Eg4 3000 no ground when inverting

[Cardude]

I have an eg4 3000 inverter on a hand truck with one 48v battery I’m using temporarily while building a stepvan. Awhile ago while using a power tool I got a shock, so a member told me to ground the case of inverter to the chassis, which I did.

Today when testing the 120v output plug of the inverter when it’s inverting (not passing thru) I get 80v from neutral to ground, and 46v from hot to ground. From what I understand reading other threads the inverter is not bonding internally to ground like it should.

Is the wire from the case to the chassis enough, or do I need to do a jumper wire also? Like do the jumper wire trick at the shore power input maybe? I was eventually going to install a shore power cord.

Edit:
I forgot, I’m also getting some strange surging happening on a fan installed. And the controller for the fan doesn’t work well like it did when plugged into the grid.

 

[meetyg]

Grounding to the hand truck has basically no effect.
So you have two issues here:
1. No real ground
2. No N-G bonding (floating Neutral)

Sometimes people do an N-G bond on mobile inverters, just so that some appliances will work (mainly EV chargers, which check the voltage between Ground and Neutral). But that's just fooling those appliances. No real benefit if you don't have real ground. On RVs I know that some ground to the chassis if the vehicle, but since I'm not an RV guy, I don't really understand how that helps.

What I like to do with mobile inverters, is to N-G bond (behind an RCD/GFCI), but also run a ground wire to a real ground. This could be the ground of a household socket, or if in the field, this could be to an earth rod inserted into moist soil/ground.

This way you will not have a floating Neutral (probably the cause of the weird fan behavior) but also added safety should a fault occur (RCD/GFCI will open if there is leakage outside of the circuit).

If you plan to connect grid (AC IN) to the inverter at some time, this N-G bond needs to be removed in order not to cause ground loops etc...

 

[Cardude]

Thanks for the reply!

I was not clear. The case of the inverter that is mounted on the hand truck is grounded to the chassis of the stepvan. I ran a grounding cable after getting shocked.

And yes, at times the step van will be connected using a shore power cord, which would give the truck a good ground. But it will mostly be used without being plugged into the grid, so I would like to get a good ground somehow when not plugged in.

 

[EG4_Jared]

I would check setting 8 and 9 to make sure that the output setting is 120v at 60hz (unless 50hz is needed). Also, would you be able to post pictures of the wiring and check to see if a neutral-ground bond is being made on the inverter?

 

[Cardude]

I would check setting 8 and 9 to make sure that the output setting is 120v at 60hz (unless 50hz is needed). Also, would you be able to post pictures of the wiring and check to see if a neutral-ground bond is being made on the inverter?

Yes it’s set to 60hz.

I’m not at the van currently. I have it wired as the manual states and did not do anything additional, other than running that ground wire from the inverter to the chassis of the van.

 

[Cardude]

Just to re-up this, I’m trying to figure out if I can use a neutral-ground jumper plug at the shore power input on my diy hand truck generator.

I currently have the case of the inverter connected to the chassis of the van, so just wanted to make sure that’s OK to keep along with using the plug.

I’m getting some strange voltage readings from the 120 output of the inverter. When testing the 120v output plug of the inverter when it’s inverting (not passing thru) I get 80v from neutral to ground, and 46v from hot to ground. I’m also getting some strange surging from a fan that’s plugged in, and I also have a fridge plugged in and don’t want to burn that up somehow with incorrect voltage. I was hoping the neutral-ground plug would clear this up?

The voltage from hot to neutral is 120v.

So to recap my concerns are this:

1. Will the case ground at the inverter to the chassis be ok in conjunction with a neutral-ground plug?
2. Will the odd voltages be cleared up by this neutral-ground plug?

I suppose I could just try the plug and do some testing, but I dont want to screw anything up!