodacus)
My "SCC" consists of the DSSRs controlled by SBMS0 (also from Electrodacus). The SBMS0 (my "BMS") sits outside the Load and Charging circuits, so needs no protection (see detailed schematic in my sig).
 
Nice clean intuitive schematic, well done! I don't have any advice to offer, and I've only briefly looked at your schematic, but I'm excited to see how this thread develops, this is a topic of interest to me and something I'm trying to learn more about.

What made you decide on a non-isolated system? I haven't quite been able to get a grasp all the pros/cons of isolated vs non-isolated systems.
 
What does the ground coming off your truck frame signify?

edit: nevermind, i think I found my answer:
Also, FYI, if I'm ever camped on a mountain top or some other high lightning risk spot, plan to actually ground the truck frame to Mother Earth with a strap and a 4-foot copper spike driven into the ground.

This is for lightning protection, beyond lightning I wonder would this effect the other normal functions of your grounding system in any way?
 
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What does the ground coming off your truck frame signify?

edit: nevermind, i think I found my answer:


This is for lightning protection, beyond lightning I wonder would this effect the other normal functions of your grounding system in any way?
Is it such a good idea to earth your truck to an earth spike ? One is normally quite safe in a vehicle sitting on rubber tyres in case of a lightning strike.
Having earthed the vehicle you are providing a low resistance path for the strike whereas it may have struck a tree nearby.
Following.
 
I prefer not to use the vehicle chassis as a negative conductor and always run both wires to all the points. Not only does rust form at the point where you tap off the negative on the chassis but galvanic corrosion takes place at those points leading to high resistance contacts and unwanted volt drops causing equipment not to perform optimally.
Following.
 
What made you decide on a non-isolated system? I haven't quite been able to get a grasp all the pros/cons of isolated vs non-isolated systems.

Is it such a good idea to earth your truck to an earth spike ? One is normally quite safe in a vehicle sitting on rubber tyres in case of a lightning strike.
Having earthed the vehicle you are providing a low resistance path for the strike whereas it may have struck a tree nearby.
Following.

Yeah, still on the up side of this learning curve and may be changing my mind about all that and just isolate everything and add NEG breakers where I already have POS ones.

@pierre Those 4 rubber tires have already failed me once, so just investigating alternatives/other safeguards.
 
Yeah, still on the up side of this learning curve and may be changing my mind about all that and just isolate everything and add NEG breakers where I already have POS ones.

Just read through that thread, some good info there.

You are a bit further along the path of learning about isolated/non-isolated systems. Are there any resources you've come across that you found helpful and would recommend?
 
Are there any resources you've come across that you found helpful and would recommend?
Not exactly. Just bits and pieces here and there from all over (that I've linked to copiously on all those referenced threads) and connecting the dots in my head and from the back and forth w others here. Reading up on Isolated vs Non-Isolated converters gave me a little better understanding of isolated vs Non-isolated systems in general. It's starting to gel, but mostly it's been "seat-o-the-pants" understanding. ;-)
 
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