Aquarium and electrical safety

[NanoSteam]

It should work if the breakers are AFCI only and not combo.

Note: That sticker is fine there, but it is a good idea to put them on any downstream receptacles connected to the load side of the GFCI.

Got it, I'll add those, thank you!

 

[TX_REEF]

I only read a few pages of this, but didn't see an answer to this one - does wearing the arm-length thick rubber cleaning gloves provide any level of protection?

I have to say honestly, I did not give strong thought to this safety aspect of electrical during the initial phases of my Reef Room, I want to make sure I do everything I can to get in front of potential issues now that I've been reminded of the risks...

 

[Paul B]

After a lot of research, it seems a GFI, even without a ground would work on a battery back up

 

[Freenow54]

After a lot of research, it seems a GFI, even without a ground would work on a battery back up

So am I correct they only are concerned with current flow ie difference ?

 

[Freenow54]

So am I correct they only are concerned with current flow ie difference ?

Whew thanks for that was thinking on not talking at all anymore

 

[BeanAnimal]

I too would like to hear Bean's opinion on how to deal with battery backup safety.

@BeanAnimal

There is no “simple” or straightforward answer, and the explanation will probably confuse some people. Instead of giving direct advice, let me just try to explain how inverter (UPS) and portable-generator outputs differ from your utility power. Sorry, this will be long and a bit technical, there is no way around it.

Most consumer UPS units and small generators have a floating neutral.

That means the neutral isn’t tied to earth ground. Its only reference is the hot. In other words, the only place current can flow (in theory) is between the inverter’s HOT and its own derived NEUTRAL.

Think of a battery. The only place current can flow is between its two terminals. If you touch only the positive terminal, even standing in a puddle, nothing happens. A floating inverter output is basically the same idea (ignoring AC vs. DC). Its two output terminals can only (in theory) pass current between each other.

With your utility supply, the NEUTRAL is bonded (electrically connected) to EARTH GROUND at your service panel. So if you touch utility HOT while you’re grounded, current will flow from HOT through you to GROUND, partly or fully bypassing the neutral. That’s the fault path a GFCI is designed to detect.

With a floating source, touching HOT while grounded doesn’t create that path. There is no path to ground. So (in theory) you don’t get shocked.

---

“Hey Bean! That sounds great, my UPS or generator can’t shock me!”
No. It can absolutely shock you!!
If you grab HOT and NEUTRAL from the floating source, you will get shocked. You just become the load.

In a bonded system you would also get shocked if you grab hot and neutral. The difference is crucial to understand: if you are grounded, a GFCI would trip because some of the current leaks to ground. In a floating system, there is no neutral-to-ground reference at all, so the GFCI has nothing to compare and will not trip.

If you are grounded is a very important caveat. In a bonded system if you are insulated and touch hot and neutral, you also become the load and the GFCI can't help you.

So on one hand, the floating system can be called “safer” because the typical line-to-ground fault doesn’t exist. On the other hand, there is zero protection for a line-to-neutral fault, and the system is not GFCI protectable.

I leave it to you to decide if it is safer or more dangerous overall. I think many who understand these systems would argue that line-to-ground faults are more common (frayed hot wire, hand in water, feet on floor... or face against faulting fixture, hand in grounded tank) and these faults are far less likely in a floating system. They would likely point out that in a floating system, just as in a bonded system, the GFCI offers minimal protection for line-to-neutral contact and only helps in the line-to-neutral scenario if the person is also grounded.

---

“Hey Bean! What is all this ‘in theory’ nonsense?”

We say “in theory” because depending on how the source is built, some tiny amount of current can leak to ground — transistor base drive, generator excitation, internal filtering, other complex faults, etc. So even in a floating system chances of ground fault are not mathematically zero and from a safety perspective you should not treat the floating output any differently.

---

"Hey Bean! What about using them anyway for when the UPS or power station is delivering mains power?"

Well that depends on how your UPS or power center is built. You MUST check the documentation. Many UPS system will pass neutral through (bonded) when on Mains Power and switch to floating when on battery. So on mains power, the GFCI behaves as expected,

However many power centers like Jakery, or Bluetti or EcoFlow derive their outputs from their inverters 100% of the time, so they are always floating.

After a lot of research, it seems a GFI, even without a ground would work on a battery back up

So am I correct they only are concerned with current flow ie difference ?

They only care about the imbalance between hot and neutral. That part is correct.

But the key point (and why this gets confusing) is that a downstream GFCI can only see an imbalance if the system has a neutral-to-ground reference. On a bonded system, a line-to-ground fault creates that imbalance and the GFCI trips. On a floating UPS/generator output, there is no reference, so there’s no imbalance, so it won't typically trip. But back to the "in theory" part, as depending on how the device is built, there could be enough leakage current for it to trip.

The end...

 

[Reefering1]

There is no “simple” or straightforward answer, and the explanation will probably confuse some people. Instead of giving direct advice, let me just try to explain how inverter (UPS) and portable-generator outputs differ from your utility power. Sorry, this will be long and a bit technical, there is no way around it.

Most consumer UPS units and small generators have a floating neutral.

That means the neutral isn’t tied to earth ground. Its only reference is the hot. In other words, the only place current can flow (in theory) is between the inverter’s HOT and its own derived NEUTRAL.

Think of a battery. The only place current can flow is between its two terminals. If you touch only the positive terminal, even standing in a puddle, nothing happens. A floating inverter output is basically the same idea (ignoring AC vs. DC). Its two output terminals can only (in theory) pass current between each other.

With your utility supply, the NEUTRAL is bonded (electrically connected) to EARTH GROUND at your service panel. So if you touch utility HOT while you’re grounded, current will flow from HOT through you to GROUND, partly or fully bypassing the neutral. That’s the fault path a GFCI is designed to detect.

With a floating source, touching HOT while grounded doesn’t create that path. There is no path to ground. So (in theory) you don’t get shocked.

---

“Hey Bean! That sounds great, my UPS or generator can’t shock me!”
No. It can absolutely shock you!!
If you grab HOT and NEUTRAL from the floating source, you will get shocked. You just become the load.

In a bonded system you would also get shocked if you grab hot and neutral. The difference is crucial to understand: if you are grounded, a GFCI would trip because some of the current leaks to ground. In a floating system, there is no neutral-to-ground reference at all, so the GFCI has nothing to compare and will not trip.

If you are grounded is a very important caveat. In a bonded system if you are insulated and touch hot and neutral, you also become the load and the GFCI can't help you.

So on one hand, the floating system can be called “safer” because the typical line-to-ground fault doesn’t exist. On the other hand, there is zero protection for a line-to-neutral fault, and the system is not GFCI protectable.

I leave it to you to decide if it is safer or more dangerous overall. I think many who understand these systems would argue that line-to-ground faults are more common (frayed hot wire, hand in water, feet on floor... or face against faulting fixture, hand in grounded tank) and these faults are far less likely in a floating system. They would likely point out that in a floating system, just as in a bonded system, the GFCI offers minimal protection for line-to-neutral contact and only helps in the line-to-neutral scenario if the person is also grounded.

---

“Hey Bean! What is all this ‘in theory’ nonsense?”

We say “in theory” because depending on how the source is built, some tiny amount of current can leak to ground — transistor base drive, generator excitation, internal filtering, other complex faults, etc. So even in a floating system chances of ground fault are not mathematically zero and from a safety perspective you should not treat the floating output any differently.

---

"Hey Bean! What about using them anyway for when the UPS or power station is delivering mains power?"

Well that depends on how your UPS or power center is built. You MUST check the documentation. Many UPS system will pass neutral through (bonded) when on Mains Power and switch to floating when on battery. So on mains power, the GFCI behaves as expected,

However many power centers like Jakery, or Bluetti or EcoFlow derive their outputs from their inverters 100% of the time, so they are always floating.



They only care about the imbalance between hot and neutral. That part is correct.

But the key point (and why this gets confusing) is that a downstream GFCI can only see an imbalance if the system has a neutral-to-ground reference. On a bonded system, a line-to-ground fault creates that imbalance and the GFCI trips. On a floating UPS/generator output, there is no reference, so there’s no imbalance, so it won't typically trip. But back to the "in theory" part, as depending on how the device is built, there could be enough leakage current for it to trip.

The end...

Hey Bean, what about using the ups and building's line as inputs behind a transfer switch with a gfci and ground probe on its output??
If the line ground and ups nuetral were bonded via that sub panel/ junction, would that eliminate these risks? Is it necessary? Can you think of unintended side effects(faults) ?

 

[BeanAnimal]

Hey Bean, what about using the ups and building's line as inputs behind a transfer switch with a gfci and ground probe on its output??
If the line ground and ups nuetral were bonded via that sub panel/ junction, would that eliminate these risks? Is it necessary? Can you think of unintended side effects(faults) ?

It all depends on the specific UPS topology. I would hesitate to give actual application advice online.

 

[Euphylliaphyle]

<RANT>One would think that UPS makers would offer a GFI/AFI solution for their particular product as an accessory if not already built-in. Not doing so leaves the consumer to potentially spend $thousands for professional help to protect themselves from a $hundreds piece of hardware.</RANT>

 

[Reefering1]

It all depends on the specific UPS topology. I would hesitate to give actual application advice online.

What might one look for,if planning to do something like this with a ups unit/ inverter? Would a schematic clarify these differences between units?

 

[BeanAnimal]

<RANT>One would think that UPS makers would offer a GFI/AFI solution for their particular product as an accessory if not already built-in. Not doing so leaves the consumer to potentially spend $thousands for professional help to protect themselves from a $hundreds piece of hardware.</RANT>

It is not that easy. The output is floating -- there is no easy way to bond it to earth without creating all kinds of other issues that are worse the the issue you are trying to solve.

 

[Euphylliaphyle]

It is not that easy. The output is floating -- there is no easy way to bond it to earth without creating all kind of other issues that are worse the the issue you are trying to solve.

I will take your word for it. I got lost around the time the whole UPS topic came up! Thanks.

 

[BeanAnimal]

What might one look for,if planning to do something like this with a ups unit/ inverter? Would a schematic clarify these differences between units?

In general:

A generator or UPS output can only be bonded if the unit is listed for it. The transfer switch would isolate the utility neutral and connect the neutral from the generator/UPS instead. The existing service bond stays where it is and the transfer switch just selects which hot and neutral feed the loads.

 

[RobertK]

If you have a ground probe plugged into a GFCI outlet, and the GFCI outlet trips off, is the ground probe still grounded?

 

[Reefering1]

If you have a ground probe plugged into a GFCI outlet, and the GFCI outlet trips off, is the ground probe still grounded?

Yes

 

[Paul B]

But back to the "in theory" part, as depending on how the device is built, there could be enough leakage current for it to trip.

Hey Bean. Thats what I said but you said it so much more eloquently and used a lot more ink.

If you have a ground probe plugged into a GFCI outlet, and the GFCI outlet trips off, is the ground probe still grounded?

It depends on whether the GFI itself is grounded. If it is on a 2 wire system, with no ground, then no, it is not grounded. But I'm sure Bean could add a lot to that.

 

[blackgate]

So, I just double checked everything before I made any additional purchases and wanted to get an opinion on next course of action. In the electrical panel, tank is on a standard 20 amp breaker not an arc fault. The main tank outlets are not gfci and the tank itself is hooked up to a bluetti elite V2 UPS (we live in the mountains with very frequent power outages). I know I’m living very dangerously with my current setup and I do have some electrical know how, but what should I do next?

 

[blackgate]

Was thinking about grabbing the gfci extension between the tank and the UPS, but after reading the last couple posts, not sure if the cord would trip due to the bluetti electrical configuration (if I understood what @BeanAnimal was saying correctly)

 

[Freenow54]

So, I just double checked everything before I made any additional purchases and wanted to get an opinion on next course of action. In the electrical panel, tank is on a standard 20 amp breaker not an arc fault. The main tank outlets are not gfci and the tank itself is hooked up to a bluetti elite V2 UPS (we live in the mountains with very frequent power outages). I know I’m living very dangerously with my current setup and I do have some electrical know how, but what should I do next?

Just Questions Not an Electrician . Is it a dedicated circuit ? If so would 20 amp be too high ? Check out combo arc and GFI breakers for the panel and for equipment ie no drip legs on cords that can cause fires from water on the said power bar

 

[blackgate]

I keep apex and eb832s away from tank but the 20 amp breaker is not dedicated just to tank, but that is what the basement circuit is on. I’ve definitely used 15 amp drop cords on 20 amp breakers before?