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I am converting a 2022 Ford Transit Van and need some help with the electrical. I’ve attached my electrical wiring diagram and solar diagram as well as what wire sizes I am running, length and fuses.
I am not an electrician and planning to install myself but want to make sure that I have sized everything correctly.
I also have a few specific questions:

In my AC panel if a load is going to draw 15amps is it better to use a 20amp breaker?
How many outlets can I have on one 15amp or 20amp breaker?
Can you have multiple loads on 1 DC circuit? i.e. 5amp lights and 2 amp lights on the same circuit?
Do I need a fuse on the Solar connection to the RedArc Manager30?
Will using a 250Amp circuit breaker on the Inverter (+) to busbar (+) work?
Do I require a fuse or surge protector from the AC Panel to the Transfer Switch?
The RedArc Manager30 AC Outlet is supposed to plug into something (not inverter) to charge the system. I want to run wire (not sure what size) from the shore power hookups on the transfer switch to a GFCI 15W outlet to plug the AC outlet into it so that when I plug into Shore Power the TS-30 switches from inverter to shore power then the charger will kick in. Will this setup work? What gauge of wire would be best to run from TS-30 to the GFCI 15W outlet? Would I need a fuse or circuit breaker?
I am wondering what size wire to use for Chasis ground:
  • Busbar (-) to chasis: can I use 4AWG or does it need to be 2AWG?
  • Inverter (-) to Chasis?
  • TS-30 ground to Chasis?
  • AC Panel to Chasis?

Please have a look at my system and let me know if you have any recommendations, concerns and if you can answer my questions.
 

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In my brick and mortar house I have 10 outlets on each 20 amp breaker, These are all bedroom bathroom livingroom outlets without much real loads on them. The kitchen outlets are on two 20 amp breakers.
For a camper van I would think all you would really need is a outlet strip with about six outlets on it, They usually come with their own built in circuit breaker.
I have a 2,000 watt inverter and that is enough power to power one outlet strip.
 

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Just looking it over... a few things... I'll have to look more...

FWIW, there are formulas for all the cable stuff... but I usually look up tables that seems easy-ish to look at. But the tables vary a lot because there are technically a lot of variables in the cable: temp rating of the insulation; number of strands in the cable; exact makeup of the metal in the cable; how much voltage loss (and heat) can or will be tolerated. I lean toward following the conservative estimates; but this is your call.

Maybe worth some basic notes:
  • cable size should support the load with adequate room to spare (voltage loss / distance / heat charts and all that)
  • fuse and breakers are sized for the cable ampacity and are typically 1.25-ish greater (if the ampacity is 100A then 125A fuse/breaker - not just sized to fit the load, ideally - can go less but not more to be safe)
  • different types of fuses and breakers behave VERY differently; I am pretty ignorant on this... other folks on this site are top-of-the-head experts - I try to follow their wisdom or look things up as much as possible

Ampacity defines the cable's carrying capacity (based on size and other details including insulation rating, stranding, composition, and proximity to other cables); but it does so in absence of voltage loss. Voltage loss at a max ampacity can be 10% ore more in some cases - which means the cable gets warm, the voltage drops, AND the actual amperage for a given load goes up. (100A @ 12VDC is ~1200W; 100A @ 14VDC is ~1400W - conversely, 1500W @ 14VDC is ~107A; 1500W @ 12VDC is 125A - not huge, but not the same - so voltage drop affects amperage at a given wattage load.)


Just a FWIW... typically, 120VAC Romex (house stuff) called 14/3 is actually four wires (red/black/white/green). But I realize some things have been labeled 14/3 that are actually 14/2 (black/white/green)... but in case it confuses anyone.


Agreed with @ranxerox that standard 120VAC (US) is 15A outlets (10 on one circuit is not uncommon - I have no idea of various codes on this) are on a 20A breaker per leg. So... you gonna have more than ten? But plenty of folks build their vans with a breaker per outlet, so... whatever you prefer.


Minor note but... just my thing: am I reading correctly that the max charge rate for the Redarc is 30A @ 12VDC(-ish) regardless of shore / solar / alternator? It says the max output is 520W. Sure is low when you've got 1800-3600W coming in from shore power. And 2000W available at the alternator. 🤔


My other notes so far have to do with cable sizes for a given voltage loss at a given amperage and the accompanying fuses and breakers. The thing is... I can find references (gotta love the internet) that indicate anywhere from 80A to 195A limits for #2 cable. A 2kW inverter is ~175A at 2kW and the inverter will tolerate double that on start-up (so I'd plan for 175-200A). My favorite chart (below) suggests 2/0 for 200A with 3% voltage loss; but for such a short run, you could get away with less, so... that's your call. I run 2/0 for my 2.2kW inverter with less than three feet of cable.

Other stuff is things like a 250A fuse and/or breaker on a #2 or #6 cable. That's not right. Those are too large for that cable's ampacity. I don't have a favorite simple / easy chart for this. But look up ampacity for a given cable size and run the breaker at 1.25 times higher (rule of thumb).

My method: size for voltage loss first, then protect (fuse / breaker / etc) for the cable size. Protection is for cable failure - to assure the protection fails before the carrying line.

Okay... enough.

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Some of these camper van blogs do a pretty good job of explaining electrical, Faroutride got his start on our forum.

 
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