Multiplus II with voltage on AC output ground

[stumped]

I am installing a multiplus II and am noting that when the ground relay is disabled in victron connect that there is still voltage present on the output ground when inverting from 48V battery. I have not connected AC input yet. My understanding is ground should be isolated from neutral when the relay is disabled (open state). But on this unit, it does not seem that is, at least not fully. Chassis ground is not connected to anything currently. Voltage measurements below with and without the relay enabled.

With relay enabled:
Ground to Line = 120V
Ground to Neutral = 0V

With relay disabled:
Ground to Line = ~70V
Ground to Neutral = ~`50V
(interesting that these two measurements added are ~120V)

Voltage between Line and Neutral on AC out is 119V and the inverter seems to power appliances fine when relay is closed. I have not tried when the relay is open. My concern is the voltages measured on ground with the relay open as I want to connect the inverter AC output to an Interlocked mains panel with grid off where the neutral/ground bonding already exists.

Are the voltages found on ground normal with the multiplus?

 

[sunshine_eggo]

I am installing a multiplus II and am noting that when the ground relay is disabled in victron connect that there is still voltage present on the output ground when inverting from 48V battery. I have not connected AC input yet. My understanding is ground should be isolated from neutral when the relay is disabled (open state). But on this unit, it does not seem that is, at least not fully. Chassis ground is not connected to anything currently. Voltage measurements below with and without the relay enabled.

With relay enabled:
Ground to Line = 120V
Ground to Neutral = 0V

With relay disabled:
Ground to Line = ~70V
Ground to Neutral = ~`50V
(interesting that these two measurements added are ~120V)

Voltage between Line and Neutral on AC out is 119V and the inverter seems to power appliances fine when relay is closed. I have not tried when the relay is open. My concern is the voltages measured on ground with the relay open as I want to connect the inverter AC output to an Interlocked mains panel with grid off where the neutral/ground bonding already exists.

Are the voltages found on ground normal with the multiplus?

You have confirmed a floating ground, i.e., N and G are not bonded.

This is normal and typical.

It's irregular to decouple the N-G bond without a specific reason. Why did you do so?

 

[stumped]

I have since connected the multiplus chassis ground and the DC negative bus bar to the ground in my mains service panel with grid turned off. This should have provided a ground reference that the house uses yet the readings on the AC output of the multiplus are the same. Would the multiplus AC out neutral need to be connected in the same panel where the bonding exists before the ground no longer floats?

I want to use the inverter only when there is no grid power and leverage the mains panel distribution network to power various loads connected there with the inverter. Plan was to disable the bonding in the multiplus then connect the AC output to the mains panel where the bonding already exists.

 

[sunshine_eggo]

Gotcha.

If N-G bonded at panel, then bonding relay open.

Victron L-N-G out to panel.

 

[stumped]

Thanks @sunshine_eggo . I juest checked my unbonded gas generator and it does the same thing.

 

[sunshine_eggo]

Yep. I ran "floating" for longer than I care to admit. N-G bond was fine. G to earth was nonexistent. Was 50V potential to the earthed shipping container. I completely spaced on bonding G to the container/earth.