I have a customer that is going to put about 30 servers in his garage (home office). If the power goes out he wants to ensure the servers continue to run.
There are 8 computer bundles. Each one requires a 20 Amp circuit.
My first instinct is to suggest UPS battery backups for each of the bundles. Then install an automatic transfer switch and generator.

My question is: is there a better solution for this than what I have proposed.

Many thanks,
Byron

How much reliability is he willing to pay for? Does he need to be up 6 nines? (99.9999% of the time)

How about maintenance accessability?

How about heating and or cooling requirements?

Did he also include the network, communications, and remote data sources?

How is he going to load test the generator?

Are the 20 Amp bundles 120 or 240 Volts?

My first suggestion is to go with dual power sources for each machine. Feed one side from the House panel and feed the other side from a LARGE centralized UPS with a suitably sized transfer switch and generator. Feed the Normal source of the transfer switch with a separate dedicated feed from the house panel.

Well there's a blast out of the past.

8 circuits at 20 amps each? Sounds like a serious operation. If he's sending out spam, break stuff for us, will you?

I see a significant load there. Add in the lighting and HVAC requirements, and my first thought is: this is too big for a home operation.

Let's start at the very beginning.

For tax reasons alone, this room should have it's own meter. I doesn't have to be a PoCo account; he can tenant meter it.

The next stop is a transfer switch; looks like you'll want a 200 amp one.Then he's ready if he ever wants that 50Kw generator. At least put the can in; you can probably buy the guts later.

Then there's a 1:1 transformer, 48Kw, to isolate the power; helps reduce transients.

Next is a BIG pull can / splice box .... if you want the HVAC on the UPS. If not, skip the can, and put in a panel.

The panel is next. I'd consider adding a surge suppressor at this point. That's another $2K expense.This may not be necessary, as the UPS's may have surge protection built into them.

When you get to each rack, I'd incorporate a separate UPS into each rack. Your circuit supplies the UPS, and the UPS then powers the servers. When not supplying back-up power, the UPS serves to protect everything from transients.

Home Office & in his garage? Boy...zoning would love to see this if it was here.

Reno is on the track, but this would be a 'tough sell' permit wise here.

I'd run these computers on 240V ... through a single phase 208/240V UPS ... unless they are spam engines, in which case I'd give them a dose of 13800V.

I agree, do check to see if it is spam servers, and maybe let a few power cords/Ethernet cords go missing, or even pop open a network switch or 2 and hit them with a 1 1/2 paddle bit to the circuit board

What kind of "servers" are we talking about? If these are PCs we are vastly over rating the load.
What does the "clamp" say?

I have had a Kilowatt on this 24/7 cludge here (P4 2.8GZ, 2 hard drives, router, DSL modem, LAN switch, External DVD, monitor and an ink printer, electric train, amp/speaker on a UPS)
It shows 201 KWH for 1112 hours of running. That is 180w average draw.
He could quite easily run 8 machines on one 20a circuit but I could also understand why you would want to split this out across 8 separate UPS's.

If these servers are really PCs he is probably going to save money on his hardware using 120v since that is what they sell cheap and I doubt he would get 3p in a residence no matter what.
That is about a ton and a half of A/C the way I read it.

John, the way zoning works here is you can have a business in a home as long as you don't have customers stopping by ... very often.
My consulting company "Blue Light" is licensed out of my home.

I see this is California. In Northern California he might get away without a whole lot of A/C if he just ventilates the garage. The energy police might like that better. PCs are really a lot tougher than the "computers" of old. They don't need that "glass house" environment. I have had one in my car for almost a decade, cranking up at 120f or so whenever I get in the car in the summer. There is also one that has lived in my garage for almost as long, including surviving a fire.

Your kidding? In the Sacramento Valley in the summer temps can run in the triple digits for days, the one advanage of the Sacramento area is that the Delta breezes cool things down at night.Death Valley it's not, but it's quite hot in the summer here.

It is never recommended to HVAC on a UPS. Some room ventilation fans maybe but not HVAC. The servers will survive the time it takes for a generator fire.

The only way to maintian service in a power interuption is a UPS. For extended outages you add a generator.

Sorry Norcal, For some reason I thought it was cool there.
My mistake.

But Norcal, it's a DRY heat.

Jdevlin, that is a very good point about the HVAC. Thank you.

This is one of those times where we really are not getting the complete story - as suggested in the elaborate plan I had suggested. Next thing you know, the OP will be back asking about COPS wiring methods.

My point was, before we get too far we really need the actual load. Then you size the HVAC to the sensible heat from the hardware, plus the latent heat and the room load.
I agree you don't need the HVAC on the UPS if he is going to have generator backup.
Are these 30 servers redundant access to the same system or do they all need to up? That can make a difference too.
In real life, if he wants his availability to be anything in the "nines" he should have an alternate site. There is just too much that can happen in a system with a single point of failure like that. (Earthquake, flood, fire, criminal mischief etc). The biggest single point of failure is probably his broadband carrier anyway.

Just a follow up. The customer took one look at the price of a gas fed 10kw generator and automatic transfer switch and has opted for a manual transfer switch and to purchase a tandem Honda generator set up.

The Servers are basically old PCs. I have put it on him to figure out if the UPS system will suffice. I've been told that even with those installed there will be a flash in the power supply. I'm not sure if that causes a problem for his PCs or not.

It seems he is on a rather tight budget, who isn't these days.

Thanks for all your thoughts!

I have regular old APC UPS's on my PCs and they work fine. The PCs handle the switching glitch OK. If he keeps fresh batteries in the UPS (replace about every 3 years) he will be able to count on about 80% of the rated capacity. That should give a reasonable reliability if the system is attended but it sounds like a one man band operation so a power cut at 3 AM may bring him down if he doesn't wake up, start the genny and flip the transfer switch.

I was going to chime in about the benefits of using a central UPS over small rack-mount units, but if he's just going with an MTS, he's probably not going to be able to do it "right".

Unless these are massive industrial blade server chassis, he doesn't need a 20A circuit for each server. It depends on the type of server, but if they're just PCs being used as servers, they probably draw around 1-2A each. My advise is to put a clamp on there and measure the current, and then buy a SINGLE UPS to power it all. Use the UPS to supply a panel, and feed all the servers from there. KVM and monitors and all do not necessarily need to be on the UPS, but it it's helpful if you have to shut them down when your gen doesn't start. HVAC should NOT be on the UPS, nor should any printers. E-lighting: yes. Normal lighting: no.

If he's on a dime, there are vendors that sell used UPS systems and would be pretty reasonable for a larger system. (I bought a used parallel-redundant 50kVA Powerware system last year as a training UPS for a ton cheaper than buying a new one- if you don't need five or six 9s, you can get away with it.) He's probably only looking at a non-redundant unit somewhere in the 3-5kVA range for 30 PC-based servers. If he can't afford a 10kW generator or an ATS, he's probably not going to be able to afford an UPS, either. He might want to scale down his plans a bit.

On the other hand... 350VA APC Back UPS can be had for about $30 on sale. And a 3kW gen at Lowes for $400.