Option to bypass inverter - Transfer switch?

Hedges said:

It is not important when grid input to inverter is shut off. You can leave grid feeding input of inverter.

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Maybe it's not a danger but I am not comfortable working on the Inverter with any power coming into the inverter. So I want to switch off the input to the inverter. Please see my above proposed design.

No, "Breaker here" is the breaker which must be interlocked to the breaker between "grid" and "loads panel".
You still have grid and inverter output potentially fighting, if you don't switch "breaker here" in the correct order.

The breaker between "grid" and "inverter" does not need to be interlocked.

What are the 3 wires? L1, L2, N?
Here in the US, we do not switch N, except in mobile applications where in addition to disconnecting N from shore power, we also bond N to a ground wire.

How is ground handled?

kolek said:

Maybe it's not a danger but I am not comfortable working on the Inverter with any power coming into the inverter. So I want to switch off the input to the inverter.

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I agree.
But do so manually, separately. It isn't the one that has to be interlocked with the others.

Lock Out Tag Out is taught at work for safety.

Hedges said:

No, "Breaker here" is the breaker which must be interlocked to the breaker between "grid" and "loads panel".
You still have grid and inverter output potentially fighting, if you don't switch "breaker here" in the correct order.

The breaker between "grid" and "inverter" does not need to be interlocked.

What are the 3 wires? L1, L2, N?
Here in the US, we do not switch N, except in mobile applications where in addition to disconnecting N from shore power, we also bond N to a ground wire.

How is ground handled?



I agree.
But do so manually, separately. It isn't the one that has to be interlocked with the others.

Lock Out Tag Out is taught at work for safety.

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>What are the 3 wires? L1, L2, N?
Yes

>How is ground handled?
I don't understand the question.

>No, "Breaker here" is the breaker which must be interlocked to the breaker between "grid" and "loads panel".
Okay I'll try to think again and redesign it.

Ok @Hedges @Mattb4 @meetyg How does this look to you?
Mattb4 I think this matches essentially the diagram you posted.

Next, make sure you get the following correct:

1) Are you supposed to switch neutral? Is neutral supposed to be bonded to ground somewhere?
When you use transfer switch to feed loads from inverter, and you turn of other breaker feeding inverter, neutral is floating.

2) Your panel has grid --> main breaker --> RCD --> other breakers.
Should you have RCD --> inverter?
Or is it OK to have grid --> inverter?
It may be that due to your grid type ("TT", "TN", ... many types), it needs RCD before anything in the house, for safety.

3) Is "ground" a thing in Japan, does it go to sockets and hardwired equipment?

kolek said:

>How is ground handled?
I don't understand the question.

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Is there a wire from chassis of equipment to a ground rod or water pipes, so chassis is never higher voltage than earth (shock hazard)?
Are outlets 2 wire L/N or 3 wire L1/N/L2? Or 3 wire L/N/G or 4 wire L1/N/L2/G?

Hedges said:

Next, make sure you get the following correct:

1) Are you supposed to switch neutral? Is neutral supposed to be bonded to ground somewhere?
When you use transfer switch to feed loads from inverter, and you turn of other breaker feeding inverter, neutral is floating.

2) Your panel has grid --> main breaker --> RCD --> other breakers.
Should you have RCD --> inverter?
Or is it OK to have grid --> inverter?
It may be that due to your grid type ("TT", "TN", ... many types), it needs RCD before anything in the house, for safety.

3) Is "ground" a thing in Japan, does it go to sockets and hardwired equipment?

Click to expand...

>1) Are you supposed to switch neutral? Is neutral supposed to be bonded to ground somewhere?
If you check the pictures I sent you of my panel, neutral is being switched by both the main breaker and RCD in my panel. I had assumed it got switched. There is no physical copper pole in the ground at the house here as far as I know. I have no idea what neutral is connected to other than the utility pole.

>2) Your panel has grid --> main breaker --> RCD --> other breakers.
Yes, I understand that. Regarding the RCD, I don't know how to get between the RCD and the 20A breakers in order to pick up the output from the RCD. You can probably see in the picture I sent but it's like they are connected in the panel and there is no room in the panel to move anything or add anything. I'd have to buy a new RCD. I don't think we need a RCD but I am not 100% sure. I asked @Daddy Tanuki if he has one (he's also in Japan) and he said he doesn't. I can do a little more research if you think I should. Or I could just get one and install it before the inverter input to be extra safe. It's not a big deal to add one and they aren't very expensive.

> 3) Is "ground" a thing in Japan, does it go to sockets and hardwired equipment?
Meaning what exactly? Grounding at the panel? Grounding outside the house somewhere? Ground as in a copper pole in the ground? Ground as in the neutral wire that goes back to the utility pole? I really don't know how these things work here. I can tell you that regular home AC outlets don't have 3 prong plugs in Japan, it's like the old style 2 prong in North America before they added the 3rd grounding prong.

I'd love to say I have an expert electrician here helping me but I don't. I don't even know an electrician. The only "electrician" close by is an old dude who's like 85 years old, I can't rely on him to keep an appointment or come out to my place, and he seems to have even less expertise than I do. For example, discussing "Neutral" or "ground" with an electrician here would be a challenge because I don't really understand them that well even in English, and I don't know the words for these terms in Japanese.

Edit: I did some research on RCD... it's standard in Japanese homes and covers the whole house.

It may be that your neutral from grid is grounded to earth by the grid. And entire house gets disconnected from L1/N/L2 by RCD if > 30 mA flows from your equipment back to the earth, e.g. through water or gas pipes.

When you disconnect from grid and power house from inverter, everything is floating, isolated. You need to find what should be done.

In the US, neutral from grid bonds to ground at the meter and the first disconnect. A ground wire from there goes to a ground rod and all pipes, also to chassis of equipment and a ground pin of outlets. At water heater, cold, hot, and gas are bonded together with a wire.

For kitchen, bath, garage, outside, in the US we have GFCI outlets or breakers with disconnect if > 5 mA flows back through earth or pipes (current in L & N are measured as different), for human safety.

Hedges said:

Is there a wire from chassis of equipment to a ground rod or water pipes, so chassis is never higher voltage than earth (shock hazard)?
Are outlets 2 wire L/N or 3 wire L1/N/L2? Or 3 wire L/N/G or 4 wire L1/N/L2/G?

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I'm 90% sure there is no physical ground or ground rod or connection to water pipes at this house.
3 wire L1 N L2
@Daddy Tanuki can you agree I have this right?

@Daddy Tanuki @Hedges

>It may be that your neutral from grid is grounded to earth by the grid. And entire house gets disconnected from L1/N/L2 by RCD if > 30 mA flows from your equipment back to the earth, e.g. through water or gas pipes.
Yes I'm 90% sure that's how it works.

>When you disconnect from grid and power house from inverter, everything is floating, isolated. You need to find what should be done
When I switch the breaker off on the house now and there's no power, it's floating, meaning no neutral bond. Does it matter? If electricity is off, why do I need a neutral bond connection? And when I power the house from the inverter, the inverter will be connected to neutral and be delivering neutral to my panel. Isn't that what we want? I don't understand your concern here.

If your point is that I need to find out if I need to physically drive a copper pole into the ground and connect my neutral to that in order to modernize and make this old house more safe electrically, then yes, I'm not sure and I can check into it. The US is far more sophisticated and strict when it comes to this, things are primitive in old houses here, I mean the houses 1 generation older than the one I'm living in had walls made of mud and bamboo.

When fed from grid, I think N from grid is grounded somewhere.
When running off-grid, your system including L1/N/L2 is isolated. Maybe OK, maybe not, try to find out how things are done there. Ignoring any PV, this is a UPS, which must be common.

If we have an RV, we bond N to chassis of the RV, and equipment is grounded to chassis.

What has been a problem for some is that PV +/- inputs of cheap inverters sometimes carry common mode AC. When PV panels are mounted and their frames have a path to earth (e.g. ground mount or on cargo container), chassis of RV was driven with AC voltage, causing shocks for man and beast. Solution was a ground wire bonding PV frames to inverter.

You may have similar issues. If it was me I would bond all chassis together and to ground rod and/or pipes. But then I'm familiar (too familiar) with shock hazards in the US.
You need to find out what is used for similar setups in your location.

@Hedges
Thank you for sticking with me. It's starting to become a lot more clear.

At least for now, I'm not planning on going offgrid and disconnecting from grid.
I'll get to your recommendation in my next message, first I want to be clear about this:

You wrote:
>When fed from grid, I think N from grid is grounded somewhere.
>When running off-grid, your system including L1/N/L2 is isolated.

You're saying, when my battery is dead and I'm pulling from grid, that gives me a neutral bond which is grounded, so I'm safe.
But when I'm pulling from battery, I'm floating and no longer have the protection of the neutral though my inverter to grid?
Is that what you're saying?

I thought because my inverter was always connected to neutral, I was safe even when running from batteries.

Yes, that's what I'm saying.
Your drawing shows a 3-pole breaker, one pole disconnecting its neutral from the grid.
Which may be required in your location, because with ground bond at an unknown distant location, Neutral can become hot.
That's why you need to find out how to make a UPS type setup safe with your kind of grid.

The RCD does something, if there is leakage current through earth it disconnects all wires between grid and your appliances.
That's why I think there should be an RCD between grid and your inverter. (maybe pulling wires from output of existing RCD, have it feed transfer switch and inverter? Maybe you also should have RCD between inverter and loads?)

Having everything floating when running from inverter may or may not be safe. It seems safe, until one fault occurs, and a second fault could shock someone. Find out what is proper in your area.

@Hedges
Ok was not aware that running from battery essentially isolated me from neutral.

>Which may be required in your location, because with ground bond at an unknown distant location, Neutral can become hot.
I will find out in more detail about how neutral is bonded here in Japan. Really appreciate you bringing that to my attention.

>Maybe you also should have RCD between inverter and loads?
> Find out what is proper in your area.

Yep I'll research that and also discuss with @Daddy Tanuki.

Massive thanks to you, you've added a lot more clarity to this!!

Going back to your previous point, you said:
"If it was me I would bond all chassis together and to ground rod and/or pipes. But then I'm familiar (too familiar) with shock hazards in the US."

I'll consult with a local electrician but is there any harm in just following this advice anyway?

I think bonding all exposed metal together and to ground rod is almost always a good idea.

There may be exceptions when a utility line worker is in a bucket truck touching power lines, don't want metal in the bucket grounded.
Hospital and wires inside patients, they do things in a special way.
Would not want a fault to electrify chassis and water pipes, while a guy in the shower touches the drain pipe that also reaches earth but isn't bonded to the others. (first few deaths during Desert Storm were electrocutions in the shower.)

Hedges said:

I think bonding all exposed metal together and to ground rod is almost always a good idea.

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Very helpful to understand this. Thank you so much @Hedges !

kolek said:

@Hedges
Ok was not aware that running from battery essentially isolated me from neutral.

>Which may be required in your location, because with ground bond at an unknown distant location, Neutral can become hot.
I will find out in more detail about how neutral is bonded here in Japan. Really appreciate you bringing that to my attention.

>Maybe you also should have RCD between inverter and loads?
> Find out what is proper in your area.

Yep I'll research that and also discuss with @Daddy Tanuki.

Massive thanks to you, you've added a lot more clarity to this!!

Going back to your previous point, you said:
"If it was me I would bond all chassis together and to ground rod and/or pipes. But then I'm familiar (too familiar) with shock hazards in the US."

I'll consult with a local electrician but is there any harm in just following this advice anyway?

Click to expand...

My cabin was two wire with no ground at, as such I use my inverters neutral to ground bound and tied all gear + shop to it. House itself still has no ground as the wiring was never set up that way and I am not stripping the interior out to run new wiring. Still deciding how to approach this myself

Daddy Tanuki said:

My cabin was two wire with no ground at, as such I use my inverters neutral to ground bound and tied all gear + shop to it. House itself still has no ground as the wiring was never set up that way and I am not stripping the interior out to run new wiring. Still deciding how to approach this myself

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@Hedges
Looks like I'm not the only one in Japan living with primitive electrical wiring!

I run my inverter output to these Connecticut Electric Manual transfer switches, then I can put what I want on solar or utilities

@Lighthouse Beacon
Wow. Is that DIY? So cool.
Includes "Outdoor waterfall"
Geez. Can I move to your house?
You just need to relabel one of those to say "K's room" lol