Inverter Installed - Open Ground?

[SpeakEasy]

I finished installing my new Victron 250w 12v inverter. I hard-wired it with direct connections to + and - battery terminals using 9 feet of 8AWG wire. There is a connection point on the inverter for a ground wire. The manual tells me that the "AC outlet is isolated from the DC input and the chassis." (They mean the inverter's chassis, not the trailer.)

My circuit tester registered the AC output as "open ground."

I tried running a ground wire from the inverter's ground connection to the trailer frame, believing the trailer frame to be the ground in this case. The circuit tester still registers "open ground."

First question - is any of this a concern?

Second question - why is it still registering "open ground"?

Third question - if I do need to ground it, how do I do so?

Thanks in advance.

-Speak

[naturist]

Agreed, not a concern.

IN THEORY, and if you really want to "play by the rules" and insure absolute perfection, you should bond the neutral to the ground and then drive an 8 foot grounding rod into the dirt beside your rig, attaching it to both the RV chassis AND the inverter ground pin with a huge honkin' bare copper wire, I think 6 gauge is required, but I'd have to look that up to be sure. Not exactly the most portable setup, to be sure, so . . . .

Good thing it's not a concern, eh?

[BFL13]

Checked the inverters now in our RV.

2000w PSW (PowerMax brand) showing its green no-fault lamp, tester shows two yellows, meaning "correct".

300w MSW (Can Tire-don't know supplier brand) shows all three lights on tester. (same as with previous MSW inverters) Tester does not have a code for what all three lights on means.

EDIT--no chassis ground connected on either inverter

[MrWizard]

No..NOT a concern

Tester show open ground, because neutral side of circuit is Not bonded to ground like utility power is, everything will work just fine, you would get the same tester response using a portable generator to power the RV

[2oldman]

Not a problem.

[SpeakEasy]

Bobbo wrote:


In the quote from the manual, the phrase "one of the AC output wires must be connected to the chassis" is what I am calling "bonding". That phrase in the manual implies that it is perfectly fine to go ahead and bond the inverter if it makes you feel better. There will be no actual benefit from doing so, but your tester will show what you want it to. If you do this, just be sure you bond the NEUTRAL wire to the chassis, otherwise, your tester will show the outlet as reverse polarity.

Understood.

Thanks again.

-Speak

[Bobbo]

SpeakEasy wrote:
"Local regulations my require a true neutral. In this case one of the AC output wires must be connected to the chassis, and the chassis must be connected to a reliable ground. Please note that a true neutral is needed to ensure correct operation of an earth leakage circuit breaker."

Not a problem. I like helping people solve problems. I like, even more, telling people they don't HAVE a problem.

In the quote from the manual, the phrase "one of the AC output wires must be connected to the chassis" is what I am calling "bonding". That phrase in the manual implies that it is perfectly fine to go ahead and bond the inverter if it makes you feel better. There will be no actual benefit from doing so, but your tester will show what you want it to. If you do this, just be sure you bond the NEUTRAL wire to the chassis, otherwise, your tester will show the outlet as reverse polarity.

[SpeakEasy]

Bobbo wrote:
It is showing OPEN GROUND because there is electrical potential between the inverter's outlet GROUND pin and its "NEUTRAL" pin. The only way to get this to not show OPEN GROUND is to connect the inverter's NEUTRAL pin to its GROUND pin. The same thing happens with a lot of the inverter generators. We build a "bonding plug" and plug it into an outlet on the generator that fixes that.

This is NOT of concern. This is not power from the utility company. The inverter, like the inverter generators, has a floating NEUTRAL and does not need to have its GROUND pin connected. Read some of the threads on this topic concerning the inverter generators. There are a lot of them. There is disagreement on whether to bond the generators with good arguments on both sides. (The only good argument on the side of bonding the generator is because some EMS units won't let power in if you don't.)

My advice is to contact the manufacturer, merely for your peace of mind, then stop testing the outlet. It is fine.

WARNING: I do not know if bonding is safe with your inverter. I do not know if bonding should be done with your inverter. I am providing this information only so you know what is causing that error message.

Thank you. Your explanation not only makes sense, but it helps me understand the following statement in the manual: "Local regulations may require a true neutral. In this case one of the AC output wires must be connected to the chassis, and the chassis must be connected to a reliable ground. Please note that a true neutral is needed to ensure correct operation of an earth leakage circuit breaker."

-Speak

[Bobbo]

It is showing OPEN GROUND because there is electrical potential between the inverter's outlet GROUND pin and its "NEUTRAL" pin. The only way to get this to not show OPEN GROUND is to connect the inverter's NEUTRAL pin to its GROUND pin. The same thing happens with a lot of the inverter generators. We build a "bonding plug" and plug it into an outlet on the generator that fixes that.

This is NOT of concern. This is not power from the utility company. The inverter, like the inverter generators, has a floating NEUTRAL and does not need to have its GROUND pin connected. Read some of the threads on this topic concerning the inverter generators. There are a lot of them. There is disagreement on whether to bond the generators with good arguments on both sides. (The only good argument on the side of bonding the generator is because some EMS units won't let power in if you don't.)

My advice is to contact the manufacturer, merely for your peace of mind, then stop testing the outlet. It is fine.

WARNING: I do not know if bonding is safe with your inverter. I do not know if bonding should be done with your inverter. I am providing this information only so you know what is causing that error message.

[RoyB]

I use a 600WATT AIMS PURE SINE WAVE Power Inverter feeding a couple of 120VAC Drop cords with multitap heads that is always ON.

Where it is tied to 12VDC the -12VDC connection is grounded to frame ground. i.e. the -12VDC lead feeding the 600WATT Power Inverter is at frame ground...

I never have had any issues.... Always have 120VAC at the two locations of the multi head extendion units that is plugged into the 600WATT AIMS Power Inverter...


google image

I also have never checked for open ground haha...

This is a drawing of my off-road floor plan..


Roy's image


Roy Ken

[rrupert]

You should contact Vectron and ask them.

[larry_cad]

First question - is any of this a concern?

YES

Second question - why is it still registering "open ground"?

Taken at face value, assume it is because there is still an open ground, from the outlet to the inverter chassis

Third question - if I do need to ground it, how do I do so?

Assuming the outlet is fed directly from the inverter with appropriate wiring type such as romex, it is likely there is a ground wire in the romex. Insure the ground wire is attached at both ends, the outlet at one end and the inverter chassis at the other end.

[BFL13]

I had a 1000w PSW inverter that showed one light for open ground. My MSW inverters showed all three lights. I will check the inverters we have now later.

My Vector inverter's manual says the chassis ground from lug to trailer frame is just to reduce radio and television interference. Deck mount converters also come with lugs on their chassis,