Inverters - bonded/floating ground and reversed hot/neutral

[harrymanimus]

I have two products with inverters that failed to run my home furnace during the Feb winter storm. I had to run a small space heater which was just passable to keep our bedrooms in the 50s. I was super close to being ‘hero level prepared’, but no cigar.

After some research, I determined that the issue running the furnace was an open ground and the furnace required bonded. It tried to work, it ran, but blew cold air and reset itself after X minutes.

Outlet tester results:

EcoFlow 1300 Portable Power Station - Open Ground
Handy Power X 1500w inverter - Hot/Neutral Reversed (Fun!)

I bought this adapter.
https://www.amazon.com/dp/B07F4R7BDL/ref=cm_sw_em_r_mt_dp_B5NG3EP13RQGCHY7H7QY?_encoding=UTF8&psc=1

1. Tested this on a gas/propane generator and the outlet tester reported a bonded neutral. Works as intended.
2. Tested on Ecoflow, no change, does not work.
3. Tested on HandyPowerX. As soon as I plug it in the protection light came on, and the inverter power shut off. Big time fail.

How can I make my 2 devices work? I’d prefer to have the Handy Power X work as that will last a long time on a tank of gas.

I found this youtube video that seems like it will provide a bonded ground for these inverters. Video - How to build a dummy plug. Before I do this I’d like to have an idea that it will work/be safe enough for emergency usage. Since the Handy Power X reports Hot/Neutral reversed, I supposed I’d have to reverse those in a built adapter?

Thanks!

 

[Ampster]

Lets start with the furnace and fan first if I correctly understand that you want to run it when the power is out? In order to do that we need more details on your furnace? Is it just the fan with a gas heat source? What is the voltage of the fan? Can you identify the circuit breaker that controls the circuit that the furnace is on?
Did your devices run your space heater? Can you get your devices to run a light bulb or a small space heater to eliminate them as an issue? It was unclear whether the space heater ran off those devices or if it had its own source of heat such as propane.

 

[John Frum]

The ecoflow is a 2 prong receptacle with a big hole where the ground pin would go so its definitely floating ground.
My guess is the handy power we be 60 volts hot to ground and 60 volts neutral to ground and 120 volts between hot to neutral.
For the ecoflow I have heard of people using one of these.

Southwire Company LLC Neutral-Ground Bonding Plug : Amazon.ca: Electronics

Southwire Company LLC Neutral-Ground Bonding Plug : Amazon.ca: Electronics

www.amazon.ca

In order to use the ecoflow you plug a power bar into the eco flow and you plug the bonding plug into the power bar.
Then you plug the tester info the power bar and if it shows a proper test result
Plug the furnace into the power bar.

 

[GXMnow]

When you are connecting your power station or generator, are you completely disconnecting from your main panel? In the past, I installed a generator transfer panel. That only switched the hot legs. The neutral and ground stay connected to the main panel which takes care of the ground bond. That works perfect on a generator with a floating ground.

On the Handy Power X with the hot and neutral reversed, that is just plain wired wrong. Are you sure the hot pin has no volts on it? If so, re wire the socket properly and you should be good. But it may be worse than that. I have a really cheapo modified sine inverter that does not have a real neutral. Both legs swing 60 volts from the battery ground, but out of phase, just like split phase 120/240, but this is 60/120. If you ground either pin to the battery ground, it just shuts off. The proper "fix" for this is to use an isolation transformer. But they can get pretty expensive. Here are a few options from Amazon

Amazon.com : isolation transformer 120v

Be sure it says "isolation" in the description. Many of the voltage conversion ones do not isolate. As you need more wattage, the price climbs.

A cheap fix that can work on some inverters, is to ground the one side of the output to make a bonded neutral, but then you need to isolate the inverter completely. If the battery is left with both legs floating, you can ground the neutral and it will work. But make sure to isolate and insulate the battery leads as the battery negative will now be swinging at 60 volts. And the case of the inverter, might also be energized. So mount it in a plastic enclosure so no one can touch in. Mine has the case isolated, so that was not a problem. Then you ONLY use the "neutral" and hot leads. The neutral will tie to the ground that is grounded to your house ground wiring. This is a temp use only thing, and can work in an emergency, but it can be dangerous.

 

[Terrapin]

I just know in my gut that this is super important but it eludes me because of my lack of the what, how and whys of phase terminology and bonding, isolation ect.

The more I try to learn about this the more dangerous I feel. I just know this ties in directly with the UL-458 rating I questioned here regarding plugging my trailer into a solar generator I just built. There are so many people on youtube touting this it's horrifying...but I don't know what to do because i don't know why.... https://diysolarforum.com/threads/ul-458-whats-the-worst-that-could-happen.20744/

I think I may be asking too much for a education in AC theory by anyone here. So maybe if anyone knows of a free novice online education resource or video series on you tube about AC theory so I can keep my family safe from me I would greatly appreciate a link or push that direction.

 

[John Frum]

I just know in my gut that this is super important but it eludes me because of my lack of the what, how and whys of phase terminology and bonding, isolation ect.

The more I try to learn about this the more dangerous I feel. I just know this ties in directly with the UL-458 rating I questioned here regarding plugging my trailer into a solar generator I just built. There are so many people on youtube touting this it's horrifying...but I don't know what to do because i don't know why.... https://diysolarforum.com/threads/ul-458-whats-the-worst-that-could-happen.20744/

I think I may be asking too much for a education in AC theory by anyone here. So maybe if anyone knows of a free novice online education resource or video series on you tube about AC theory so I can keep my family safe from me I would greatly appreciate a link or push that direction.

The alternating current part is only a small part of the neutral ground bond issue.
The bigger part is voltage over ~30 volts gets progressively more dangerous especially if there a huge amount of current to go with it.
AC is probably less dangerous than DC at the same voltage.
If you want to learn more you can PM to indicate your interest.
If not I will stop here.

 

[time2roll]

Start by verifying the reverse N-H condition with your voltmeter.
Measure the outlet as shown in the red triangle and post the results.
May also have a floating neutral with 60 volts to ground.

 

[harrymanimus]

I was directly connected to my furnace, disconnected the 120v furnace from the home power. It was drawing around 650w when the fan was running off the EcoFlow.

smoothJoeys suggestion of the adapter in the power bar sounds like it might work. I'd test it now, but unfortunately I left the adapter out of town with my gas generator.

That would get my EcoFlow working for the furnace, which is a great start but not ideal for running more than an hour. I do charge the EcoFlow with the Handy Power X and that works fine. So I could have the EcoFlow powered by the HPX, and the EcoFlow powering the furnace. Not ideal.

The Handy Power X seems like a quality build, heavy gauge everything etc, has pure sine wave output, seems to work well for normal household appliances. Since this video shows how to make an dummy Video - How to build a dummy plug, if I make this and swap the hot/neutral, will that likely work? If I can avoid opening the thing up and jacking with wires and wiring I'd really like to do that.

 

[GXMnow]

On that Handy Power X, you first need to determine if it is hot grounded, 60-0-60 split phase, or floating. Do the test that time2roll suggested with a meter, with and without a load on it to see what you get. Also connecting a small 20watt or so light bulb from the ground to the hot or neutral will show if it is putting out current when referenced to ground. A volt meter does not supply much load and it could float and show voltage where there is no real power.

Connecting a trailer to shore power or a generator does pose a few challenges. When you connect to shore power, the neutral and ground should be fully isolated from each other and both connect to the shore connector. They should be bonded back at the panel in the camp site. When you connect to a generator and are not connected to the grid, then you need to bond the neutral to the ground at the generator, and that ground should be tied to a ground rod. If you are in the middle of nowhere, you may have to bring your own rod and pound it in. Camp site may have a pipe or rod sticking up for you to clamp on to. The main purpose of having this earth ground is to protect from lightning, but it also makes it much safer when you step from damp ground onto the trailer as it will also ensure the chassis of the trailer is not energized. Even a small leakage current could put 100 volts on the trailer frame since it is on rubber tires. A ground rod may seem like a pain, but it is sure better than being zapped when you touch your trailer.

 

[John Frum]

Since this video shows how to make an dummy Video - How to build a dummy plug, if I make this and swap the hot/neutral, will that likely work? If I can avoid opening the thing up and jacking with wires and wiring I'd really like to do that.

Before you do that make sure its not 60 volts from hot to ground.

 

[John Frum]

If you are in the middle of nowhere, you may have to bring your own rod and pound it in.

That is another concept and kind of muddies the water here, no?

 

[harrymanimus]

I’ll do the time2roll diagram and report back. Thanks!

 

[harrymanimus]

Ok, I saw the 60v mentions but did not really understand what that was.

So... I get 45 to 55v Neutral to Ground AND same for Hot to Ground.
Hot to Neutral is 120v.

So it looks like the 60v setup is what this has. And what does that mean for powering equipment that wants a bonded ground? Looks like GMXnow had some suggestions, but I didn't follow. I assume it is ok to be charging my EcoFlow with this.

Since the EcoFlow can act as a UPS and pass power through when fully charged, I can always plug things in like so HPX -> EcoFlow -> Furnace. For emergency purposes.

 

[GXMnow]

I see the trailer question was not from the original poster. I'll keep this on topic.

Since the HPX does appear to be 60-0-60 output, your best bet is to run an isolation transformer. Then ground bond the neutral on the output of the transformer. How much power does the furnace need? Transformers are pretty forgiving on overload for a short time, so just get 100 VA more than the furnace needs while running and it should handle the start surge. The HPX may be able to charge the Eco Flow, but if it does go into a true "Pass Through" mode, that could be a problem as it could also pass through the non neutral.
Here is a good quality unit from Tripp-Lite

Amazon.com: TRIPP LITE IS1000 / ISOLATOR 1000 ISOLATION TRANS 4OUT 6FT CORD 120V 1000W by Tripp Lite : Electronics

Amazon.com: TRIPP LITE IS1000 / ISOLATOR 1000 ISOLATION TRANS 4OUT 6FT CORD 120V 1000W by Tripp Lite : Electronics

www.amazon.com

Quality transformers are not cheap.

 

[Terrapin]

That is another concept and kind of muddies the water here, no?

Muddies the water? This was my intuiyive solution that seemed it should be as basic a part of trailer set up at camp as leveling the trailer. I even referenced seeing utility/fire trucks dragging grounding chains. How can this NOT be a thing when running any inverter system or DC over 12V.

 

[harrymanimus]

I see the trailer question was not from the original poster. I'll keep this on topic.

Since the HPX does appear to be 60-0-60 output, your best bet is to run an isolation transformer. Then ground bond the neutral on the output of the transformer. How much power does the furnace need? Transformers are pretty forgiving on overload for a short time, so just get 100 VA more than the furnace needs while running and it should handle the start surge. The HPX may be able to charge the Eco Flow, but if it does go into a true "Pass Through" mode, that could be a problem as it could also pass through the non neutral.
Here is a good quality unit from Tripp-Lite

Amazon.com: TRIPP LITE IS1000 / ISOLATOR 1000 ISOLATION TRANS 4OUT 6FT CORD 120V 1000W by Tripp Lite : Electronics

Amazon.com: TRIPP LITE IS1000 / ISOLATOR 1000 ISOLATION TRANS 4OUT 6FT CORD 120V 1000W by Tripp Lite : Electronics

www.amazon.com

Quality transformers are not cheap.

I’ll keep the transformer in mind, but since this is for emergency usage that may never happen again, not sure I could justify the purchase. I could limp along just charging the ecoflow without pass through for a few days if necessary. I’ll try to get an answer from support on the EcoFlow “true pass through”. Thanks for the great info and advice!

 

[John Frum]

Muddies the water? This was my intuiyive solution that seemed it should be as basic a part of trailer set up at camp as leveling the trailer. I even referenced seeing utility/fire trucks dragging grounding chains. How can this NOT be a thing when running any inverter system or DC over 12V.

As I said at the top of the thread. Grounding is a complicated multi-faceted concept.
Driving a copper rod into the ground is a different facet.
Now that you have opened the can of worms...

Electrical current tries to get back to its source.
Usually but not always via its polar opposite.

In the case of residential North American mains electricity the transformer is center tapped and this is called neutral.
The transformer center tap(neutral) is bonded to the planet.
Houses are also bonded to the planet at the service entrance.
And the ground conductor is bonded to the neutral conductor at the service entrance.
Having a neutral ground bond means that fault currents don't have to travel through the dirt to get back to the transformer.
That gives the current a path that is low enough impedance to trip the breaker and clear whatever fault condition was present.
The primary reason that everything is connected to the earth via a copper rod or similar is because that nature is teaming with electricity that gets onto our man made circuits.
A notable example is lightning.
Because the transformer is bonded to earth its even more important to have a neutral ground bond that carries fault current that might otherwise go through your body on its way back to the transformer.
Bonding your solar generator to the dirt could potentially make it more dangerous.
Are you more or less confused now?

 

[John Frum]

While we are at it lets talk about volts.
Voltage is relative, same way that altitude is relative.
On earth we reference altitude to sea level and voltage to the dirt.
That is the extent of my understanding and I may be wrong.
I wouldn't be surprised if someone else comes along and make both of our eyes roll back in our heads.

 

[Bud Martin]

Mike Holt:

https://www.youtube.com/results?search_query=mike+holt+electrical+

https://www.youtube.com/user/MikeHoltNEC

Grounding Myth:

 

[Terrapin]

As I said at the top of the thread. Grounding is a complicated multi-faceted concept.
Driving a copper rod into the ground is a different facet.
Now that you have opened the can of worms...

Electrical current tries to get back to its source.
Usually but not always via its polar opposite.


Having a neutral ground bond means that fault currents don't have to travel through the dirt to get back to the transformer.
That gives the current a path that is low enough impedance to trip the breaker and clear whatever fault condition was present.

Because the transformer is bonded to earth its even more important to have a neutral ground bond that carries fault current that might otherwise go through your body on its way back to the transformer.

Tonights homework: "neutral ground bond"

Bonding your solar generator to the dirt could potentially make it more dangerous.
Are you more or less confused now?

No, yes, no. yes lol but..... NO I am good, I do understand my bog down on how it could be more dangerous is simply me not understanding the paths the electrons could choose. ..and terminology. BUT ever so slowly this is starting to come together...but I won't lie and say I got it all together... not by a long shot.

Still, I am not more confused than before, I saw some fog though the fog... And as I keep digging deeper the pieces SLOWLY come together. There can be days till this ties in with something else to make sense in how my brain works...Some stuff just gives you the right direction to dig.

I am having fun with it. potentially dangerous fun but it's a mindset like a language that I WILL decipher. I think my weakness to overcome for the big leap in understanding is to flowchart the potential "fault currents" (what an awesome term) I think this alone is what I have been asking about when asking "what could possibly go wrong" in the other simplistc thread on this topic that I started . How the phase shifts from the OP on this are going to make sense eventually... but for now I gotta just push the chair back from this table till I get some basics down.