Reverse Polarity RV Plug on Bluetti/Ecoflow/Goalzero?? Is this a problem?

[Will Prowse]

Not complete for how the typical split phase power is designed. The neutral comes from the center tap of the transformer and has virtually no voltage potential. The neutral acts like a drain. The hot comes off the end of the coil and has the voltage potential. Yes technically the potential alternates between positive and negative. The hot is very different from the neutral as the hot has the power and voltage potential.

Devices and appliances are designed to cut the hot side to remove power from the internal components and reduce potential faults.

Think of the hot as the faucet and the neutral as the drain. All works great when the faucet has the valve. Putting the valve on the drain is asking for trouble.

This is why plugs and connectors are polarized. Yes the portable generator being isolated reduces the risk. That is great when the generator is outside on the dirt. More potential issues if the generator is mounted and operating in an RV compartment as many do.

These generator with reverse polarity need to be used with due caution or returned as defective. JMHO.

None of these points are relevant in a floating system. We are not talking about center tap transformers and the reference potential of grid tied ac systems. We are talking about the ac output from an inverter that is not earth grounded. It does not act as a faucet and drain. It may be easy to imagine in your mind with this anology, but it's not true. Both conductors on the output of a inverter circuit switch polarity rapidly to energize the circuit and transmit energy. If you complete the circuit, you will get shocked regardless. There is no output conductor that has the same potential as you, except for ground, because it's not connected to anything (in bluetti and ecoflow)

In grid systems, there needs to be a reference potential for quite a few reasons. That is why you have a ground and neutral. But it is still alternating current, so polarity does not exist. For safety, the potential of hot does matter in a earth tied system.

 

[740GLE]

So this product isn’t safe for a permanent cabin/tinny house installed system with a breaker panel and grounded neutral, until redesigned/recalled.

With the PV input capability of this system it’s hard to say this a “portable” system where being ungrounded it’s not an issue.

I fear many people just see that 30a plug and figure it’s a perfect solution that covers tons of needs for a modest sized system.

IMO if the company advertises a 30a plug as such, yet that plug isn’t wired to accepted standards, that’s false advertising and should not be recommended for any install.

 

[John Frum]

I looked at this ^ picture and very quickly came up with the mnemonic "white on the right".
On the 3rd or 4th look It dawned on me that "white on the right" depends on the orientation of the ground pin.
In the picture above all ground pins are at 12 o'clock.
On the Bluetti AC200 the 5-20r ground pins are oriented at 6 o'clock.
Still doesn't explain how multiple products got this wrong though.
Just an observation.

I think that the manufacturer should either...

Isolate each ground pin
or
Swap the hot and neutral on the tt-30 plug

Because these exist

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

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

www.amazon.ca

If a bonding plug is used and an RV is plugged in...
The breakers and switches will be on the neutral leg.
That means a ground fault will bypass the over-current protection and switches.
And circuits with a switch will be hot through the load and back to the load side of the switch.

Hope this makes sense.
If I'm wrong I want to hear about it.

 

[Will Prowse]

So this product isn’t safe for a permanent cabin/tinny house installed system with a breaker panel and grounded neutral, until redesigned/recalled.

With the PV input capability of this system it’s hard to say this a “portable” system where being ungrounded it’s not an issue.

I fear many people just see that 30a plug and figure it’s a perfect solution that covers tons of needs for a modest sized system.

IMO if the company advertises a 30a plug as such, yet that plug isn’t wired to accepted standards, that’s false advertising and should not be recommended for any install.

None of these units are designed for code compliance at all. Redesign or recall won't help either because you will need to create your own earth ground or leave it floating depending on what your needs and your environment (lightning prone areas etc). You can make these systems work for anything you wish depending on how you wire the output and what devices and safety systems you add on your own.

Ungrounded is fine. Not sure what your point was with your second line. What do you mean?

If you use the RV plug by itself, regardless of polarity, it will work. Unless you used specialized radio equipment.

Well that plug can't even provide 30A. It is more like 18A. I do not think they should have the plug at all, the inverter is too small. I think a terminal block would be more fitting. On the side of the unit for example.

 

[Short_Shot]

We don't even have polarized plugs on mainland Europe, and equipment needs to work no matter where phase/neutral are in the socket. I can't imaging there be many products even in the States that rely on the polarity...

As I recall there are a few cases where it matters but mostly it's a safety issue with some crappy old appliance designs.

 

[Will Prowse]

View attachment 72697

I looked at this ^ picture and very quickly came up with the mnemonic "white on the right".
On the 3rd or 4th look It dawned on me that "white on the right" depends on the orientation of the ground pin.
In the picture above all ground pins are at 12 o'clock.
On the Bluetti AC200 the 5-20r ground pins are oriented at 6 o'clock.
Still doesn't explain how multiple products got this wrong though.
Just an observation.

I think that the manufacturer should either...

Isolate each ground pin
or
Swap the hot and neutral on the tt-30 plug

Because these exist

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

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

www.amazon.ca

If a bonding plug is used and an RV is plugged in...
The breakers and switches are on the neutral leg.
That means a ground fault will bypass the over-current protection.
And circuits with a switch will be hot through the load and back to the load side of the switch.

Hope this makes sense.
If I'm wrong I want to hear about it.

The OCPD will still work on neutral. Try it out. Try overloading the circuit when switching the polarity. It will trip it just fine. The circuit breaker will still sense an over current event regardless of where you wire it. You need both conductors to carry the current and a fault to trip OCPD. Some people think that the ground is for over current fault mitigation, and that is not true.

In a DC system, you should put the breaker on the positive side because I have read it has a slightly higher potential, but it will still trip regardless of where you put it. Some new batteries put the OCPD on the negative side. Shunts can be on positive or negative as well, but usually its put on the negative side.

Also keep in mind that in earth ground ac systems, the earth ground serves no purpose in tripping any circuit breaker. OCPD is for fault mitigation when a load exceeds a specific current rating for a certain amount of time (depending on what breaker you have). The ground is not serving as a path for current to trip the breaker or fuse.

 

[Will Prowse]

Keep in mind that there is no "hot" or "neutral" in a floating system. They are both hot, and both are required to complete a circuit. Safety wise, there is no difference between them. Both will shock you if you complete the circuit with your body.

If you add an earth ground, or use devices that require an earth ground to neutral bond, or need a reference potential for your system to be used as a sink for excess charge accumulation or something else, then you absolutely do need to differentiate between hot and neutral and run an appropriate grounding conductor. But in a floating system, it does not exist.

 

[John Frum]

Try it out.

I'm not able to test that for the foreseeable future.
Just to be clear I'm taking about ground faults.

Consider the following scenario.
RV user uses the bonding plug I described earlier in the thread.
User has a metal frame appliance with 3 prong plug.
The neutral wire in the appliance shorts to the appliance frame due to shoddy workmanship.
The ground wire carries the current back to source.
Because the ground wire is bonded to the effectively hot leg the current is split between the hot and ground wires and the breaker may not trip.
Even if it the breaker does trip the fault current will still flow on the ground.
I could be wrong but I call it like I imagine it.

Updated with link to drawing:

latest drawing

There is a hidden "hover" menu bottom center to navigate from page to page.

 

[Short_Shot]

I'm not able to test that for the foreseeable future.
Just to be clear I'm taking about ground faults.

Consider the following scenario.
RV user uses the bonding plug I described earlier in the thread.
User has a metal frame appliance with 3 prong plug.
The neutral wire in the appliance shorts to the chassis do to shoddy workmanship.
The ground wire carries the current back to source.
Because the ground wire is bonded to the effectively hot leg the current is split between the hot and ground wires and the breaker may not trip.
Even if it the breaker does trip the fault current will still flow on the ground.
I could be wrong but I call it like I imagine it.

I'm no expert here but as I understand it a gfci will still work because they detect an imbalance in current between both hot and neutral. So if you ground it to your RV that's current going someplace other than where it should and it'll still trip.

But don't quote me on that until more information can be achieved.

You can test it easily though by just shoving a wire from the gfci ground to... the ground, wiring hot and neutral to the floating system and hitting test.

A circuit breaker on the other hand may not trip as you said.

 

[740GLE]

My point is, up until this point the design and intent of devices these companies have manufactured and marketed have been relatively small and limited (no 30a plugs? Limited PV input, limited AC output, limited KWHr storage)

IMO people never saw these smaller units as suitable for permanent installations of higher demand/usage.

By having this unit with such high PV input capability, high AC output, huge scalability of storage, many will assume it’d be perfect for a quick install in a camp with a wired house/brk panel install.

They’d assume the 30a plug is wired per standards and connect it as such, yet will be mistaken.

Sure I listed a lot of “assumptions” of those buying the unit, but again that’s why standards are there to remove errors in assumptions.

This also speaks to ever person who reviewed this product before launch for YouTube views, they assumed this 30a plug was wired correctly, they never checked it and brought it up as an issue, they reviews the fancy features and capability of the unit, but glossed over critical details of the system.

 

[time2roll]

I'm not able to test that for the foreseeable future.
Just to be clear I'm taking about ground faults.

Consider the following scenario.
RV user uses the bonding plug I described earlier in the thread.
User has a metal frame appliance with 3 prong plug.
The neutral wire in the appliance shorts to the chassis do to shoddy workmanship.
The ground wire carries the current back to source.
Because the ground wire is bonded to the effectively hot leg the current is split between the hot and ground wires and the breaker may not trip.
Even if it the breaker does trip the fault current will still flow on the ground.
I could be wrong but I call it like I imagine it.

Very common and ordinary with a small Honda generator that people have been using safely for decades.

 

[740GLE]

Honda generators have 30a plugs wired incorrectly?

 

[time2roll]

Honda generators have 30a plugs wired incorrectly?

No. The Honda 5-20 connector has a floating neutral same as this generator. Use a common 15-30 adapter and it will test the same just before hundreds of RVs plug in every day.

 

[upnorthandpersonal]

I'm no expert here but as I understand it a gfci will still work because they detect an imbalance in current between both hot and neutral. So if you ground it to your RV that's current going someplace other than where it should and it'll still trip.

But don't quote me on that until more information can be achieved.

I'm only addressing this point, I'm not getting involved with American plug standards and neutral bonding stuff.

An RCD, GFCI etc. work perfectly fine in a floating system. I use that in the lab where we have training systems that are floating and are specifically used to test and train on substation automation stuff (IEC61850). RCD's are required in TT type ground networks for example because of the high impedance and thus very low fault current that can't trip an over-current protection device.

 

[sunshine]

They’d assume the 30a plug is wired per standards and connect it as such, yet will be mistaken.

The live and neutral do seem to match the Australian Standard for their respective location.
No US Standards to meet before selling over there to the general consumer?

 

[Bud Martin]

Isolation transformer output (floated), I use this at home, I use TAPAZ Ultra isolation in the lab at work.

 

[Bud Martin]

The safety ground wire used in the Nentral bonded to ground system is for fault current and must be rated to handle fault current in case shorts circuit of hot wire to the grounded chassis occurs.
Also see Victron info about floated AC:

 

[upnorthandpersonal]

Also see Victron info about floated AC:

One important omission in that document is that on an floating (ungrounded) system you actually would need 2 faults to get current to flow outside the normal current path. The first fault grounds the floating system, the second fault creates a path for unintended current flow. Therefor the last sentence in that document: "Although the system might have an RCD, but the RCD cannot detect an earth leakage current anymore because the Neutral is not connected to earth." is not entirely correct.

 

[philatio]

Well, now that I am thoroughly confused, I am wondering about my use case with my Bluetti system.
The house is all prepared with a 10 circuit transfer switch and an L14-30 inlet box. All installed by an electrician.

I am waiting on my 2 x AC300 + 4 x B300 + Fusion Box Pro. I intend on using the system as if it were a generator. I will be using the L14-30 on the fusion box pro ac out to connect to the L14-30 inlet box.

Should I be worried/reconsider my choice?

 

[John Frum]

Well, now that I am thoroughly confused, I am wondering about my use case with my Bluetti system.
The house is all prepared with a 10 circuit transfer switch and an L14-30 inlet box. All installed by an electrician.

I am waiting on my 2 x AC300 + 4 x B300 + Fusion Box Pro. I intend on using the system as if it were a generator. I will be using the L14-30 on the fusion box pro ac out to connect to the L14-30 inlet box.

Should I be worried/reconsider my choice?

View attachment 72872

I want to know if their is anything hinky with the fusion box pro wiring?
I think its reasonable at this point that every product from every company in this market segment should be checked.