Compliant way to put entire circuit on battery backup?

[anythingyoucanimagine]

Please forgive my ignorance. This is where my lack of NEC knowledge shows.

I have 120/240V residential split phase. I'm in the middle of a whole-home rewire (ahj has adopted 2017). I've got a brand new 200 amp square-d panel but not much more than that.

I'd like to run a short section of 10/3 from a 30A breaker to an L14-30 mounted on my panel's backer-board.

From there I would like to plug in an appropriately sized (for 30 amps) APC branded, listed, etc. battery backup unit (bbu).

I would then like to plug in one 5-20P and run a short section of 12ga soow to an outlet box with a receptacle on same backer-board next to panel. (this is where the g/a/combo protection will be) I then want to come out of that outlet box with 12/2 nm-b and continue the circuit into the house.

The battery unit is listed and internally fused to supply either 20A or 15A circuits (or a combination thereof as specified by manufacturer).

This is for a 20A branch circuit that supplies our internet/data/telco stuff. I know the inspector isn't going to have a clue about any of this... which is why I'm asking so I can have code rules/numbers to back all this up.

This is what I don't know:
The bbu has three 5-15r, two 5-20r and one 10-20r. I can (mechanically with internal disconnect switching) disable all but one 5-20R --but technically the device could supply more than just the one 5-20r. Is that OK?

I don't know about g/a/combo protection. I know twist lock doesn't need to be tamper resistant but can bring 30A with no g/a/combo protection out of a panel (in an attached garage) and run it to a twist lock receptacle next to panel? Do I need the 30A breaker to have any g/a/combo protection?

From there can I plug in an internally fused device that is listed and capable of stepping down to and supplying 120V at either 15A or 20A? I have not found anything in the nec that says I cannot --but I'm pretty sure inspector is going to have a field day with this. One dedicated receptacle, one device (with no g/a/combo protection)... Is that technically a branch circuit yet?

I believe I'm fine switching between nm-b and soow?? (as long as correct size, connectors, etc.)

Physical location: Unconditioned garage. Semi-conditioned, it won't get below 50-55F and humidifier/dehumidifier for moisture control. Battery will be up over 8-feet, I pulled a permit to change over two rafter ties to joists to support the ~300 pound load. Battery will be bolted to a support base built into the garage ceiling joists. All of this will be within a 6-foot radius of the panel.


Thanks. I think I provided enough info. Happy to give more info if I wasn't clear enough. Garage Journal has been an amazing resource. Thanks again.

 

[rlitman]

My understanding is that you cannot transition to SOOW with a plug on it plugged into the UPS, used to supply a circuit in your house.

But, there is a compliant way to do this. On an APC unit of this size, there is usually a knockout on the rear where you can hard wire the output. From there, you can hard wire the unprotected UPS output to a new subpanel, and run circuits from that however you like. Plus you'll still have the convenience outlets directly on the UPS available.

Be sure to get a UPS unit with a bypass.

The bigger concern I'd have would be with heat. UPS battery lifetimes are greatly reduced when exposed to heat. Unconditioned spaces will halve their already short lives at best. At worst, in a hot attic space, batteries could be destroyed in just a month or so.

Also, keep in mind the fire risk. Particularly in hot spaces, there is the potential for a fire during a charge cycle (look up battery thermal runaway). In the very least, be sure you have good sheetrock above and around your UPS area. Something that slows the spread of fire.

 

[anythingyoucanimagine]

My understanding...

Thank you for that. Very much appreciated. Usually the NEC is easy. My gut said that a few things about my plan sounded sketchy and not compliant. Thank you again. Yes there are a few knockouts. I didn't even think about them --usually everything I do with batteries like this is inside a rack/cabinets in secure facilities.

I already own the bbu (legit UPS). I took it out of a client site and was able to get replacement batteries for the right price... (My Dell guy hooked me up)

Yes it has a bypass, yes I'm worried about battery life, no --I had never considered fire. This is the first unit I've really owned/managed that is out of warranty. Thank you again.

I've been looking at mini-splits for the garage space. Still won't bring it down to datacenter hot/cold isle temps but but it would be a lot better. Garage will be --once I pass rough inspection 5/8 drywall in entire space. Do you think I should double the 5/8 around the UPS? I'm fine doing whatever but also don't want to impede air flow/create an oven...

I have a DR site in Garden City, racks at 33 Whitehall, 32 AofA, NY1, NY4 and one up in CT. I'm fine dealing with all this stuff inside a secure facility but I've never put a battery like this inside a house. (our vacation house/cabin) I'm shocked I found a split phase battery this big. Everything I usually do is 208Y. I've got piles of 208Y batteries and PDU's at home... (hope you know what I mean --the battery cells are not 208Y, the housings/contraptions that hold the batteries accept 208Y power in and play nice with battery cells)

If the grid could supply 48VDC my life would be so much easier...

 

[rlitman]

208Y PDUs. Sounds like you're using Hubbel CS8364. Yeah, I've got a lot of those.

Now you've got me wondering why you're spread out all over facilities like that (I get that the network access in NY1 is fantastic, but the facility is a shithole; NY4 is in a flood zone ...) , but that's a different conversation that I'd love to have with you (I'm actually considering moving some equipment that's in NJ1).

You certainly don't want to stuff a UPS into an unvented closet or impede its airflow. Maybe you could duct airflow through fire damper louvers with a fusible link.

What model APC did you get? Many require conversion (moving around some wires inside) from 208 input to go to a 240 supply.

 

[theoldwizard1]

I hope you have not already purchased that APC bbu and are expecting more than it can deliver Those are typically designed to run for less than 15 minutes and then shut themselves off.

 

[dogdog]

I hope you have not already purchased that APC bbu and are expecting more than it can deliver Those are typically designed to run for less than 15 minutes and then shut themselves off.

No, the ones he is mentioning are probably at price tag of $20K when new data center stuff... those are design to run for at least an hour or more... I have about 5 older ones super heavy sitting around without batteries (8U size or 10...).... Mine was used in a command center to power a PC for 3 hours... till they decommission the command center.. pretty sure the OP's one is similar .....If OP haven't acquire those, he would have better off getting those GoalZero stuff... for small cabins...

 

[wyliesdiesels]

Please forgive my ignorance. This is where my lack of NEC knowledge shows.

I have 120/240V residential split phase. I'm in the middle of a whole-home rewire (ahj has adopted 2017). I've got a brand new 200 amp square-d panel but not much more than that.

I'd like to run a short section of 10/3 from a 30A breaker to an L14-30 mounted on my panel's backer-board.

From there I would like to plug in an appropriately sized (for 30 amps) APC branded, listed, etc. battery backup unit (bbu).

I would then like to plug in one 5-20P and run a short section of 12ga soow to an outlet box with a receptacle on same backer-board next to panel. (this is where the g/a/combo protection will be) I then want to come out of that outlet box with 12/2 nm-b and continue the circuit into the house.

The battery unit is listed and internally fused to supply either 20A or 15A circuits (or a combination thereof as specified by manufacturer).

This is for a 20A branch circuit that supplies our internet/data/telco stuff. I know the inspector isn't going to have a clue about any of this... which is why I'm asking so I can have code rules/numbers to back all this up.

This is what I don't know:
The bbu has three 5-15r, two 5-20r and one 10-20r. I can (mechanically with internal disconnect switching) disable all but one 5-20R --but technically the device could supply more than just the one 5-20r. Is that OK?

I don't know about g/a/combo protection. I know twist lock doesn't need to be tamper resistant but can bring 30A with no g/a/combo protection out of a panel (in an attached garage) and run it to a twist lock receptacle next to panel? Do I need the 30A breaker to have any g/a/combo protection?

From there can I plug in an internally fused device that is listed and capable of stepping down to and supplying 120V at either 15A or 20A? I have not found anything in the nec that says I cannot --but I'm pretty sure inspector is going to have a field day with this. One dedicated receptacle, one device (with no g/a/combo protection)... Is that technically a branch circuit yet?

I believe I'm fine switching between nm-b and soow?? (as long as correct size, connectors, etc.)

Physical location: Unconditioned garage. Semi-conditioned, it won't get below 50-55F and humidifier/dehumidifier for moisture control. Battery will be up over 8-feet, I pulled a permit to change over two rafter ties to joists to support the ~300 pound load. Battery will be bolted to a support base built into the garage ceiling joists. All of this will be within a 6-foot radius of the panel.


Thanks. I think I provided enough info. Happy to give more info if I wasn't clear enough. Garage Journal has been an amazing resource. Thanks again.

Are you sure its a 10-20r? That would be a 120v/240v NON-grounded 20a outlet.

As to how to wire this, i would definitely hardwire it.

Also, make sure your install complies with the applicable NEC articles including 645 and 700, namely 645.11 and 700.12. There is a good amount to read there...

 

[anythingyoucanimagine]

208Y PDUs. Sounds like you're using Hubbel CS8364. Yeah, I've got a lot of those.

Now you've got me wondering why you're spread out all over facilities like that (I get that the network access in NY1 is fantastic, but the facility is a shithole; NY4 is in a flood zone ...) , but that's a different conversation that I'd love to have with you (I'm actually considering moving some equipment that's in NJ1).

You certainly don't want to stuff a UPS into an unvented closet or impede its airflow. Maybe you could duct airflow through fire damper louvers with a fusible link.

What model APC did you get? Many require conversion (moving around some wires inside) from 208 input to go to a 240 supply.

Sandy was fun... I lost a few racks in lower manhattan. (ghetto basement stuff) A lot of what I host is sponsored access (nyse) and siac (consolidated tape) stuff. Depending on who is doing what, they don't have a choice where they go (latency, security or both). Yes --I 100% agree that ny1 is an absolute shithole.

I sublet half racks at 32AofA and 33 Whitehall mostly just to satisfy idiot clients so they can say they "have servers in NYC". Garden City DR is a client's DR and I piggyback with them. The CT stuff is also an idiot client who can't do math --they don't understand that the matching engines are all in NJ and by paying x dollars a month more (per U) to get into a colo DC with their introducing broker... I could save them orders of magnitude over the rack they currently have. You are preaching to the choir. I've been hammering them for years. It's a pain in the *** to be spread out like that.

I forgot --I'll edit and update with model numbers but have to warn you, stuff I'm trying to use is not new...

I hope you have not already purchased that APC bbu and are expecting more than it can deliver Those are typically designed to run for less than 15 minutes and then shut themselves off.

I didn't purchase. I acquired for free With the load I'll put on this circuit, everything will stay up for probably about 45-55 minutes. Maybe an hour-1:15 at best. All I want is 4-5 minutes so auto tx switch and generator can kick on.

No, the ones he is mentioning are probably at price tag of $20K when new data center stuff... those are design to run for at least an hour or more... I have about 5 older ones super heavy sitting around without batteries (8U size or 10...).... Mine was used in a command center to power a PC for 3 hours... till they decommission the command center.. pretty sure the OP's one is similar .....If OP haven't acquire those, he would have better off getting those GoalZero stuff... for small cabins...

Yes this is 10U. Was free so have already "purchased" it. Yes there are better alternatives --but not free.

Are you sure its a 10-20r? That would be a 120v/240v NON-grounded 20a outlet.

As to how to wire this, i would definitely hardwire it.

Also, make sure your install complies with the applicable NEC articles including 645 and 700, namely 645.11 and 700.12. There is a good amount to read there...

Thanks for the code references. I will start reading. Yes, I meant 10-20r. This is an older unit and the 10-20r was meant to piggyback or daisy chain manufacturer's units. If you use the 10-20r it "knows" and the 5-15r and 5-20r receptacles don't work. All this stuff is grounded back to the server rack (I guess how you use metal conduit as ground). All devices in the rack are grounded back to the rack through the rack ears/bolts --and the way this system was designed, the piggyback device or networked PDU (power distribution unit --fancy power strip) would also be grounded back to the rack chassis. If I had to guess, it was the manufacturer trying to be slick and make something "proprietary" and it was a total fail... but idk --yes, non-grounded. Again, thanks for the code references.

 

[rlitman]

Are you sure its a 10-20r? That would be a 120v/240v NON-grounded 20a outlet.

As to how to wire this, i would definitely hardwire it.

Also, make sure your install complies with the applicable NEC articles including 645 and 700, namely 645.11 and 700.12. There is a good amount to read there...

Huh? 700.12 is mainly for emergency and legally required systems. Since his loads are purely "optional", it doesn't apply. 645.11 is a trickier one. That is a specific requirement for EPO in ITE rooms, but the devil in the details is that it only applies where hard wired flexible power whips are employed (as this is a specific exception for ITE rooms). Since he's hard wiring the UPS to fixed outlets, it too does not apply.

Sandy was fun... I lost a few racks in lower manhattan. (ghetto basement stuff) A lot of what I host is sponsored access (nyse) and siac (consolidated tape) stuff. Depending on who is doing what, they don't have a choice where they go (latency, security or both). Yes --I 100% agree that ny1 is an absolute shithole.

I sublet half racks at 32AofA and 33 Whitehall mostly just to satisfy idiot clients so they can say they "have servers in NYC". Garden City DR is a client's DR and I piggyback with them. The CT stuff is also an idiot client who can't do math --they don't understand that the matching engines are all in NJ and by paying x dollars a month more (per U) to get into a colo DC with their introducing broker... I could save them orders of magnitude over the rack they currently have. You are preaching to the choir. I've been hammering them for years. It's a pain in the *** to be spread out like that.

I forgot --I'll edit and update with model numbers but have to warn you, stuff I'm trying to use is not new...

I didn't purchase. I acquired for free With the load I'll put on this circuit, everything will stay up for probably about 45-55 minutes. Maybe an hour-1:15 at best. All I want is 4-5 minutes so auto tx switch and generator can kick on.

Yes this is 10U. Was free so have already "purchased" it. Yes there are better alternatives --but not free...

Yeah, that makes plenty of sense. You really should check out NJ1. They're a 30 minute drive from NY1, there's plenty of fiber between the two, and the facility is truly first rate. It's a night and day difference. I find it really a shame, because whoever had the idea to buy out an abandoned Macy's and turn it into a data hotel was a GENIUS, but the actual engineering and execution of NY1 is a MEGA fail (not to mention the neighborhood, but I can look past that). The lost potential is just maddening.

I can't say I've been to 32AofA, but I've been through the AT&T nuclear hardened building in Midtown at 811 10th. That's some place, as is the Verizon building. I've had stuff located in 33 Whitehall and 75 Broad over the years, but because of my Long Island presence, I've always tried to have my DR in NJ, as the city was just too close for comfort, with too few fiber routes out (the fact that it's an actual island and all...).

It sounds a little to me like you've got a version of a Symmetra RM. My only concern is that Symmetra series UPS are online, so the power efficiency is lower than a standby unit. It's potentially better for your equipment, but costs you more in electricity. However, if you're using it for business, then that may be a sensible write off...

And I completely understand where you're going. I've got an APC Matrix 5000 that powers outlets throughout my house. In my case, it's to keep my Tivos, televisions and computers working, plus an outlet for my CPAP. My generator is on a manual switch, and having a few hours of silent power is nice.

 

[anythingyoucanimagine]

And I completely understand where you're going. I've got an APC Matrix 5000 that powers outlets throughout my house. In my case, it's to keep my Tivos, televisions and computers working, plus an outlet for my CPAP. My generator is on a manual switch, and having a few hours of silent power is nice.

I used to have all my non-nyse stuff in 111 8th. Until Google. That was awesome. 20 minute walk from my apartment (5-minute Vespa ride), easy, close, cheap, manageable... Thanks Google.

32AofA isn't terrible. Pretty similar to the vzn building. Not quite as nice as 33 Whitehall but they keep it halfway decent. Honestly I think a lot of it has to do with the management more than the facility. You can keep a dump clean & orderly and make it halfway decent --or you can easily trash a pristine facility and make it ****.

I've heard about the ATT building but never been inside. I've been inside a bunch of other very secure facilities so I imagine it must be pretty cool. Maybe someday...

I thought long & hard about putting my DR stuff out in garden city... LI is an island too... That's partially why I don't force my CT guys down to NJ. It's nice to have something off-island --seriously the Tri-state area scares the **** out of me. I know too much and holy **** is it a target/bullseye. Garden city is just far enough outside of the required radius (for compliance) that they can use it as DR (and employees/owner of company lives out there). I have two (old 25U PowerEdge) racks in my home 4-5 hours north of ny1/4 --that's my real "oh ****" DR. We got super lucky and live in a neighborhood with residential 208Y so my home racks are my business writeoff. We just bought a ~1200sq/ft ski/vacation cabin (in need of a total gut/reno and will probably be 2000sq/ft by the time she's done) up in VT. This home-UPS thing is mostly fun/play and my personal DR. But with 16tb drives who knows...

Christ... Do you know how much I paid to modify a Backblaze 4u storage chassis to accept 16-port backplanes and 48x 2tb drives... (stock is 45) That was not even 10 years ago!

Yes this is an older symmetra. Yes it's always on and yes at a cost. At home in addition to the 208 Wye we have panels on the roof. The ski house needs a roof. When I deal with that this spring I'm already looking at a few panels for up there. (actually want to research stand-alone supports/towers. I've been reading about fire departments having issues venting roofs during house fires due to panels on the roof...) But panels in some form will happen soon. Probably not whole-house but enough that the energy bill is $0 when we aren't there. (and to offset stupid stuff like the electric tile-warming floors she wants... pretty much everywhere there is tile)

This one 20A circuit will have (connected/wired) smokes, house alarm, TV's, ONT box, firewall, switch & AP's (Ubiquiti PoE stuff)... That's pretty much it. Generator is auto-start, auto tx so it'll only need 60-seconds --maybe 90 seconds at most. Once I get a few panels on the roof (and more batteries) the only time the generator should turn on is once a month for maintenance check.

75 Broad... LOL... don't get me started on that place Do you know Mike from Suspenders (the bar) by chance? He worked in the adult film industry long enough ago that it was actually film. Back in the 80's when stuff in NYC was dirt cheap he bought a building with a (ghetto --ask him to show you pictures, he's got a 3-ring binder behind the bar --it was ghetto) datacenter down in the basement. (right near 75 broad) He bought it to host ****. Today he's 65yo --ehhh... Maybe 70-75yo and he owns 5 (somewhat bottom tier) data buildings in lower Manhattan. All from ****. He doesn't do the adult stuff anymore (but he threw me one hell of a bachelor party). I should clarify --he is no longer an actor but he does have many clients that host god only knows what. Most of the chop-shop day-trading firms also run their garbage through his rack space. I get a lot of my clients from him. If they are legit (meaning 100% legal, above board, not doing anything shady, etc.) and they need better SLA/connectivity/service then I'm one of the guys Mike sends people to. I turn away more than I take. Don't want to jinx it but I've got a pretty good thing going --this Democrat tax on Wall Street transactions would absolutely F me and shut me down.


Getting back to my original question: the only real issue with my initial layout was the physical plug? Hardwiring that setup is fine? Thanks!

 

[theoldwizard1]

I'd like to run a short section of 10/3 from a 30A breaker to an L14-30 mounted on my panel's backer-board.

From there I would like to plug in an appropriately sized (for 30 amps) APC branded, listed, etc. battery backup unit (bbu).

I would then like to plug in one 5-20P and run a short section of 12ga soow to an outlet box with a receptacle on same backer-board next to panel. (this is where the g/a/combo protection will be) I then want to come out of that outlet box with 12/2 nm-b and continue the circuit into the house.

The battery unit is listed and internally fused to supply either 20A or 15A circuits (or a combination thereof as specified by manufacturer).

This is for a 20A branch circuit that supplies our internet/data/telco stuff. I know the inspector isn't going to have a clue about any of this... which is why I'm asking so I can have code rules/numbers to back all this up.

There is no way that they will allow you to "plug" an exiting in wall circuit to an outlet from that bbu !

If you by "g/a/combo" you mean generator/auto transfer switch then you have it in the wrong position. It needs to be "upstream" of the bbu.

• Run 10/3 to the box that hold the generator/auto transfer switch
• Attach your bbu here either with an appropriately sized plug or hard wire (either metallic or water tight) to the output of the generator/auto transfer switch

Likely you will have to pull a SEPARATE WIRE from the bbu to the server room and terminate it INSIDE the server rack(s), with labeling to indicate it is "HOT AT ALL TIMES". You will need some type of disconnect INSIDE the server rack(s) so that anyone working there can kill the power. All power distribution inside that cabinet MUST come from that disconnect.

Sorry I can not reference NEC sections, but look for "alternate power sources".

What is the model number of the bbu ?

 

[WaterBoyz]

My apologies.........

Since there is a discussion of Battery Back Up this reminded me what I have and had some plans to run my electronic stuff during power blips and outages.

I got this from a data center that closed. Have no idea much about it but I know it needs batteries. Can't even pick up the unit with the batteries installed. HEAVY HEAVY.

I had experience years ago with ONEAC units so have some knowledge. That being said, what do I actually have and can I use it as my home PC and related gear?

 

[rlitman]

My apologies.........

Since there is a discussion of Battery Back Up this reminded me what I have and had some plans to run my electronic stuff during power blips and outages.

I got this from a data center that closed. Have no idea much about it but I know it needs batteries. Can't even pick up the unit with the batteries installed. HEAVY HEAVY.

I had experience years ago with ONEAC units so have some knowledge. That being said, what do I actually have and can I use it as my home PC and related gear?

I believe that is an APC 2200 XL RM 5U. The plug is 120V. Yeah, you can use it on a home PC, but you'll need new batteries.

 

[u3b3rg33k]

my primary concern is your placement of the batteries high up in an unconditioned garage. you're basically guaranteeing them a short life due to heat. lead acid should be kept under 80F. I'd want the UPS in the room with the gear, personally. not in the garage.

 

[wyliesdiesels]

I believe that is an APC 2200 XL RM 5U. The plug is 120V. Yeah, you can use it on a home PC, but you'll need new batteries.

Except the m/n sticker says SU3000RMNET

 

[rlitman]

Except the m/n sticker says SU3000RMNET

Good point, I didn't see that. That has me more confused. It's an XL model, because it is a 5U and has an Anderson connector for an external battery.

 

[WaterBoyz]

Good point, I didn't see that. That has me more confused. It's an XL model, because it is a 5U and has an Anderson connector for an external battery.

So, if I really really really wanted a long battery up-time I could add another set?

What size circuit/circuit breaker do I need to feed this monster?

Any good source for batteries?

 

[rlitman]

The Anderson connector is to hook up to an APC battery pack made to match that unit. Yes, it is to extend runtime. Note here that XL models from APC not only have the Anderson connector, but they also have higher rated cooling capacity. That is, most smaller UPS units are designed with a short duty cycle, but that is naturally limited by the battery capacity. So, if you were to add external batteries to a typical small UPS with the hopes of extending run time, you will likely overheat the unit. On these XL models, that is not a problem, as they are designed to be able to run at 100% rated output for extended periods (since the external battery packs have their own Anderson logs so that they can be daisy chained).

Your UPS has a 120V input. Your plug APPEARS (the picture isn't clear to me) to be an L5-30, so that should go on a 30A breaker. But there's little reason you couldn't change it to a 5-15, and just plug it into the wall, IF your expected load will work on that little power.

I've had decent luck getting replacement SLA batteries at zbattery.com.

 

[u3b3rg33k]

the way I do UPSes is I pick up the cheapest APC unit that does 24V and meets the VA capacity I want, then buy two of the largest AGM batteries the farm store has, and put them in a trolling battery housing. costs me the same money as buying from APC, but they last years longer than the internal batteries. my last set got me 60+min runtime at 500W (long enough to drive home and start the generator) and lasted 8 years, with numerous near 100% DoD cycles.

don't forget an appropriate DC disconnect & fusing.

or you can spend IT budget money on new external batteries.

 

[theoldwizard1]

the way I do UPSes is I pick up the cheapest APC unit that does 24V and meets the VA capacity I want, then buy two of the largest AGM batteries the farm store has, and put them in a trolling battery housing. costs me the same money as buying from APC, but they last years longer than the internal batteries. my last set got me 60+min runtime at 500W (long enough to drive home and start the generator) and lasted 8 years, with numerous near 100% DoD cycles.

You have lived a charmed life or just have a really OLD APC ! The "modern" (?) ones will shut themselves down when trying to run them for more then 10-15 minutes of runtime either from overheating or a simple built in timer !

 

[u3b3rg33k]

I've had APC5000s run for an hour at work before battery exhaustion with few switches (2) switches on them.

We've since switched to the SRT series because standby UPS are for chumps. they're configured for maximum runtime, with no early shutdown. battery life is less important than uptime in my world. I assume you must be talking about the home grade units that lack adequate cooing fans?

BTW the SRT and RT series UPSes run the inverter 24/7, 365. At a glance they're basically a VFD with a fixed frequency output and batteries on the DC bus.

 

[nsula_country]

You have lived a charmed life or just have a really OLD APC ! The "modern" (?) ones will shut themselves down when trying to run them for more then 10-15 minutes of runtime either from overheating or a simple built in timer !

I use APC UPS units in PLC cabinets as backup power for critical PLC's.

a 1500va unit will run 16 watts for over 2 hours. They don't power off after 15 min...

CT