Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I'm getting ready to move some equipment to a data center and they are asking for a maximum power draw that my equipment would have so that they can install the appropriate circuit breakers for my server rack. Though they gave me a general equation to use to estimate the maximum watts for each unit, my math just doesn't seem to match what Dell has on some of their tech specs pages.

The equation they gave me was "volts X amps = watts". That in mind I calculated that a Dell PowerConnect 5448 should have a maximum wattage of 375 watts at 208 volts and 1.8 amps.

This though doesn't match what Dell states about the power supply on their tech specs page for the unit. The maximum should be "75 watts"? Can someone tell me what the correct maximum is and how to math it out myself?

http://www.dell.com/us/highered/p/powerconnect-5448/pd

share|improve this question
    
One issue you may run into is that 'power is not voltage times amperage'. It is 'voltage times amperage times PowerCorrectionFactor`. Just how that last factor works is not clear enough for me to explain, though wikipedia does attempt it. – Hennes Sep 9 '13 at 13:37

This tool on APC's web site will do the calculations for you, and already has the specific parameters for all major brands of equipment pre-loaded (Dell included).

http://www.apc.com/tools/ups_selector/index.cfm

Go there, click "Configure by Devices", then "Networking", and select Dell from the drop down list at the top and click submit. Then pick the model of equipment you're using and go from there. You can put in multiple units with different specs (like single or dual power supplies - which makes a big difference).

Click "Add to Configuration" and it will tell you all the power totals for each piece, and in total.

share|improve this answer
    
+1 Very handy tool – Dave M Oct 12 '11 at 21:10
    
Thank you, that tool was very helpful. – CokaKola99 Oct 13 '11 at 16:33

I'm not sure how accurate my UPS is, but according to my UPS, the power draw of my 5448 at idle is 35W. This is with no devices connected to any of the ethernet ports and no activity.

I am not sure what the load power draw would be, as I don't have enough devices to really load it down. However, the switch itself says 1.8A @ 100V, so it will never draw more than 180W.

share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.