UPS and GFCI and Power Interruption

[DallasFish]

Hello All -

I wanted to share a recent experience with my 55g tank, APC UPS, and portable GFCI units.

First, the setup:

The APC UPS is plugged into a regular grounded wall outlet.

I have two GFCI plugs (see Amazon.com: TRC Shockshield White Portable GFCI Plug with Surge Protection 14650-021-012: Home Improvement) plugged into the UPS, one on the battery-backed-up side, one on the surge-only side.

My heater and lights plug into the non-battery side GFCI plug, and the air pump and filter plug into the battery side GFCI plug.

I had a brief power outage today and here is where I got my surprise. As soon as the power went out, both GFCI plugs tripped off, even before the UPS battery came online.

I did some digging, and found this article:

Ground Fault Circuit Interrupters (GFCI)

which points out that portable GFCIs (like the plugs I am using, or those on extension cords) are required by code to trip if the input power to them is interrupted, and have to be manually reset. This is to prevent, for example, a table saw from suddenly coming back on in a workshop after a power failure. But this is bad for the fish - it means the UPS battery can't drive the air and filter until somebody manually flips the GFCIs. Note that GCFI wall receptacles DO NOT have this requirement, and normally do not trip during a power failure.

It does no good to plug the UPS itself into a GFCI receptacle. If a short in the tank equipment trips the GFCI, the UPS says "o, power's off, turn the battery on", and WHAM the tank equipment is re-energized - a very dangerous condition.

So what I plan to do is to buy two GFCI wall receptacles, mount them in electrical boxes with short pigtail cords, and plug them into the UPS in place of the portable GFCIs. This should give me the GFCI protection without the manual reset when input power is lost.

[Kurt_Nelson]

A couple comments...

I run somewhat the same setup you describe - portable GFCI coming out of a battery backup. However, I've never had an issue with my Lowe's purchased portable GFCIs tripping when the power has gone out. I've had several occasions to "test" my setup and the battery backup kicks on just as it should - with the GFCIs staying "on". So I guess I question the article.

The other issue is that a battery backup running out of a GFCI in the wall can be a dangerous thing if the GFCI is trying to do its job. Say you have a current leak in the tank. You stick your hand in the tank and the GFCI cuts out like it's supposed to. The battery backup senses no power and kicks in like it's supposed to. And now whatever component was causing the issue is back "live" again - with no GFCI to kick out. That's the whole reason I have not only a GFCI at my wall, but ones plugged into the output of my battery backup. {Edit: Sorry... didn't read your original post fully and thought you were plugging the backup into a wall GFCI. }

Edit:

I just reread your link about GFCIs and I think you misunderstood something. It doesn't say that all GFCIs that meet code have to trip when the power goes out. It says...

It is worth noting that some GFCI devices require a manual reset if the power
supply TO the GFCI is stopped...

Portable GFCIs, such as on extension cords that comply with OSHA standards
require a manual reset after even a momentary power outage -- these cords
are usually the heavier cords that might be found on a construction sight or
at Home Depot. On a construction job site, this feature prevents your circular
saw, for example, from starting up accidentally when the power supply is
restored after an outage. If your aquarium filters, heaters, etc. are
connected downstream from such a GFCI extension cord, you will lose life.

Note that the poster says "some" GFCI devices require a manual reset. I'm guessing my GFCI isn't OSHA compliant and that's why it doesn't trip when the power goes out.

[DallasFish]

Kurt -

That's what I've discovered on further reading as well. Portable GFCIs _may_ require manual reset on power failure, or may not.

It looks like the ones I bought did require the manual reset. I've returned them and will use those that don't.

Mike

update: for those who are interested, here's an example:
http://www.towermfg.com/distribution.htm
those with an M in the model # require manual reset after input power is lost, those without continue automatically. We aquarium folks probably want the automatic ones.

[HoCkEyGmC]

wait, i dont get it, im going to get a gcfi but what shouldnt i do with it? help...

[DallasFish]

Originally Posted by HoCkEyGmC

wait, i dont get it, im going to get a gcfi but what shouldnt i do with it? help...

Hockey -

I agree, its confusing.

The question comes down to, when the power goes off, do you want the stuff you plug into the GPS to come back on automatically when the power comes back on, or do you want to have to reset the GFCI before it comes on. If you want it to happen automatically, you need to get an auto-reset GFCI.

The other thing to remember is, if you are going to use a UPS battery backup unit and use GFCI, make _sure_ you have a GFCI between the UPS and the tank equipment.

I hope that helps.

[HoCkEyGmC]

what is GPS and UPS? im a newbie to electronics...

[CaptainAhab]

Ground Fault Circuit Interrupt and Universal Power Supply. One makes sure you have power the other makes sure you don't

[gheitman]

To elaborate, a UPS (i.e. Uninterruptible Power Supply) contains one or more batteries that continually charge when on AC power. Your devices such as filters, lights, heaters, etc. are plugged into battery backed-up outlets (or outlets that just protect against power spikes). When power is lost even momentarily the UPS will immediately switch over to discharging the stored battery power as needed. When the power is restored the UPS will switch back to charging the batteries. For aquarium use it is important to get a UPS that will generate a sine wave output otherwise your motors in filters and air pumps won't run correctly. This makes UPS units suitable for aquariums more expensive than those commonly used for computers.

[DallasFish]

gheitman did an excellent job in describing the UPS.

The GFCI is a safety device that helps by cutting off the electrical current if your tank equipment developes a short (e.g., a frayed wire in the heater cord)

Normally if you're using both UPS and GFCI, it would go:

Wall Power -> UPS -> GFCI -> tank equipment

If you google for UPS or GFCI you'll find lots more information.

[HoCkEyGmC]

so do i need to get a UPS for safety?

[neilanh]

The UPS is to provide you a limited amount of battery power should your power ever go out. This is important to maintain flow in SW tanks. It's really for peace of mind, IMO. Some people on here have tons of money invested in their tanks, and something as simple as an extended power outage can ruin corals.

[HoCkEyGmC]

so its almost like a generator when the power goes out?

[gheitman]

Batteries can't run as long as a generator so it won't protect you against long-term power outages. You would not want to have unimportant items plugged into the battery-backed outlets so that the power from the UPS lasts as long as possible.

[DallasFish]

FYI, here is a photo of the UPS system I ended up putting together.