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Joined: Sep 2003
Posts: 114
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,

Joined: Jul 2004
Posts: 787
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.

Joined: Jun 2004
Posts: 1,273
Well there's a blast out of the past.

Joined: Jan 2005
Posts: 5,445
Likes: 3
Cat Servant
8 circuits at 20 amps each? Sounds like a serious operation. If he's sending out spam, break stuff for us, will you? laugh

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.

Joined: Apr 2002
Posts: 7,383
Likes: 7
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.

Joined: Jan 2005
Posts: 354
pdh Offline
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.

Joined: Mar 2008
Posts: 144
Originally Posted by pdh
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 grin

“then we'll glue em' then screw em'”
-Tom Silva
Joined: Jul 2004
Posts: 9,935
Likes: 34
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.

Greg Fretwell
Joined: Jul 2004
Posts: 9,935
Likes: 34
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.

Greg Fretwell
Joined: Jul 2004
Posts: 9,935
Likes: 34
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.

Greg Fretwell
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