My 2 cents on this topic: If you can do this small scale (and this may not apply to your situation) get a "Kill-A-Watt" and hook up each of your devices through it. It will tell you EXACTLY how may watts/amps/etc each device is actually pulling from the wall. You can test different devices under different conditions (like the power used at startup or when running at full load.)
The Kill-A-Watt (and other devices like it) are pretty cheap (under $50) and tell you exactly what you're using. As I mentioned, this is good for a small scale project. If you've got hundreds or thousands or different devices, then this probably won't work for you. Chris On Fri, May 8, 2009 at 10:18 PM, Jack Coats <j...@coats.org> wrote: > When doing your power spreadsheet, go get a clamp on amp meter, and measure > some 'typical' devices. Nameplate numbers are much higher than most > configurations. > > Or better, have an electrician come through and measure your REAL power > requirements. > But take into consideration, if your systems are turned off, turning them > on hits you > with an extra high surge load for a few seconds for each system. This is > due to startup > current for motors in fans for cooling in equipment, disk drives, etc. > This surge can be > significantly higher than 'running' power, and can shift the power load so > it is not insignificant. > > Some disk drive have 'staggered' power up options. I you have lots of > drives, consider > re-strapping the drives for staggered startup. In an old SCSI data center > systems that > some folks were building, they built several LARGE SCSI disk farms. After > hearing about > that I mentined it to them over a cup of coffee. They just looked at each > other and excused > themselves to start opening up all the large SCSI raid enclosures so they > could re-strap all > the drives. Even a large commercial data center (that was designed for the > old big IBM > mainframes) would stagger under a thousand or more of SCSI drives coming up > at the same > time after a power outage! > > It is a challenge to know how to size everything. Oversizing is a costly > option to not doing a full analysis. > > IHS ... Jack > > > > > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "NLUG" group. To post to this group, send email to nlug-talk@googlegroups.com To unsubscribe from this group, send email to nlug-talk+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/nlug-talk?hl=en -~----------~----~----~----~------~----~------~--~---
