Cost Effective Way to Provide Emergency Backup for LED Lights?

C

cryptonenologist

Member
Location
San Juan Bautista, CA
Occupation
Engineer
I've got a cleanroom buildout with 224 50W surface mount LED panels that are fed by constant current drivers. I need 58 of them to have the 90 minute reserve power for egress lighting. We are running tight on budget so trying to find the most cost-effective option.

I've been looking for a emergency driver that can match the 50W 600mA output of the drivers I have and haven't found much. This isn't my area of expertise and I'm assuming a lower wattage would be fine(verified by the photometric modelling) but I'm having trouble finding a constant current emergency driver. If I did find something, these look to be $75 and up so that will run a minimum of $4k for the drivers.

My other idea was to provide UPS with 90 minute capacity. I hate to convert DC to AC to DC when I can avoid it, but if I can't find emergency drivers this is a simpler problem to solve. I'd need 3kVA of output, and about 5kWh of capacity to ensure the 90mins of runtime. My drivers can take up to 240v input so a 208v single phase unit would be ideal. Anyone sell something like this off the shelf? Goalzero has close to what I need but it really isn't intended for commercial and would be 120v. Looking at Eaton those are seriously pricy.

Final idea was to redo my photometric with bugeyes. I think I could get away with about 50 bugeyes and if I go with the cheap manual test ones they would be $44 each and I would need around 50 of them.

Any thoughts are appreciated.
 
cryptonenologist said:
My other idea was to provide UPS with 90 minute capacity. I hate to convert DC to AC to DC when I can avoid it, but if I can't find emergency drivers this is a simpler problem to solve. I'd need 3kVA of output, and about 5kWh of capacity to ensure the 90mins of runtime. My drivers can take up to 240v input so a 208v single phase unit would be ideal. Anyone sell something like this off the shelf? Goalzero has close to what I need but it really isn't intended for commercial and would be 120v. Looking at Eaton those are seriously pricy.
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3kVA is where 120v UPS systems top out, while it's the beginning of the 208v units. Either way, despite the conversion losses involved, this would almost certainly be the easiest solution. Since you're dealing with LED drivers, though, I would suggest a unit advertised as "online" or "double-conversion." There are a ton of mfrs out there besides Eaton (APC, Vertiv, and Tripp-Lite are the names you've most likely heard, but they're not the only ones), so shop around ;)

cryptonenologist said:
Final idea was to redo my photometric with bugeyes. I think I could get away with about 50 bugeyes and if I go with the cheap manual test ones they would be $44 each and I would need around 50 of them.
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Never frown upon cheap and simple, just because it's cheap and simple ;) Just remember that if you choose this route, that routine testing and replacement of the batteries needs to be accounted for in some manner (not that this isn't also true of the UPS-based system, there's just a lot more of them to keep track of).
 
Thanks for the insight. Because double converting units are locked to the input phase, would it work to connect two UPS to one phase and neutral each and then use the two output hots to drive my load? In my research two 120v units ends up at half the price of a single 208v unit.
 
No... it's true they're locked to the input phase, but they're not locked to each other. Once the power goes out, they'll start drifting in relation to each other and the results will be unpredictable. If a pair of 3kVA 120V units are the solution you choose, split your lighting loads in half as well.
 
Very true.

Ultimately, I'm not finding any UPS options that have the output I need for much less than $10k, so unless someone chimes in with something cheaper they've seen, doing the bugeyes saves a significant amount of cash up front.
 
winnie said:
Why do you need all of the lights on a single UPS?
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Most vendors don't have online pricing for increased reserve capacity beyond the standard 3-10 minutes. The one I found that offers several options online, I'm not seeing any cost savings from using multiple UPS instead of one. Their 208V 3kVA unit that can have added capacity to hit 5.8kWh, which would be $10.7k. Getting 3x 1kVA with batteries up to 2kWh each would run $13.5k. The 120V units aren't any cheaper.
 
Knightryder12 said:
Why not a lighting inverter?
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hbiss said:
I was thinking the same thing the other day then I forgot about this thread. Don't know pricing but these things are made for emergency lighting. 90 min runtime is standard with up to 120 optional.

https://www.lightinginvertersupply.com/product/power-wave-1

-Hal
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This is worth looking into. I sometimes tell people that experience in the engineering and construction fields is partly just about knowing what the right term for the thing you need is. Even just knowing about software. I looked for years for an easy way to quickly markup CAD when someone casually mentioned BlueBeam to me.

I found some available online here https://www.exitsignwarehouse.com/c...ency-power-750-to-1150?variant=40247017734226

This would cost around $8k for the amount of power I need so not insignificant. And inspector will probably be happier with this since it is labeled with UL924.
 
cryptonenologist said:
This is worth looking into. I sometimes tell people that experience in the engineering and construction fields is partly just about knowing what the right term for the thing you need is. Even just knowing about software. I looked for years for an easy way to quickly markup CAD when someone casually mentioned BlueBeam to me.

I found some available online here https://www.exitsignwarehouse.com/c...ency-power-750-to-1150?variant=40247017734226

This would cost around $8k for the amount of power I need so not insignificant. And inspector will probably be happier with this since it is labeled with UL924.
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Your lighting rep (if you are using one) should have lighting inverters as one of his companies that he or she reps, ask them. They will also be able to help you size it properly.
 
I've been down the lighting inverter route - it's always been a problem. The inverter is going to be the LEAST reliable thing in the system, so if you really have to have lighting, you'd need two inverters. With an inverter, everything depends on the reliability of the inverter.

We went back to just installing the bug-eye units. They also fail, but at least they fail one at a time. The biggest issue with having a lot of bug-eye units is battery maintenance and replacement.
 
On a side note, does anyone have a good calculation for power savings when dimming a driver? The drivers I have are non-dimmable, but for the emergency lights I could replace them with dimmable drivers and reduce the number of lighting inverters needed. The lights during normal operation are 50W each but I'm sure if I model at 10W or 20W they will still pass egress requirements.

D. Castor said:
I've been down the lighting inverter route - it's always been a problem. The inverter is going to be the LEAST reliable thing in the system, so if you really have to have lighting, you'd need two inverters. With an inverter, everything depends on the reliability of the inverter.

We went back to just installing the bug-eye units. They also fail, but at least they fail one at a time. The biggest issue with having a lot of bug-eye units is battery maintenance and replacement.
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Hmm. How bad are we talking for the failures? The units I'm looking at are 3 year warranty with an additional 7 years of pro-rata. Most of the rooms have more than one led panel that needs emergency backup and it looks like I'll need at least 3 inverters, so if we run the led panels from different inverters in each room that should ensure that if there is a power failure and inverter failure between tests then at least people are unlikely to be in pitch black.

The problems I have right now with switching to bugeyes is that it's in a cleanroom environment so they are harder to deal with than the surface mount lighting panels, having to redo photometric(only maybe a couple hours of work but I'm crunched for time and the overhead lighting backup is already on my approved permit set), procure them, and then electrical contractor is gonna hit me with a change order if he suddenly has to wire 50 more fixtures. Plus I'm kinda tight on capacity and breaker space on my existing panels, so I was planning to run the inverters from a distribution panel that has the capacity. Each of my lighting breakers is supplying just about the max number of lights, so I'm not sure if I can squeeze in the bugeyes without splitting into more lighting circuits. On the positive, up-front cost of bugeyes is about 50% of the cost of the lighting inverters.
 
Knightryder12 said:
Your lighting rep (if you are using one) should have lighting inverters as one of his companies that he or she reps, ask them. They will also be able to help you size it properly.
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No lighting rep... everything came direct from China(against my professional opinion) getting field certification hasn't been as bad as I expected thankfully. So glad I'm not on county land it would be a very different story.
 
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