Grounding confusion - 3300W pure sine inverter on Wooden frame in laundry

[new2renewing]

Hi all,

Please dumb it down for me as I have searched & searched, and read & read, and am even more confused about whether or not to ground my inverter.

Setup:

Max output required: 2450w through single power board and extension cable.
In Australia (240V AC).

Giandel 3300W/6600W pure sine inverter
3300W Giandel link
I have a resistor to pre-charge the inverter as it is over the recommended 1500-1700W for pre-charging.
1 (soon to be 3) parallel Renogy 1000AH 12V Lifepo4
2/0 wire + 300A battery to inverter fuse
20A solar coming in via renogy wanderer pwm (soon upgrading to 60A via tracer mppt)

I will be storing the inverter, batteries, and charge controller on this homebuilt frame:

Here is a photo of the grounding terminal:

The manual of the inverter mentions grounding in this paragraph:

I am planning to leave this in the laundry on ceramic tiles, with an extension cord running into the main house. Followed Will's basic build on a board for 1st setup, so this is my second build. He never mentioned anything about grounding.

My questions are:

1. Do I have to ground this system?
2. Is the inverter chassis itself "live" or any other way dangerous whilst being used from battery/solar?
3. Is the battery, or any of the wires, or the cables running from AC outlets dangerous (assuming no faults or exposed wires)?
4. Will the tiles or any part of the surrounding area be dangerous if grounded/not grounded?
5. Anecdotally, I didn't ground my 1000W inverter 1st system. Often touched it, obviously to turn inverter power on, or to move the wooden frame. My family also would brush past it whilst heading out the back. Was I putting my family at risk?

Sorry in advance if these questions are really simplistic & thanks in advance

 

[Hedges]

The chassis could become live depending on what the inverter output is wired to, in particular if it had a fault.
Usually a battery should not be driven to dangerous voltages by AC, but some non-isolated inverters have issues preventing us from wiring the AC terminals as we normally would in the U.S. (We ground the neutral wire at one point in our entire house wiring)

You ought to connect a wire from that grounding terminal to a ground stake (10' copper plated 5/8" steel rod) driven into the ground, also to metal water pipes.

Because it is a laundry area, you could be wet and could be standing on a wet floor. Grounding things ensures they are at the same potential as earth, reducing shock hazards.

A ground-fault extension cord, or a ground-fault outlet put in a box to make an extension cord, would be a good addition.
Here in the U.S., fixed GFCI installations only interrupt the hot connection, but portable GFCI interrupt the neutral as well because might be plugged into an outlet that was wired incorrectly.
A 2-pole GFCI would be best, but if single pole double check to make sure it is the hot which gets tripped (assuming hot and neutral are distinguished in Australia)

I survived for years with non-GFCI laundry hookups out in the rain. Electric dryers used to be wired funny, two hots (our 240V setup) but no neutral, the ground wire actually carrying current from the motor as well as being connected to chassis. An open circuit ground wire would make the chassis electrified (unless interrupting circuit turns off the appliance, which I think it does.)

I feel much more comfortable now that I've rewired the dryer with separate neutral and ground to 4-wire plug, installed a 2-pole 230V 30A GFCI breaker for the dryer, and 120V GFCI outlet for washer.

With all the electrical safety classes I've had to take at various jobs, and the descriptions of injury from electrical shock, I'm more careful than before.

 

[new2renewing]

The chassis could become live depending on what the inverter output is wired to, in particular if it had a fault.
Usually a battery should not be driven to dangerous voltages by AC, but some non-isolated inverters have issues preventing us from wiring the AC terminals as we normally would in the U.S. (We ground the neutral wire at one point in our entire house wiring)

You ought to connect a wire from that grounding terminal to a ground stake (10' copper plated 5/8" steel rod) driven into the ground, also to metal water pipes.

Because it is a laundry area, you could be wet and could be standing on a wet floor. Grounding things ensures they are at the same potential as earth, reducing shock hazards.

A ground-fault extension cord, or a ground-fault outlet put in a box to make an extension cord, would be a good addition.
Here in the U.S., fixed GFCI installations only interrupt the hot connection, but portable GFCI interrupt the neutral as well because might be plugged into an outlet that was wired incorrectly.
A 2-pole GFCI would be best, but if single pole double check to make sure it is the hot which gets tripped (assuming hot and neutral are distinguished in Australia)

I survived for years with non-GFCI laundry hookups out in the rain. Electric dryers used to be wired funny, two hots (our 240V setup) but no neutral, the ground wire actually carrying current from the motor as well as being connected to chassis. An open circuit ground wire would make the chassis electrified (unless interrupting circuit turns off the appliance, which I think it does.)

I feel much more comfortable now that I've rewired the dryer with separate neutral and ground to 4-wire plug, installed a 2-pole 230V 30A GFCI breaker for the dryer, and 120V GFCI outlet for washer.

With all the electrical safety classes I've had to take at various jobs, and the descriptions of injury from electrical shock, I'm more careful than before.

Thank you for the comprehensive response. I'm sorry if my understanding is overly simplistic, but reading other topics makes me realise I need a more basic approach.

The chassis could become live depending on what the inverter output is wired to, in particular if it had a fault.
Usually a battery should not be driven to dangerous voltages by AC, but some non-isolated inverters have issues preventing us from wiring the AC terminals as we normally would in the U.S. (We ground the neutral wire at one point in our entire house wiring)

How can I find out if my inverter is isolated? Is this how I work out whether to ground my system? The ac plugs can have 3 prongs in australia, but many of the appliances I'm using have two. Does this affect whether I need to ground it?

You ought to connect a wire from that grounding terminal to a ground stake (10' copper plated 5/8" steel rod) driven into the ground, also to metal water pipes.

If I have it in the main house, is this necessary/possible?

Because it is a laundry area, you could be wet and could be standing on a wet floor. Grounding things ensures they are at the same potential as earth, reducing shock hazards.

If I were to move the whole wooden apparatus (containing 12V battery, 12V inverter, charge controller & fuses) into the main house (wooden floorboards), would this remove my need to ground the system? I'm not completely set on having it in the laundry, it was just closest to the outside where I can set up my panels (400-600W of solar suitcases).

A ground-fault extension cord, or a ground-fault outlet put in a box to make an extension cord, would be a good addition.
Here in the U.S., fixed GFCI installations only interrupt the hot connection, but portable GFCI interrupt the neutral as well because might be plugged into an outlet that was wired incorrectly.
A 2-pole GFCI would be best, but if single pole double check to make sure it is the hot which gets tripped (assuming hot and neutral are distinguished in Australia)

This information seems valuable but I'm having difficulty understanding it. Does this mean that there is a device or a specific type of AC cord I can buy to avoid having to ground the system? How do I check whether single or double pole?

I survived for years with non-GFCI laundry hookups out in the rain. Electric dryers used to be wired funny, two hots (our 240V setup) but no neutral, the ground wire actually carrying current from the motor as well as being connected to chassis. An open circuit ground wire would make the chassis electrified (unless interrupting circuit turns off the appliance, which I think it does.)

That sounds dangeous, how could I avoid an open-circuit ground wire? As in my first post, I'm now aware of the possibility that somehow the wooden box contatining all of my equipment could become electrified somehow. Obviously it didn't happen with my ungrounded 1000W inverter, but considerin it's not really mentioned in all of the videos and beginner setups, it's hard to know exactly what to do as a beginner. Thanks for your time

 

[upnorthandpersonal]

In Australia, you use the MEN grounding system. You can't just put a ground stake in due to Australia having very dry (and unsuitable) sand to do this. Your place should be equipped with an earth bar, from which every protective earthing goes to sockets, light points, etc. - and that would be the place to

Now, keep in mind that with MEN, the earth and neutral are bonded together on the main switch board. The Protective Earth Neutral (PEN) comes from the grid as well, and this is all bonded together. You have to make absolutely sure this inverter can deal with that. You also have to make sure this is legal to do. If not, you're going to be in trouble. That said, I'm not a licensed electrician in Australia, so ask someone locally.

Don't start messing around with this on your own - you should make sure that what you're doing is correct, and that means talking to a local electrician who's worth the money you pay him.

 

[new2renewing]

In Australia, you use the MEN grounding system. You can't just put a ground stake in due to Australia having very dry (and unsuitable) sand to do this. Your place should be equipped with an earth bar, from which every protective earthing goes to sockets, light points, etc. - and that would be the place to

Now, keep in mind that with MEN, the earth and neutral are bonded together on the main switch board. The Protective Earth Neutral (PEN) comes from the grid as well, and this is all bonded together. You have to make absolutely sure this inverter can deal with that. You also have to make sure this is legal to do. If not, you're going to be in trouble. That said, I'm not a licensed electrician in Australia, so ask someone locally.

Don't start messing around with this on your own - you should make sure that what you're doing is correct, and that means talking to a local electrician who's worth the money you pay him.

Thank you for your reply.

In addition to my above questions, I'm actually more confused now. Why do no portable power stations (i.e. Jackery, Bluetti) have ground connections?

In all of the videos Will made, there was never any mention of grounding.

Does this mean that everyone in Australia who has built an off-grid battery+inverter system following these instructions is not safe? Is there a cutoff of inverter power where I need to consult an electrician? Is the wooden frame I have the setup on inherently unsafe? What protection is built into the inverter?

Reading many other forums geared to beginners, it very quickly devolves from building a beginner setup into something that requires an electrician's degree to understand. I came across this website after following links from other off grid inverter builds:

RVDsafe

Do I need to install something like this? Which one? Obviously if I can build my inverter + battery + solar setup, then buy a simple device and have an electrician install it for safety, I'll do this (no logic in spending $5k and then not being safe). Thanks for your assistance in advance.

 

[upnorthandpersonal]

I have several inverters that all have ground connections. Victron for example has a ground connection:

The question now becomes, do you bond this ground together with neutral, and if so, where? For example:

Green Pro Consulting is located in South Africa, and they use the TN-C-S ground system. You can see that, on the load side, neutral and ground are not bonded (the only bond is at the point of connection from the grid). In TN-S and TN-C, this is typically even further away and PE and Neutral are not connected except at the point of distribution. In all cases, the metal enclosure gets connected to the PE (earth).

Thus, what you need to do is entirely up to your local code, laws, and the earthing system in place.

 

[Factory400]

I would at least bond the neutral to the ground terminal to ensure that if a hot leg contacts the chassis - it will blow the circuit protection.

Actual Earth ground options certainly vary by geography.

 

[upnorthandpersonal]

I would at least bond the neutral to the ground terminal to ensure that if a hot leg contacts the chassis - it will blow the circuit protection.

No, don't. If he has an MEN system (and he's in Australia, so I'm pretty sure he does) you can't just make these connections anywhere. The 'MEN Link' has to be done with a specific wire thickness and at a specific location. It's also not a good idea to generalize this, since it depends completely on grounding system, code and local laws. Take TT for example, where an RCD is mandatory but Neutral and Earth are never connected together. Bonding Neutral and Earth is only for those systems where the circuit protection will blow in case an live wire comes into contact with e.g. a metal case. If you do this in multiple/wrong locations you can actually bypass this protection altogether.

OP needs to get an electrician involved.

 

[new2renewing]

Thank you for all of your considerate replies. I feel like I'm way out of my depth, but this is the beginner's section.

I don't understand most of the terminology presented, and don't really understand the answers, except to get an electrician, which I'm happy to do if I'm unable to understand the basics. Have the questions in my previous posts been worded incorrectly?

In the inverter site, it has the following information:

Is this lying & there is really no protection at all?

Where is the absolute beginner's section for those who are following Will's videos?

@Will Prowse , we have not spoken but I would really appreciate if you could assist in some of the questions in my previous posts.

I have bought the recommended inverter, charge controller, battery and wiring from your Mobile Solarpower site, and have followed your videos carefully for the first system, now with the larger inverter I'm extremely confused about grounding the system & all the acronyms that are never discussed. Will an RCD protect me? Are the Giandel inverters dangerous? What is a GCFI & do I have one? Do I connect the battery negative to the ground? Do I have to hire an electrician to make my portable wooden setup safe? Thank you

 

[sunshine]

I feel like I'm way out of my depth, but this is the beginner's section.

1) A wire from that specified earth terminal to a earth point- NOT to the copper water water pipes and preferably to its own earth stake.
Do this before going live!

 

[jasonhc73]

 

[Hedges]

When you mentioned "laundry", I though you were powering the washing machine with this.
If you use it indoors, dry location (not powering kitchen appliances), the grounding issue isn't as big a deal.
Do you have house wiring, with a grounded outlet? Can use a ground wire to that.

2-wire appliances are common. If plastic, nothing to get a shock from. Our old TV sets had 2-wire plug and chassis tied to one pin, so those could be plugged in backwards and would give a shock. A metal appliance or lamp with 2-wire cord could be a shock hazard if it had a fault inside and you were touching something else grounded.

Something like those RVDsafe are the thing to use if you will be exposed to wet location, like out of doors, bathroom, kitchen. "GFCI" is U.S. code requirement for those locations. The U.S. version detects if > 0.005A that goes out one wire doesn't come back in the other (might be going through you), and shuts off within 0.016 seconds. These days they are part of the plug or power cord for hair dryers and pressure washers.

 

[new2renewing]

When you mentioned "laundry", I though you were powering the washing machine with this.
If you use it indoors, dry location (not powering kitchen appliances), the grounding issue isn't as big a deal.
Do you have house wiring, with a grounded outlet? Can use a ground wire to that.

2-wire appliances are common. If plastic, nothing to get a shock from. Our old TV sets had 2-wire plug and chassis tied to one pin, so those could be plugged in backwards and would give a shock. A metal appliance or lamp with 2-wire cord could be a shock hazard if it had a fault inside and you were touching something else grounded.

Something like those RVDsafe are the thing to use if you will be exposed to wet location, like out of doors, bathroom, kitchen. "GFCI" is U.S. code requirement for those locations. The U.S. version detects if > 0.005A that goes out one wire doesn't come back in the other (might be going through you), and shuts off within 0.016 seconds. These days they are part of the plug or power cord for hair dryers and pressure washers.

In my thread about the 1000W setup, @snoobler suggested I didn't need to ground it, but the 3300W version is scary & big, hence my current topic. It makes me wonder if the need to ground is based on size? But apparently not?

Thank you for your response again. Perhaps an Australian-ism has lead to confusion over whether or not I should ground this system!


When I say laundry, I mean it is stored in the same area as the washing machine and dryer, which is simply another room in the main house - the atmosphere in there doesn't really get too humid, however I'm also happy to move it into the main house (shared kitchen/dining with wooden floors) if this would prevent a need for grounding with the lead.

I was also planning on mostly enclosing the top and sides of the whole setup (inverter, charge controller, battery, fuse) to protect from any moisture that settled. Beforehand if it was humid, I just covered it in a dry towel. Perhaps this was a stupid thing to do?


To answer your question, yes, there is house wiring. I assume all of the outlets are grounded, it is to code and obviously has a fusebox. Is there a certain cable or device I buy to plug into the inverter AC outlet, and then into one of these outlets? Is that what you mean? I have taken a photo of the outlets that I have, along with a typical plug (this one is for the hairdryer, both the plugs on the inverter look like this too, in AUS it is impossible to plug in anything in reverse. Some plugs, like the PC, have a third prong, the vertical one at the bottom):

The appliances I was planning to use are the following:

Sub/Amp/Stereo combo with Playstation and 55" flat screen for the family - 480W
PC and 2 x Studio monitors (1100W startup spike, 430-600W typical)
Lights (100W worth of LED lights)
Soldering iron - 450W
Air purifier - 140W

Occasional use, never at the same time:
Vacuum cleaner - 2450W peak, 1800W operation
Microwave - 1300W peak, 1000W operation
Kettle- 2000W operation
Heat gun - 1900W

Only if house power is down
Chest Freezer - rated at 279kWh per year, which I guess means it uses around 800Wh per day or less?
Fridge - 250W

I was planning to plug these into an extension cord from the inverter which is then connected to a surge-protected power board, which runs into the main house. It shouldn't get too humid in here - this is how I ran the previous ungrounded 1000W inverter. Is this the right thing to do?

Hope this gives more information, sorry if my questions are overly simple, excited to get to the bottom of this.

 

[upnorthandpersonal]

1) A wire from that specified earth terminal to a earth point- NOT to the copper water water pipes and preferably to its own earth stake.
Do this before going live!

No, No, No. This is not correct. Not in Australia. OP, since this is the beginner section and based on what you write: you're out of your depth. People are replying with things that are only relevant in e.g. the States without taking into consideration that the Australia (and the rest of the world) use different earthing systems. There is also a difference between what people (especially in the States and Canada) consider 'grounding' and the what the rest of the world understands (difference between 'grounding' and 'earthing'). Mike Holt also is specifically talking from an NEC electric code and the US kind of grounding.

For everyone else: in most of the world, you don't bond the neutral to the earth, and if you do - there are very specific requirements (such as only doing this in one specific place with a specified wire, like in the MEN system in Australia). You don't just ram a rod in the ground (this does not work in Australia!). You don't just start connecting to copper pipes, you don't just put a bridge to neutral from earth.

@new2renewing : the protections listed on the inverted sheet you posted have nothing to do with the electrical safety when installed in the building and protection of persons, they are regarding protecting the inverter. The RCD requirements and others in your code/laws are for protections of persons, and should be strictly followed. Do not follow the advice posted here, it's wrong and dangerous. Get a local electrician.

 

[new2renewing]

I'm so confused.

Perhaps it's best to return my inverter and wiring etc. and just stick to DC 12V appliances from my panels & battery.

Is a small inverter any safer, or have I got this completely wrong?

https://www.mygenerator.com.au/ener...ave-inverter-with-rcd-ac-transfer-switch.html

Would something like this, with an RCD & AC connection allow me to run it as a portable inverter?

Feels very defeating to realise there's this serious safety issue (grounding / earth) that really isn't addressed anywhere, and nobody really seems to understand.

Definitely not as simple as the YouTube videos say it is. Thanks for the wakeup call everyone.

 

[upnorthandpersonal]

I'm so confused.

That's why I suggest to talk to a local electrician who can tell you exactly what to do for your area instead of just trying to figure stuff out as a non-experienced person with advice from people that are in a completely different system and regulation than you are in.

 

[Hedges]

Electrical safety (shock hazard) does not depend on size of inverter. Just 0.030A and 120V is sufficient to cause injury so safety precautions matter for any size inverter.

If manufacturer says to ground the inverter chassis with a lug they provided on the chassis, do that.

Does your inverter also have an AC input meant to be fed by house wiring or by a generator? That would be an "inverter/charger" and might have a transfer switch inside to either power output from AC input or from the inverter. If so, connecting that AC input would connect ground.

You could take an appliance cord, tape off the two unused power wires to insulate them, and use the ground wire to ground inverter chassis. Then by plugging it into a grounded outlet the inverter chassis will be grounded.

The inverter you have should be fine for use in a dry location. Condensation from steam in a laundry room is bad for electronics (may not be an issue if dryer etc. is well ventilated outside.) If you use it in a wet location or with an extension cord for appliances in a wet location like outside, add an RCD.

The linked "Inverter with RCD & AC Transfer Switch" has a couple of useful features.
"Transfer Switch" means it will operate as an uninterruptable power supply. The outlet is powered from AC grid connection when present, but is transferred to battery power when the grid fails. With suitable PV panels and battery this would run loads continuously.
"RCD" means it has shock protection; if you get a shock from it, the power is quickly turned off.

 

[Dzl]

No, No, No. This is not correct. Not in Australia..... People are replying with things that are only relevant in e.g. the States without taking into consideration that the Australia (and the rest of the world) use different earthing systems.

So much of our info (at least for fixed structures / residential systems) is North America centric and specifically US centric (welcome to the internet..)

We have many sections of US codes and regulations available in the resources section and the code compliancy section. I have probably contributed the majority of them, but I am totally ignorant of what resources and codes apply outside of the US. It would be great if some of our non-American members added resources relevant to other areas of the world. I know we have a good handful of people from Canada, Australia, the UK, and from the EU (has the EU adopted a uniform standard?) I think many people would benefit from resources specific to these jurisdictions and others.

 

[upnorthandpersonal]

It's something that's been on my to-do list for a while, since these discussions keep popping up. Canada is pretty similar to the States, I'll do Europe first, and than the rest. Not sure when yet though.

 

[FilterGuy]

Canada is pretty similar to the States,

Yes. That is correct, but from what I understand there are still some differences. I don't recall the name of the group, but there is a group that is trying to unify the US, Mexico and Canada electrical codes. I have no idea if they are making any progress.