Help with Wiring New 12v System

[awhit22]

Cross posted on a couple sites...

Hello all. My first post here. I am working on a project to install electrical system in a converted cargo trailer. New to DC wiring. Trailer is starting from scratch with no existing power. Using a Progressive Dynamics 4045KA converter / control center and 100a battery (I will eventually have more than one).

I think I have it mostly right, but I'm confused on the ground connections to the chassis. I've done research, but nothing is super clear. I plan to run a ground connection for the AC side. I also understand I need to ground DC negative side. But I don't know where to connect that in the system. I will have a central bus bar for all negative connections. I also want to put in a shunt for battery monitoring. So I am thinking, the ground to chassis should either go on the negative bus bar, or on the load side of shunt. I drew out what I think should be done. Hoping someone here, can give me some clarity for fix my thinking. Yes this drawing is probably overkill for such a simple project, but it's how I keep it straight in my head. 🙂 AND I can't find anything like this online in simplistic form, so hoping someone here can use it.

[JimK-NY]

I don't have a favorite calculator. Anyway, if you have a 45amp system, I would wire for that maximum amount. So that would be 5' away for a total pos-neg wire run of 10 ft. 8 gauge is not excessive. How much power you draw is only one consideration. You need to wire the system for the max charging at 45 amps. If your distance estimate is off a couple of feet, that would put you closer to 6 gauge wiring.

[awhit22]

JimK-NY wrote:
Looks like you had your questioned answered. Since you are new to DC wiring, I have another suggestion. Pay attention to wire gauges. 12v systems carry 10x the amperage of a 120v system to provide the same power. Use a wire gauge calculator and don't skimp. Even the 8 gauge to the battery may not be enough depending on the distance to the power unit.

Thanks for the follow up and suggestion. The distance from battery to the control center is only about 5ft. In this case the biggest thing I am planning to power is a laptop and a monitor, then some LED lights and an over head RV max fan. The control unit is 45a max. Couple weeks ago I ran it thru an online calc that suggested 8 or 10 AWG from battery. Is there an online calculator you like over another? I just picked one from the google search.

[JimK-NY]

Looks like you had your questioned answered. Since you are new to DC wiring, I have another suggestion. Pay attention to wire gauges. 12v systems carry 10x the amperage of a 120v system to provide the same power. Use a wire gauge calculator and don't skimp. Even the 8 gauge to the battery may not be enough depending on the distance to the power unit.

[theoldwizard1]

Remember, DC ground carries current. AC ground should not !!

Spend the extra $$$, and use "marine" wire/cable. It is pre-tinned and will not corrode. I would also use stranded cable for the AC circuits. Personally, I use uninsulated connector and cover them with marine/dual wall heat shrink.

[awhit22]

Thank you for the confirmation and quick reply. Appreciate it.

[enblethen]

Ground needs to go to the rig's frame.
Definitely not to the 120 volt neutral buss bar.
As in red circles, it is clear to run to rig's frame. You should run two ground wires with separate connections to frame.
Normally ground wire is oversized such as #6. Make sure frame is clean. Solid wire is preferred. No crimp connections.