Connecting IN and OUT neutrals on voltronic AIO. Safe or wrong?

[Bitbin]

Hi. Got a question about connecting the ACIN AND ACOUT neutrals as they are not connected when in solar or battery mode (sbu). I Only use utility mode when cloudy. I have them connected right now but want to make sure its safe. The reason they are connected is because of a tankless electrical water heater that has the hot line connected to the utility directly but the neutral line is connected to the rest of the home so that when the inverter is ON it takes the neutral from the inverter and when its off it takes its neutral from the grid. By connecting the INPUT and OUTPUT neutrals the water heater has the neutral and hot lines connected to the grid all the time even if the inverter is on.

So is it wrong having the inverter and grid neutrals both connected together while their hot lines are seperated or is it no problem? Why i want them connected is so that the electric water heater can work without me switching over to grid as it alredy has the hot line connected to grid and now because the inverter and grid neutrals are connected it works without switching.

Im on a 230v grid and it has been working for now but wanted confirmation from someone who knows better that its safe.

 

[Mattb4]

Sounds like your AIO bonds NG when operating as inverter supply to AC out. If this is the case than jumpering the two neutrals could create 2 NG bonds in your electrical system when operating in AC bypass. This may or may not be an issue depending on how your utility grid in Turkey is setup. Someone from your neck of the woods would need to chime in.

 

[Bitbin]

Sounds like your AIO bonds NG when operating as inverter supply to AC out. If this is the case than jumpering the two neutrals could create 2 NG bonds in your electrical system when operating in AC bypass. This may or may not be an issue depending on how your utility grid in Turkey is setup. Someone from your neck of the woods would need to chime in.

What issues may come up if there are 2 NG bonds? And if there isnt 2 NG bonds is it safe?
My home isnt NG bonded but may be at the transformer. I have a ground rod connected to my inverter at the INPUT which is also connected to my fridge and AC ONLY.

 

[LydMekk]

I like to keep mine separate and not mix N in and out.
But that's me...

 

[RCinFLA]

Most of the Chinese inverters have a relay that connects neutral output to case ground when there is no AC input. When there is AC input it releases neutral connection from case ground and expects external AC input connections to provide neutral-ground bonding.

Most of the Chinese LF inverters provide no AC input neutral connection. This is due to their split phase, 240/120vac output transformer center tapped neutral output which will attempt to balance any AC input split phase, L1-N to L2-N 120 vac imbalance. This can cause excessive current through output transformer and damage inverter. These inverters should NOT be connected to split phase 240/120vac AC grid input.

 

[timselectric]

There are two reasons for connecting the input and output neutrals together.
1. If you need to carry the N/G bond through.
2. If have an autotransformer connected to the grid. (In bypass mode)
Otherwise, it's not recommended.

 

[timselectric]

The reason they are connected is because of a tankless electrical water heater that has the hot line connected to the utility directly but the neutral line is connected to the rest of the home so that when the inverter is ON it takes the neutral from the inverter and when its off it takes its neutral from the grid.

This wiring should be corrected.
Hot and neutral should be ran together to the same source.

 

[Pierre]

Most of the Chinese inverters have a relay that connects neutral output to case ground when there is no AC input. When there is AC input it releases neutral connection from case ground and expects external AC input connections to provide neutral-ground bonding.

Most of the Chinese LF inverters provide no AC input neutral connection. This is due to their split phase, 240/120vac output transformer center tapped neutral output which will attempt to balance any AC input split phase, L1-N to L2-N 120 vac imbalance. This can cause excessive current through output transformer and damage inverter. These inverters should NOT be connected to split phase 240/120vac AC grid input.

I am so glad we do not have to deal with this split phase malarkey. 230v 50Hz 1phase rules.

 

[Bitbin]

This wiring should be corrected.
Hot and neutral should be ran together to the same source.

Yea IK. I should just change how the lines go in The house instead of risking it. Thanks guys.

 

[timselectric]

I am so glad we do not have to deal with this split phase malarkey. 230v 50Hz 1phase rules.

It's not a split-phase issue. It's a N/G bond issue.
You all have a N/G bond, too.
You just don't have to deal with it much, because the grid does it for you.
Unless you are building a completely off grid system.

 

[Pierre]

It's not a split-phase issue. It's a N/G bond issue.
You all have a N/G bond, too.
You just don't have to deal with it much, because the grid does it for you.
Unless you are building a completely off grid system.

General comment , tongue in cheek ?

 

[Bitbin]

There are two reasons for connecting the input and output neutrals together.
1. If you need to carry the N/G bond through.
2. If have an autotransformer connected to the grid. (In bypass mode)
Otherwise, it's not recommended.

So just to make sure. If i dont have a NG bond in my home/inverter then i can connect the two neutrals even if they are different voltages as thr grid voltage fluctuates between 220-240v?

And how does one check for NG bond? My inverter is grounded to a copper rod in my garden. Does this count as NG bond?

 

[timselectric]

And how does one check for NG bond? My inverter is grounded to a copper rod in my garden. Does this count as NG bond?

Measure voltage from L to N, and L to G.
If the readings are the same, you have a N/G bond.
The electrical ground is created by the N/G bond.
A rod stuck in the earth is just a connection to earth.
That rod is not grounded, unless it's connected to the grounding system.

 

[Bitbin]

Measure voltage from L to N, and L to G.
If the readings are the same, you have a N/G bond.
The electrical ground is created by the N/G bond.
A rod stuck in the earth is just a connection to earth.
That rod is not grounded, unless it's connected to the grounding system.

Thank you!

 

[webbbn]

Are there any simple circuit diagrams of standard inverter configurations that could be referenced when these types of question come up? Having a diagram that shows, not only that you shouldn't do this, but why you shouldn't do this would go a long way in increasing understanding IMO. The more complex cases, like the active circuits in parallel inverters would be more difficult to describe in a simple figure, but, IMO, the answer in that case is, just follow the manual.

 

[Piet_de _Pad]

I raised a similar question in this post,
My conclusion is it's not a problem as long as you remove the inside NG bond in the inverter, which is active during bypass mode. If you don't you have two NG bonding in your network and that may result in leak currents that run over equipments not having any faults at all.
The external neutral switching relay I have in the post i mentioned I have eliminated by using a switch instead of an interrupter for the neutral in the Main switch panel. You don't even have to connect the Grid-Gnd and Grid-neutral to the AC. it's even better not to do that because you prevent a ground loop with it. Below a schematic I plan to use to back up a house.
I hope this helps