Electrical safety and battery backups

[Kooma]

I have some questions and am interested in your feedback. I have always ran a UPS on my tanks for my pumps, skimmer and usually a heater. The UPS has always been hooked up to a GFCI, but the presence of the UPS has me wondering if I am undoing the safety of the GFCI with my UPS.

I was recently reading the thread about Miami Reef, and it had me wondering.

With a GFCI and grounding probe, am I safe?

I have a GFCI, and UPS plugged into it. Grounding probe is in the back of the UPS, or should it be in the GFCI?

If the GFCI pops, is the UPS not still a danger?

 

[Rocks reef]

Having the UPS plugged into a GFCI is good. If anything happens in front of the outlet, it will trip and turn off power leaving the UPS to do it's thing.
You can ground the UPS and the GFCI for redundancy, yes.

 

[Kooma]

My concern though is that if the UPS is feeding a pump, even with the GFCI tripped I still have 120v in the water if that pump is faulty, no?

 

[W31Olds]

From what I understand GFCI protected outlets and UPS Systems do not play well together. I would be concerned about a nuisance trip while you were away and the UPS backup power running out. And yes, you would still have a voltage present in the water. If it was a true short, as an example the AC pump winding shorted, the UPS breaker would trip. Leakage through a cracked housing is a little more tricky as it is not a direct short so some potential could be present in the water. I would ask you this. What is the purpose of your UPS? Have you ever tested how long it can run your tank? I purchased many of these for work and the Batteries never last very long after being in service. When my power goes out it's usually many hours to days and an UPS is virtually useless. I would have to spend thousands on a system for it to be truly effective. Sure, I could buy an hour or 2 with a low-cost unit, but my Tank would be fine with the absence of power for an hour or two and I'd still have to hook up my generator.

 

[jsmkmavity]

I have built my own back-up power with a sealed battery in a box and wired thru a relay and a gfci receptacle that is powered by an inverter connected to the battery so line power and back-up power both have gfci protection. I dont know the internals of the ups you are using but i would think you could plug a gfci into the ups and then plug your back-up pump into the gfci? The power is physically seperated in my setup or a ups so the gfci's wont fight each other, although i am not sure its possible they could fight anyway.

 

[Kooma]

From what I understand GFCI protected outlets and UPS Systems do not play well together. I would be concerned about a nuisance trip while you were away and the UPS backup power running out. And yes, you would still have a voltage present in the water. If it was a true short, as an example the AC pump winding shorted, the UPS breaker would trip. Leakage through a cracked housing is a little more tricky as it is not a direct short so some potential could be present in the water. I would ask you this. What is the purpose of your UPS? Have you ever tested how long it can run your tank? I purchased many of these for work and the Batteries never last very long after being in service. When my power goes out it's usually many hours to days and an UPS is virtually useless. I would have to spend thousands on a system for it to be truly effective. Sure, I could buy an hour or 2 with a low-cost unit, but my Tank would be fine with the absence of power for an hour or two and I'd still have to hook up my generator.

The UPS on the tank gives me 2 hours of run time, when away from home for the day at work, that’s 2 hours before the tanks condition starts to deteriorate.

I’ll have to speak with a local electrician and see what is the best way to ensure it is safe.

I run a rack mount APC smart-ups 1500VA unit on each system.

 

[jsmkmavity]

@BeanAnimal would probably be familiar with the internal schematic/electronics of many UPS and let us know if there is a conflict i am unaware of.

 

[W31Olds]

Kooma, if you haven't already checked them for run time, I would. I used many APC units and the batteries lose capacity after being in service for a while never giving the stated run time. I actually advised Miami Reef (RIP) when he was having problems with House Power Breaker box issues and the GFCI issues with his Tank. I considered him a friend and expert Reefer with an impressive Tank, however to my knowledge the details this Tragic Accident were never really explained. I was concerned about the condition of the outside Breaker Panel and the circuit breaker trips he was getting during strong storms

 

[BeanAnimal]

@BeanAnimal would probably be familiar with the internal schematic/electronics of many UPS and let us know if there is a conflict i am unaware of.

Any UL Listed home UPS built after November 17th 2000 (and many/most built prior) will have a floating neutral output. This means that it is not referenced to the home's neutral and or bonded ground. This is per UL 1778



A SmartUPS (line interactive) breaks both the Line and Neutral conductors when on battery.

The following image is example readings taken while the unit is outputting utility power.

The following image is the same UPS output running on battery

Notice that now both LINE and NEUTRAL show voltage to earth, less than 120. We don't know the current however. But we can't be sure that the current will or will not be read by a downstream GFCI as fault current or meet the threshold to trip.

These photos and further explanation are here

Why can I measure voltage between the ground and neutral wires when my UPS is on battery? | Schneider Electric USA

www.se.com

So, in general
A GCI on the INPUT side may trip if there is a fault on the output side, but the UPS will then simply revert to battery ad re-energize the fault!

A GFCI on the OUTPUT side may or may not trip if there is a fault on the output side. It may or may not nuisance trip depending on the specifics of the output.

So in general GFCIs should not be seen as protecting the output of a UPS. Many if you using UPS systems have GFCI circuits or breakers. That is fine. The GFCI does protect between the GFCI and the UPS input. Otherwise, if it trips or nuisance trips it will cause the UPS to behave the same as it would in a power outage. Just be aware that if it is a true FAULT trip, that the fault will be re-energized when the UPS is on battery. This may or may not present the same danger with the floating neutral.

Sorry - but I can't really add much more. There are a lot of variables to account for.

 

[Kooma]

Any UL Listed home UPS built after November 17th 2000 (and many/most built prior) will have a floating neutral output. This means that it is not referenced to the home's neutral and or bonded ground. This is per UL 1778



A SmartUPS (line interactive) breaks both the Line and Neutral conductors when on battery.

The following image is example readings taken while the unit is outputting utility power.

The following image is the same UPS output running on battery

Notice that now both LINE and NEUTRAL show voltage to earth, less than 120. We don't know the current however. But we can't be sure that the current will or will not be read by a downstream GFCI as fault current or meet the threshold to trip.

These photos and further explanation are here

Why can I measure voltage between the ground and neutral wires when my UPS is on battery? | Schneider Electric USA

www.se.com

So, in general
A GCI on the INPUT side may trip if there is a fault on the output side, but the UPS will then simply revert to battery ad re-energize the fault!

A GFCI on the OUTPUT side may or may not trip if there is a fault on the output side. It may or may not nuisance trip depending on the specifics of the output.

So in general GFCIs should not be seen as protecting the output of a UPS. Many if you using UPS systems have GFCI circuits or breakers. That is fine. The GFCI does protect between the GFCI and the UPS input. Otherwise, if it trips or nuisance trips it will cause the UPS to behave the same as it would in a power outage. Just be aware that if it is a true FAULT trip, that the fault will be re-energized when the UPS is on battery. This may or may not present the same danger with the floating neutral.

Sorry - but I can't really add much more. There are a lot of variables to account for.

That’s great information.

Presently I have a GFCI outlet and the UPS is connected to this outlet. I have my apex power bar plugged into the back of the UPS.

It’s sounding like this type of UPS is not a good idea to have in line with the power from the wall.

The next question becomes, how do we make it safe while having backup power?

 

[W31Olds]

I am considering a Whole House Generator. That solves 3 problems. The safety issues you're posting about, the pain of hooking up a portable Generator, and a power failure when on travel or vacation. Plus, keeps your Furnace/AC on and your Refrigerators running. If that's not an option, just keep the UPS and don't sweat it, but establish an Equipment Safety Maintenance routine. I have a pretty basic setup but would inspect my pump housings, cords, Heater seals/cords, and inspect/replace UV O-rings. Use DC pumps and titanium heaters. Don't forget all the other equipment you use for say salt mixing, water changes, etc.

 

[BeanAnimal]

That’s great information.

Presently I have a GFCI outlet and the UPS is connected to this outlet. I have my apex power bar plugged into the back of the UPS.

It’s sounding like this type of UPS is not a good idea to have in line with the power from the wall.

The next question becomes, how do we make it safe while having backup power?

The setup is fairly standard. The floating neutral still poses the same LINE to NEUTRAL danger as any 120 V source. The LINE to GROUND (ground fault) danger is different and theoretically much smaller because the NEUTRAL is not bonded to ground. So the "fault" that may trip the upstream GFCI and force the UPS to battery may not be a "fault" on battery. So, I would not say it is a "bad idea" to use a UPS downstream of a GFCI, but rather it is important to understand that there is no GFCI protection on battery, even if the risk of a dangerous ground fault is also theoretically much lower when on a battery.

 

[DexterKarin]

Okay, I'm way out of my league, but I have a GFCI power strip, plugged into battery which is then plugged into GFCI outlet. This power strip has heater, return pump and ato. Does that answer question of safety at all?

 

[BeanAnimal]

Okay, I'm way out of my league, but I have a GFCI power strip, plugged into battery which is then plugged into GFCI outlet. This power strip has heater, return pump and ato. Does that answer question of safety at all?

On mains power you have two GFCIs in series. That can create odd behavior in some cases, but is not a safety concern. On battery you have a GFCI after the UPS, but. because the NEUTRAL is floating, the GFCI maya not be able to detect a fault. It does not create a danger, but it does not work as you would expect, if at all.

 

[jsmkmavity]

With as much money as many spend on a UPS and still have little or no protection from ground fault during power outage i would think only plugging in a new unused standby pump and heater into the UPS would be a good and affordable option. That way if it was an actual ground fault that caused the trip on the utility power the culprit would not be powered from the UPS power. At some point the complexity and cost will rise enough to make a standby generator a viable option. It is likely directly related to the size of the reef tank a person has due to the increase of equipment size/load as tank size/volume increases and how much needs to operate during a power outage. If the problem were actually a ground fault you would still be protected on backup generator power since the generator power is applied upstream of the various gfci devices, and then you would know to go looking for cause of the fault.