nanog mailing list archives
Re: Why choose 120 volts?
From: Owen DeLong <owen () delong com>
Date: Tue, 26 May 2009 14:06:57 -0700
On May 26, 2009, at 1:48 PM, Alex H. Ryu wrote:
Also, adding followings. 5) availability from local power provider(s)
I don't know of anywhere in the US/Canada where power comes into thebuilding as strictly 110-120V. That is almost always delivered either as
1 leg of a 3-phase 208 service (most commercial/industrial deliveries) or as two hots (240V across the two hots) and a neutral (120V from either hot to neutral). Most datacenters are taking much higher voltage feeds from their utilities and most of the readily available step-down transformers and UPSs will produce 208 three-phase or 240V as described above. I am not an expert on power outside of the US, but, to the best of my knowledge, Japan's 100V/50Hz is one of the few other countries using less than 208V as their standard.
6) local regulation such as fire department safety rules...
I seriously question this one. Can you point to any examples?
7) for your own safety... (120V may not kill people, but 240V can do...)It's relatively easy to kill someone with 12V, so, I don't see how 10x that is significantly less dangerous than 20x. Sticking your fingers in a light socket is going to hurt regardless of the voltage. Yes, 240V can hurt more and faster, but, at the end of the day, it's not significantly more likely to kill you than 110. Fortunately, most servers don't have light sockets
in the high voltage portion of the server.
If you want better, why not just have everything to DC power ? Something like 48V...
There's a whole host of reasons, but, the biggest one boils down to cost... Cost of the larger wires, cost of the increased line losses, etc. Owen
Alex Wayne E. Bouchard wrote:1) Equipment used to not be dual voltage 2) For smaller scale, 120V UPS and distribution equipment is usually cheaper 3) 120V embedded itself into operations as a result. 4) We're all lazy and hate change. On Tue, May 26, 2009 at 12:39:10PM -0700, Seth Mattinen wrote:I have a pure curiosity question for the NANOG crowd here. If you runyour facility/datacenter/cage/rack on 120 volts, why?I've been running my facility at 208 for years because I can get away with lower amperage circuits. I'm curious about the reasons for usinghigh-amp 120 volt circuits to drive racks of equipment instead of low-amp 208 or 240 volt circuits. ~Seth--- Wayne Bouchard web () typo org Network Dude http://www.typo.org/~web/
Current thread:
- Re: Why choose 120 volts?, (continued)
- Re: Why choose 120 volts? Ray Sanders (May 26)
- Re: Why choose 120 volts? Alex H. Ryu (May 26)
- Re: Why choose 120 volts? Barney Wolff (May 26)
- Re: Why choose 120 volts? Steve Bertrand (May 26)
- RE: Why choose 120 volts? Dave Larter (May 26)
- Re: Why choose 120 volts? Joe Greco (May 26)
- Re: Why choose 120 volts? Jared Mauch (May 26)
- RE: Why choose 120 volts? Dave Larter (May 26)
- Re: Why choose 120 volts? Alex H. Ryu (May 26)
- Re: Why choose 120 volts? Owen DeLong (May 26)
- Re: Why choose 120 volts? Brian Raaen (May 27)
- Re: Why choose 120 volts? Dorn Hetzel (May 27)
- Re: Why choose 120 volts? Peter Dambier (May 27)
- Re: Why choose 120 volts? Michael Thomas (May 27)
- Re: Why choose 120 volts? Peter Beckman (May 27)
- Re: Why choose 120 volts? Iljitsch van Beijnum (May 27)
- Re: Why choose 120 volts? Seth Mattinen (May 26)
- Re: Why choose 120 volts? Chuck Anderson (May 26)
- Re: Why choose 120 volts? Chris Adams (May 26)