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

[acdoctor]

Once I installed an inverter in a RV that was wired that way. It was tripping the internal breaker. It took a while but I found a plug that had the bare ground touching the neutral screw but with one reverse polarity I would have never had a clue.

 

[dgallen]

Yes exactly! That's why I said it's only specialized radio equipment. You're right.

It's just the only exception I found. Thought I should mention it anyways.

I think the post you provided from Ria Jairam is an important piece to add to the whole discussion. She has cited a real world example on how the reverse wiring on the TT-30 can be a serious and perhaps even deadly issue. Sure, it may be isolated to a particular use case or equipment category as an early example, but it proves it can happen and other such scenarios could occur.

Will, I've always appreciated your position and advocacy for safety, especially regarding non professionals opening and modifying their power generation devices. It concerns me that your post on this topic has been shared on multiple sites now (including Hobotech and Bluettti Facebook pages) saying that there are no issues whatsoever with the reverse wiring on the AC200Max. In addition DIY instructions are being promoted on these sites to have laymen open and rewire their units... and I'm not sure if many understand the potential danger lurking within.

If you have not seen it, on the Bluetti page a user has posted that the EP500 has a similar wiring reversal and cites the potential safety issues associated with it. This post also gives instructions on how to crack open the case and perform DIY rewiring...

 

[Will Prowse]

Let's have a look at these four AC voltages and get to the bottom of this....

Hot (30A) & Hot (20A)
Hot (30A) & Neu (20A)
Neu (30A) & Hot (20A)
Neu (30A) & Neu (20A)

Finally back home and did test two seconds ago:

120V
0V
0V
120V

 

[Will Prowse]

I think the post you provided from Ria Jairam is an important piece to the whole discussion. She has cited a real world example on how the reverse wiring on the TT-30 can be a serious and perhaps even deadly issue. Sure, it may be isolated to a particular use case or piece of equipment as an early example, but it proves it can happen and other such cases could happen.

I could see specialized radio equipment getting damaged, but how would it be deadly? Or do you mean, destruction of equipment could cause a fire that could be deadly?

I think they should put a disclaimer telling people not to use ham radios with these devices. Or anything that requires a neutral ground bond.

 

[ShedLab!]

Finally back home and did test two seconds ago:

120V
0V
0V
120V

Conclusive! Now why would they do that? lolz. Is it a mistake? I see what you mean now about tying all the grounds together.

 

[dgallen]

I could see specialized radio equipment getting damaged, but how would it be deadly? Or do you mean, destruction of equipment could cause a fire that could be deadly?

I think they should put a disclaimer telling people not to use ham radios with these devices. Or anything that requires a neutral ground bond.

Apologies Will, I was in mid post and hit carriage return. My full post now appears. thx.

 

[Bud Martin]

According to Will, the Bluetti AC output is floating system, the Ground is not tied to any pole of the AC output.
Read page 56 and on:

https://www.victronenergy.com/upload/documents/Wiring-Unlimited-EN.pdf

 

[740GLE]

IMO in a world of regulations, codes and standards they are there for a reason, and I feel a big portion is consistency.

There’s a million different ways to skin a cat or wire a system and still “work”, no one will be killed, but it’s still not right and posses an unneeded risk to a system that has high consequences . It’s these codes and specifications that take out that risk and minimize errors.

It’s clearly fact that this device is on the market that doesn’t meet a known code/specification. The company even admitted it and knows it’s an error and is willing to address it (a running model rev change if I’m not mistaken). I’m more curious of how this error came from design, into production, and out in the publics hands. Did this design save on the bill of materials, did someone think, hey we can save $0.03 a unit by doing this, no one will notice. Was it gross incompetence?

The risk in continuing to produce a product that isn’t to specification (and may cause harm to maybe only .00001% of users) isn’t a risk the company is willing to take.

IMO any discussion explaining how a mistake “is fine” and down playing an error as “not a big deal” doesn’t do anyone any good other than to stroke the marketing egos of the company producing said flaw.

This kind of reminds me of a couple o rings that “met spec” and had proper tolerances, yet a bunch of people knew of a flat out error, others thought it wasn’t a big deal and accepted the situation “as fine”. . .

 

[Zil]

Wow. Lots of air. In any ac circuit there is no neutral until one side is bonded to ground (green). Better hope the side that gets bonded is the same side throughout the system.

 

[K8MEJ]

I think they should put a disclaimer telling people not to use ham radios with these devices. Or anything that requires a neutral ground bond.

I'm being nitpicky I know, but this isn't an issue with ham radios, per se. If you have an over-the-air TV antenna on a mast and connected to your TV in this situation, it could cause a similar fault. If the TV antenna is installed properly, the mast should be bonded to the same Earth ground as the home's primary electrical panel Earth ground. Same with someone living in a fringe reception area that wants to receive FM radio broadcast. Or GMRS radios, etc. Ria's point is that we usually share a common ground with the shield of the antenna, the case of the radio equipment, and (if installed properly), a single Earth reference ground (even if there are multiple ground rods, they are all tied together as one reference).

Is it likely for most people? No. Is it possible, very certainly.

 

[Will Prowse]

IMO in a world of regulations, codes and standards they are there for a reason, and I feel a big portion is consistency.

There’s a million different ways to skin a cat or wire a system and still “work”, no one will be killed, but it’s still not right and posses an unneeded risk to a system that has high consequences . It’s these codes and specifications that take out that risk and minimize errors.

It’s clearly fact that this device is on the market that doesn’t meet a known code/specification. The company even admitted it and knows it’s an error and is willing to address it (a running model rev change if I’m not mistaken). I’m more curious of how this error came from design, into production, and out in the publics hands. Did this design save on the bill of materials, did someone think, hey we can save $0.03 a unit by doing this, no one will notice. Was it gross incompetence?

The risk in continuing to produce a product that isn’t to specification (and may cause harm to maybe only .00001% of users) isn’t a risk the company is willing to take.

IMO any discussion explaining how a mistake “is fine” and down playing an error as “not a big deal” doesn’t do anyone any good other than to stroke the marketing egos of the company producing said flaw.

This kind of reminds me of a couple o rings that “met spec” and had proper tolerances, yet a bunch of people knew of a flat out error, others thought it wasn’t a big deal and accepted the situation “as fine”. . .

Agreed!! I am just wondering why three different companies all did the same thing. Are all of these electrical engineers wrong? I would rather discuss it with others to know what their logic is. We maybe missing something.

If it was one company, and I found this "mistake" during a tear down, I would criticize them. But when three different huge companies, who have the funds to hire qualified professionals, all make the same "error"... I question my own competency. There has to be a reason.

 

[740GLE]

My guess is even though there are three separate companies maybe there is a holding company/conglomerate or investment firm that ruling them all?

Or maybe all three subcontract engineering to a design firm who doesn’t really care much beyond getting paid for the least cost design. Then the companies slap fancy colorful cases over the guts and sling them across the ocean at us.

Either way 1, 3 or 10 companies improperly doing something to make a profit doesn’t make it right.

 

[FilterGuy]

But when three different huge companies, who have the funds to hire qualified professionals, all make the same "error"

That is a reasonable observation, but you may be a bit too generous. I certainly have no insight into the companies, but there is an assumption in the statement that the engineers at these companies are in fact capable and qualified. Getting the two wires swapped is a relatively easy mistake and if the engineers are not paying close attention they could get it wrong. In fact, the mistake could easily have been made when the instructions to the production line workers were developed. (They were probably not developed by the primary engineers)

Here are two diagrams I found for the TT30 plug. Which is correct?



The answer is that they are both correct. One is for female receptacles and the other is for male plugs.

Furthermore, we have all seen knock-offs from china where one company copies another company's product. It is plausible that one got it wrong and others copied it.

 

[time2roll]

We would be better off scrapping the legacy step child TT30
Perfectly good 5-30 is less confusing in several ways.

 

[ShedLab!]

The Hot Neutral convention is well understood for the 15A receptacles. Honestly, I had no idea which is the conventional neutral for the relatively obscure RV plug - I've never even seen one. Maybe they just made an honest mistake? It’s not like one of the slots is obviously longer....

It's better to wire it conventionally for many reasons.

 

[Bud Martin]

It seems to me that they have poor QC and the test procedures are not being done, checking the inlet/outlet polarity is one of the test step I write for test procedures of the products I design, the products also have gone through compliance testing with test certificates, we also have surprise inspection visit from compliance companies, UL, ETL, TUV, and CSA. Compliance testing is VERY expensive.
The AC200P is tested per UL standard by TUV, I do not know if all other models have certificates or not. BTW, EU uses non-polarized harmonized Schuko plug/receptacle even though they do have one pole bonded to safety Ground ( I verified that when I visited my sister in France), some how they can sell Toaster that only break one side of the Line. The products I design for EU must use double pole power switch per compliance.

 

[Porch]

So all the grounds between all the plugs, are all interconnected to each other, but they don't connect to anything else? Do they connect to the negative on the DC side of any of the inputs or output?
Do the AC neutrals also connect to any of the DC negative lines?

Assuming all the grounds interconnect to each other, and also assuming the ground and neutral is bounded in an RV that is plugged into the RV socket (many are due to the generator). This in affect, makes the ground bonded with the hot. And it also transfers this to an earth ground by the RVs metal feet, water line, or anything else.

So now if you plug in a faulty device that has the neutral and ground bonded, you get a short. Or, if you happen to touch something that has the neutral exposed (like a screw in lamp socket) and you are standing on the ground, you get a shock.

Also, if any of the DC inputs or outputs are bonded with the AC grounds, that could cause the same shocking hazard.

It's one of those things that would take 2 things going wrong in order to create a electrical hazard, but the electrical/safety standards are written in the blood of those died. I would not call the plug being wired backwards acceptable.

 

[dgallen]

Assuming all the grounds interconnect to each other, and also assuming the ground and neutral is bounded in an RV that is plugged into the RV socket (many are due to the generator). This in affect, makes the ground bonded with the hot. And it also transfers this to an earth ground by the RVs metal feet, water line, or anything else.

I was thinking the same thing. It is common practice to attach appliance ground wires to the chassis of the RV. Metal stabilizer jacks on every corner, trailer jack on the tongue all connect to the ground which are frequently in wet conditions. Yes often these use wood or rubber pads to stand on, but also things like safety chains that are attached to the tongue, rest of the ground when not hitched to the tow vehicle.

 

[Porch]

I was thinking the same thing. It is common practice to attach appliance ground wires to the chassis of the RV. Metal stabilizer jacks on every corner, trailer jack on the tongue all connect to the ground which are frequently in wet conditions. Yes often these use wood or rubber pads to stand on, but also things like safety chains that are attached to the tongue, rest of the ground when not hitched to the tow vehicle.

The issue is that the two types of plugs are wired backwards to each other. So if there is a RV/Trailer plugged into one outlet, and another trailer plugs into another outlet, then this creates a short. This is all assuming all the grounds on all the AC plugs on the Bluetti are connected, but to each other only.

I want to know if the DC side negative is connected to the AC side ground or neutral. That can cause more issues with the onboard battery chargers (or generator) bonding the AC neutral to the DC negative.

 

[Will Prowse]

Update: just realized this is for the ep500pro. They must have sent these to me by mistake because I don't have that model.

Ok get this!! Just got the fusion box and I found a few issues instantly. The ac300 ac200 max have a tt-30, but the fusion box has L14-30 male prong plugs!! They don't connect at all. How bizarre!

Also notice all the mistakes posted on the fusion box sales brochure. The labeling for the plugs is incorrect.

There's also a relay on the 240V outlet plug for one of the hot conductors. I am guessing that it tests to see if everything is connected properly, then it allows you to safely use the plug.

Having the improper plugs confuse me to no end. I hope they didn't make a million of these!

Very nice build quality though. Looks great otherwise.