Switching Neutrals

Many bluetti owners contact us regularly asking about units burning up due to not switching the neutral and… You should be using a transfer switch with USA and Canada approved label for inspections. You need to use a switch that transfers both legs, this is a requirement for GFCI, Arc fault and combo breakers also. Any charging unit that will not allow their “neutral” to be grounded must be switched and treated like a hot leg.

Good info but…
I’ve no real interest in a transfer switch since I only need to power 2 things with my Bluetti, a small freezer and a fridge. I can plug the freezer in directly but the fridge’s plug I cannot get to because the builders surrounded it with cabinetry and put an island too close to the front of it. What are my options for powering this dedicated circuit?

You could get a single circuit transfer switch. I couldn’t see a big difference in price between 1 and 6 circuits though so I went with 6.

Transfer switch mounted at the panel

who sells a 6 circuit transfer switch for under $100? AND more important does it switch the neutrals?

Nobody sells any kind of transfer switch for under $100 as far as I know.

I use two EZ Generator Transfer Switches with my AC300 successfully. It switches neutrals so works great with the UPS mode, unlike non-neutral-switching transfer switches.


This post would be more useful if you would state specifically and directly:

  • Are Bluetti units bonded or floating?
  • How exactly should your product (EZGenSwitch) be configured to correctly and safely connect to Bluetti systems?

Your info above may be fine for those who have some working knowledge, but for those of us without… not so much.

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Joule22 …happy to help you , Here goes:
Lets talk about generators or Portable charging units. Bonded neutral means “inside” the unit the “neutral” is physically connected to the casing or grounded to that casing. Floating neutral means the neutral is exactly that …floating and not connected to the ground or case.
Next: the National Electrical Code (NEC) say’s the neutral shall be bonded at the first means of disconnect or in this case at the unit >>> and shall not be bonded any other place/location. This is a safety issue, “we” want to make sure we know the return path of current and that it’s not running willy nilly (like that word) all over looking for its return path. So our switch when converted for floating neutrals “bonds” the neutral to ground and satisfies the NEC . On the other hand when the unit is a “bonded neutral” the code doesn’t want it “bonded” again some where else for reasons mentioned above. So our switch “switches” the neutral and the hot legs independently but together…again a safety issue.
NOW >>> bluetti as well as several others Do Not have a neutral bonded to ground. Think of it as the unit is producing (2) 60 volt legs…you can not ground/bond their “so called neutral”. The unit see’s it as a short to earth rather than a true neutral which is bonded to earth/ground at the first means of disconnect or the unit. You will basically cook that leg and thereby destroying your unit. Use our switch as delivered to avoid this issue, do not convert.
So in conclusion, it is very important to bond the case of your unit to earth via a ground rod of some type. WHY? because if the unit shorts internally that “fault current” will travel to earth and disperse rather than sit there waiting for you to touch what is now a “live” frame looking for ground…and you are its conductor. Hope this helps, tried to keep it simple but if you have more questions just ask!

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Forgot to mention : GFCI or Arc faults will NOT work unless the neutral is switched because that device “see’s” the neutral bonded and will not allow current to flow. Our switch will satisfy this condition also.

OK, thanks, the bolded part of the quote is what I was after, but regarding the grounding of the Bluetti, the case is made of non-conducting materials and no provision exists for grounding the unit. Bluetti asks us to put our faith in their protection circuitry, for better or worse.

So in other words Bluetti inverters like the AC300 have a floating neutral?

This doesn’t make sense to me. Everything I’ve read states that bonded/GFCI generators require a transfer switch that also switches neutral which the AC300 also seems to require so wouldn’t that mean the AC300 has a bonded neutral?

I’m pretty sure the AC200MAX has a floating neutral. If I test it with a outlet tester it shows an open ground.

As far as I understand a portable generator with a floating neutral should have the neutral attached at the panel and should not be switched. I’m not an electrician though.

The issue here only seems to be when you charge the AC300 with utility power that is on the same circuit as the transfer switch. If you are using it as a generator and powering it with solar then you won’t have an issue with a transfer switch that does not switch the neutral.

However, if you want to charge it with utility power and use it at the same time then you need to isolate the neutrals.

As for bonding the case to the earth with a ground rod - that is simply impossible with the AC200MAX as it’s a plastic and rubber case. There is no ground screw to attach to anything.

I think it’s important to note here that the user EZGeneratorSwitch is here to try to sell a product. Even in reply to Joules22 who said they did not want a transfer switch, the response was to buy a transfer switch :slight_smile:

We are here to help endless customers who contact us with either a issue of burning out their unit or “how do we connect”
We suggested Joules22 “who asked us” what they should do >>>> NEVER did we say buy a EZ generator Switch… there are many on the market.
You said" However, if you want to charge it with utility power and use it at the same time then you need to isolate the neutrals." This is a code violation just a FYI

It has a floating neutral which by NEC requires that neutral be grounded BUT >>> according to dr_torch there is a issue connecting it to standard power (we believe he is correct). There in lies the issue, You are grounding the neutral side of the unit per NEC but the unit will fail. We have spoken to Bluetti trying to get answers for our customers and they have as of this date not responded.

Well, @EZGeneratorSwitch I don’t know about everybody else but I am totally confused.

First I should mention that I do not live in the USA and so NEC does not apply to me. But that aside, in your first post you wrote the following:

“You need to use a switch that transfers both legs, this is a requirement for GFCI, Arc fault and combo breakers also.”

So just so we are on the same page, I take that to mean that I need a transfer switch that transfers both the hot and the neutral.

Now on your last post you write:

“It has a floating neutral which by NEC requires that neutral be grounded”

So this means that we should not transfer the neutral?

As far as I understood in Canada (and again I am not an electrician here) if you have a generator with a floating neutral you switch the hots and the neutrals do not get switched.

If you have a generator with a bonded neutral then you are required to switch the hots and the neutrals.

@BLUETTI - can you tell us if the AC200Max and AC300 are floating neutrals or bonded neutral units?

Hey DR…don’t be confused because you are reading it correctly. Even our Canadian peeps ask these questions. We are familiar with your code also, as you can see we are approved to sell in your country. Here goes >>

  1. NEC and Canadian code says briefly: if you have a floating neutral you shall ground the neutral via the transfer switch to the main panel
  2. If you have a bonded neutral you shall not ground the neutral again and there fore switch the neutrals BUT here are the catches:
    Bluetti is floating but you will cook that unit if you ground “their neutral” so what is your option…switch the neutrals and ground the case BUT they make a provision for you to do that !!! This is done “in case” the unit shorts and the case becomes live but Bluetti’s is plastic so you cant. Bluetti will not address this, don’t know why
    They are not the only company with this issue.
    Simple to check if they are floating neutrals . Place a tester from neutral to earth ( real dirt) what do you get? Do the same with the hot leg? What are you getting 60 volts each???
    OR plug into the unit a tester that shows polarity, is it showing open neutral?

DR go to our site Ezgeneratorswitch. and look at the fourth video down on the left " simple explanation of bonded and floating neutral generators"
Glad you are asking these questions because you are helping others.

Hi @dr_torch , AC200max and AC300 are floating neutral units.

Then why does the AC300 have issues if a transfer switch that does NOT switch neutral is used?

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