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Apologies if this has been answered but I can’t find it searching. My inverter is bonded. Meaning the ground of the 120v AC outlets connect to the inverter chassis. Do I ground the inverter chassis to the van body/frame or can I wire it to the 12v dc bus bar that is grounded to the chassis. Or neither?


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"Bonded" means the neutral and ground are connected (at the panel/source). The inverter chassis should also be grounded to the vehicle chassis. Directly would be best but via the negative buss bar (That already has a connection to the chassis) would be sufficient.

It's important because UL-458 for mobile inverters allows for 60V on the neutral. These types should not have additional outlets connected. Only use the outlets on the unit.
 

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Discussion Starter #3
"Bonded" means the neutral and ground are connected (at the panel/source). The inverter chassis should also be grounded to the vehicle chassis. Directly would be best but via the negative buss bar (That already has a connection to the chassis) would be sufficient.



It's important because UL-458 for mobile inverters allows for 60V on the neutral. These types should not have additional outlets connected. Only use the outlets on the unit.


Thanks. We have a samlex pst-1500, which has the option the hard wire the outlets to the inverter. I’ll run a separate ground to the chassis to be safe.


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I have a Magnum MS1012 powered by two Crown CR260s. The house batteries were wired totally independent of the van batteries until I installed the Sterling BB1230 which instructs you to run a ground wire from the van bank (-) directly to the house bank (-) bus. So I guess the house bank now shares a ground with the van bank/chassis.

At first I didn't even have the ground on the inverter chassis attached to the van chassis. I know, probably dumb but it was fine for our first two week trip. Hot, Nuetral, and Ground were all three connect directly from outlet to the inverter.

This time around, I did ground the inverter chassis to the van chassis. But if your house bank was 100% independent of the van bank and chassis ground, would you still ground your inverter to the chassis?

If anyone knows that I did that wrong please let me know.
 

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I know I am answering an old post but my understanding is that the house inverter is usually grounded to the chassis, at least that's how I wired up mine.
 

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My guess is that grounding the inverter to the chassis would be good in either independent or ganged systems. If a failure happens inside the device you have plugged in then the current has a path to ground. If the failure is something in your device shorts to the chassis then again there is a path to protect you from the current.
 

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My understanding is the ground terminal on the inverter is to ground the housing to the vehicle. In my case the aluminum housings are bolted to the 80/20 framework which is grounded to the chassis at one location. I did not use the ground terminals on my two inverters because the cases are grounded. Ground terminal should be used if housing is not grounded. Terminals would be used if inverter bolted to wood. Someone please correct me if that is incorrect. Code says you must use the ground terminal.
 

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I looked into this, get the information from people who outfit boats. The RV side is lacking.

The inverter, say 2kw, with 2/0 pos w/175amp fuse & 2/0 neg wire, the chassis gnd post is tiny, maybe 10ga wire? What happens if a catastrophic failure occurs and the +2/0 contacts the chassis with a 10ga gnd wire? red hot glowing wire?

My inverter is mounted on wood so I removed my chassis gnd wire, the thinking is: if the inverter fails and +2/0 contacts an unground case the only thing that will happen is the inverter won't work, replace inverter.

If the +2/0 and -2/0 touch the 175 amp fuse will blow.

I believe in the boating world the chassis gnd should be at least 2/0 back to the battery that way the 175 amp fuse will blow.

Of course do your own research.
 

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While Phil is correct the usual reason for a separate inverter ground wire is for RF shielding. To be effective it needs to be ultra short and make a chassis connection with the shortest possible wire. Some times this is not the same as the place you would want to draw 200A from.
In my install I have a direct (00 wire) connection to the battery for the negative input and then to the chassis. This helps keep the high current noise, on both 12v inputs, out of the chassis. It circulates between the battery and inverter which are a foot apart.
A smaller inverter case ground goes directly to the van floor about 2" away.
There is a small possibility of interference with vehicle electronics if very high DC ground current, from the inverter, pass through the chassis.
Yes there is a possibility of high current in that wire. I would then act as a fuse.

Ron
 

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I looked into this, get the information from people who outfit boats. The RV side is lacking.

The inverter, say 2kw, with 2/0 pos w/175amp fuse & 2/0 neg wire, the chassis gnd post is tiny, maybe 10ga wire? What happens if a catastrophic failure occurs and the +2/0 contacts the chassis with a 10ga gnd wire? red hot glowing wire?

My inverter is mounted on wood so I removed my chassis gnd wire, the thinking is: if the inverter fails and +2/0 contacts an unground case the only thing that will happen is the inverter won't work, replace inverter.

If the +2/0 and -2/0 touch the 175 amp fuse will blow.

I believe in the boating world the chassis gnd should be at least 2/0 back to the battery that way the 175 amp fuse will blow.

Of course do your own research.
I'm out of my element here but isn't a large fuse like that intended for current overload? I think the reason you always see smaller ground wires and terminals almost everywhere (except lightning protection systems) is that they only need to carry enough current to trip the interrupter from a short circuit. Once the circuit breaker is tripped the problem is over with, rather than sinking all that fuse current through a huge ground wire to the chassis? So don't you typically need both a fuse for over-current and a breaker for a short circuit?
 

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Ha!

A fine example of why CrewVanMan should get his Ford buddies to have a factory option for a high power inverter.

My guess is almost everyone would want it.

Inverters are a very common topic here.
.
 

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Better not forget the equipment ground.

That is how this thread ran astray: terminology!
Well, an inverter only has three ground types, a DC ground, an AC ground and the case or chassis ground.


The OP was asking what to do with the chassis ground. That is all.


I say, attach it to the frame of van near the inverter.
 

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I'd trust the boat requirements https://www.bluesea.com/resources/101

Check Boat Wiring Before Installation According to ABYC E-11

1. Before installing a charging device, confirm that there is a good connection between AC and DC grounds. If there is not a good connection, the charger/inverter grounding, when it is installed, may become the main connection between AC and DC grounds and must be sized for the boat's entire electrical system in order to avoid the risk of shock or fire. The AC grounding system and the DC grounding system should be firmly connected at a main grounding bus or at the engine block.,/p>
These connections help prevent faults in a boat's wiring from becoming lethal leakage currents that flow into the surrounding water or energize exposed metal on a boat. Some boat builders omit this grounding connection as a means of reducing galvanic corrosion resulting from coupling to adjacent vessels through the power system. A better way of preventing galvanic corrosion is to install this ground connection and install a galvanic isolator or isolation transformer in the AC power system.

When Installing Charger, Inverter, or Inverter/Charger Follow A-20 and A-25
A-20 and A-25 contain specific installation directions that are not described in E-11.

2. Install the AC wiring to the charger or inverter including an AC grounding conductor of a size equal to the current carrying conductors unless the circuit exceeds 30A, in which case the grounding conductor may be one size smaller (E11.16.1.3.8.2). This is the typical grounding conductor that you would see with any AC appliance and returns with the other AC conductors to the power distribution panel.

3. Install a DC grounding conductor sized not less than one size smaller than the DC positive conductor and have a capacity such that the DC positive fuse has an amperage rating not greater than 135% of the current rating of this grounding wire. As a practical matter, this wire will be much larger than the AC grounding conductor. This requirement is the latest addition to the standards when it was discovered that faults in the DC side of an inverter or charger could provide sustained high currents that could start a fire from overheating the AC grounding conductor.
 

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I'd trust the boat requirements https://www.bluesea.com/resources/101

Check Boat Wiring Before Installation According to ABYC E-11

1. Before installing a charging device, confirm that there is a good connection between AC and DC grounds. If there is not a good connection, the charger/inverter grounding, when it is installed, may become the main connection between AC and DC grounds and must be sized for the boat's entire electrical system in order to avoid the risk of shock or fire. The AC grounding system and the DC grounding system should be firmly connected at a main grounding bus or at the engine block.,/p>
These connections help prevent faults in a boat's wiring from becoming lethal leakage currents that flow into the surrounding water or energize exposed metal on a boat. Some boat builders omit this grounding connection as a means of reducing galvanic corrosion resulting from coupling to adjacent vessels through the power system. A better way of preventing galvanic corrosion is to install this ground connection and install a galvanic isolator or isolation transformer in the AC power system.

When Installing Charger, Inverter, or Inverter/Charger Follow A-20 and A-25
A-20 and A-25 contain specific installation directions that are not described in E-11.

2. Install the AC wiring to the charger or inverter including an AC grounding conductor of a size equal to the current carrying conductors unless the circuit exceeds 30A, in which case the grounding conductor may be one size smaller (E11.16.1.3.8.2). This is the typical grounding conductor that you would see with any AC appliance and returns with the other AC conductors to the power distribution panel.

3. Install a DC grounding conductor sized not less than one size smaller than the DC positive conductor and have a capacity such that the DC positive fuse has an amperage rating not greater than 135% of the current rating of this grounding wire. As a practical matter, this wire will be much larger than the AC grounding conductor. This requirement is the latest addition to the standards when it was discovered that faults in the DC side of an inverter or charger could provide sustained high currents that could start a fire from overheating the AC grounding conductor.
A isolation transformer is a rather expensive piece of kit, I would hook the inverter AC ground direct to the shorepower ground, Or a ground rod as others have suggested.
 

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Wow!
Many people have written entire books on grounding and I've worked with more than one person who claimed I would have to pull their "cold dead hands" of the hardware before they would change the way they did grounding.

Boats need / use an isolation transformer to prevent corrosion due to any ground currents that may circulate between the boat, ground and saltwater. Not an issue for a van.

Ground and AC neutral are problematic because some pieces of equipment connect the two internally (now a rarity) and having a well defined single point of connection between neutral and ground in required to support the operation of ground fault safety devices. Even the schematic shown above may not work depending on what is happening at the AC connection you use. (Check out the Magnum MS series users manuals for more than you wanted to know on this topic.) To be ultra compliant you may need to have a relay that disconnects the ground / neutral connection when connected to outside AC power.

I think these considerations are important, in particular if you have high power inverters, children or are just ultra safety minded.

But, I did the following in my design.
* There is a single point where chassis ground, DC ground and AC ground connect.
* I use heavy gauge cable (00) for the battery / inverter and use a short (18") cable to connect the inverter negative 12/ ground directly to the battery negative so that the higher inverter currents (upwards of 180A) do not flow in the van chassis.
* I treat AC hot and neutral as if they are both hot. (Don't assume neutral is "neutral")
* I almost never connect to outside AC power. When I do I spend time to make sure that the external power is correct. That is only hot is hot, both neutral and ground are less than 10V. I have often seen 60V AC on neutral and wires swapped.
* Floating neutrals or grounds are bad. They can mask serious problems, cause electrical noise and cause erratic operation of almost anything. I have heard (have not seen this myself) that a floating neutral can drift (due to static electricity) to hundreds of DC volts. It has almost no energy and is not dangerous but it could destroy you laptop or TV when you plug it in as the static charge is discharged.
* Of course use the correct size fuses and breakers.
* Be smart about what you connect to AC or DC and if you ever do get that "tingling sensation" stop and find out what the heck is going on.

Ron
 

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* Floating neutrals or grounds are bad. They can mask serious problems, cause electrical noise and cause erratic operation of almost anything. I have heard (have not seen this myself) that a floating neutral can drift (due to static electricity) to hundreds of DC volts. It has almost no energy and is not dangerous but it could destroy you laptop or TV when you plug it in as the static charge is discharged.
* Of course use the correct size fuses and breakers.
* Be smart about what you connect to AC or DC and if you ever do get that "tingling sensation" stop and find out what the heck is going on.

Ron
On the campground side of shorepower I have saw over 100 amps on the neutral when people have their camper plugs wired wrong. Hot and neutral wires reversed. (We are a private campground for long term campers and we use non-standard plugs.)
 
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