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Electrical Plan Review

4K views 5 replies 4 participants last post by  sschefer 
#1 · (Edited)
I'm getting ready to install the electrical stuff and I have a few last minute questions I'm hoping the forum can help me with.

My plan is similar to Dave Orton's except that I'm going with a common ground. Why?... My thought is it's more common ;) At least that's the conclusion I've made. Most systems regardless of whether the positive terminals are joined seem to have a common ground.

The guts of my electrical system sit above the driver's wheel well and I'm running a 2awg cable from the 3 CCP (180Amps) to this area. I was planning to ground my system to the grounding point between the two seats but after lifting up the vinyl floor I realized the bolt is the same size at the one used in the grounding points towards the rear of the van. I was expecting something more heavy duty. Some folks have used the park brake as a ground point, however I'm somewhat opposed just because it's not ford BEMM recommended. I thought the grounding points towards the rear of the vehicle (GP26-GP31) were too small and the sheet metal seemed flimsy for a 2awg cable. Is this really an issue? It would be more convenient for me to use the ones in the rear.

While were on the topic of grounding, my 3 main components (Inverter/charger, inverter, and solar controller) all have a separate ground terminal. When do these come into play? Should I be using these?

Attached are two different electrical diagrams, "A" and "B", that have different grounding paths.
-- "B" seems to be the more common solution where the negative terminals all share the same bussbar regardless of power source.
-- "A" (not even sure if this is a feasible option) has the grounding terminals connected to a bussbar for the 2 device's connected to the house battery, then connected to vehicle chassis. The inverter that uses the vehicle battery would not need grounding.

I'm having trouble understanding how the grounding should be done and I would really appreciate any feedback/critiquing. Note: the parts are all purchased so I'm past the stage of using a B2B charger or combiner to charge from vehicle.

Thanks in advance!
 

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#2 ·
The normal RV has to ground the house 12 volt because the house battery is directly connecting to the vehicle battery through a relay for charging. The ground is required when you connect the two batteries together. With a vehicle powered inverter used for charging, the house 12 volt system does not need to be grounded to the chassis. You do have to use two wires to every house load. The vehicle does not need to know there is a house 12 volt system.

For the vehicle powered inverter I used the 3/8" dia. hole in the emergency brake support bracket. Hole is located between the emergency brake and the driver seat base. My 1000 watt vehicle powered inverter works fine using that ground location. The vehicle powered inverter must be grounded to the chassis to complete the circuit.

My understanding is the ground lugs on the inverters are a ground for the case and are required by code. I have asked my inverter manufacturer's if they must be grounded. My understanding is it is a housing ground without any internal wiring connections. They are definitely required if the inverters are mounted on a wood structure. In my case both inverter housings are bolted to the 80/20 framework. The 80/20 framework is grounded to the chassis at one location. I did not use the two inverter ground lugs.

You also need to be concerned about bonding. Your 120 volt system should only be bonded in one location. If you are on shore power that bond is done in the shore power wiring. Inverters make a bond internally when they are running. The bond is broken if the inverter is off. In my cast the Magnum MMS1012 breaks the bond if it senses 120 volt AC shore power and transfers that through the unit. I use a 3 position selector switch to select real shore power or "shore power" from the vehicle powered inverter. The selector switch isolates the two power sources. Only one can be active.

I am not an expert on electrical so use this information with that in mind.
 
#3 ·
There's a bunch of ways to do what your doing. In my purest moments I balked at having any interaction between the house and vehicle batteries. In the end I decided that a common ground (negative) would not be a problem. Like Dave say's there are ways to get what you want without it and they seem to work quite well.

There is only one thing that I might change in your diagrams and that is the two pole AC source switch. I would automate that with an AC transfer switch such as the one that I use: https://www.amazon.com/s/ref=nb_sb_noss?url=search-alias=aps&field-keywords=AC+Trasfer+switch. They are simple to install but do take up some space.
 
#5 ·
Thanks for the replies!

For connecting the 1000w vehicle inverter, are the ground locations at the back of the van equivalent to the one between the front seats? I'm wondering if one is preferred over the other.

All my devices will be mounted to a plywood panel. Per orton's comment, sounds like I need to connect the grounds like shown in diagram A.
 
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