Power Sizing/Calculation for Switch WS-2960XR-24PS-I

[MUNISHGOPAL1]

Hi..Want to know how to size the Power for the Switch.

As per Datasheet ws-2960xr-24ps-i Switch will consume 370w. but in case my actual load is less(say i want to use 18 PoE Ports at 12.9w. How to size the UPS?

Shall i size as per the Datasheet for 370w or i can size the UPS for 18x12.9= 230w.

Please help me in exact power sizing.

Thanks in advance!! 

[Richard Bradfield]

the 370w is the power available for Poe, not its power rating.

If you are sizing for for an UPS, then the power rating of the switch is 0.49Kva 

always allow for maximum

HTH

Richard.

[MUNISHGOPAL1]

Dear Chrbradf1,

First of all thank you very much for the response.

Yes i agree & understand with the same as well

But here i know my rest of the ports will be free. customer is not going to use those free ports in any case. and here i want to save sove cost on the power sizing.

Please guide me how much power atleast i need to plan as per current load

Munish

[Richard Bradfield]

well basic maths tells me if the switch is rated at 0.49Kva that is 490w so the difference between that and total POE power is 120w, so my guess is if you are 230w for Poe, then the total power requirement would be 350w, but I think it is dangerous to take it to that level what happens if you have more POE devices in the future, sizing the UPS to that degree could mean you would have problems.

[MUNISHGOPAL1]

Dear chrbradf1,

Yes True & fully agreed with you.

But here Scenario is bit different. The actual requirement is i would be connecting connecting CCTV camera's to this Switch & each Camera PoE power requirement is 6w(max.) if i take that calculations the 24x6=144w, plus 120w = 264w. but here Datasheet says 370w keeping full load with each port working on full capacity. But my requirement is less here

As all ports are full further(in future) their will not be any problem

The question is can we go with UPS sizing for 264w. As we are having more than 50 switches on different location & we are sizng UPS power. If the above calculation is correct we can save a lot in UPS & Cabling to a large extend.  

Waiting for a valuable response..Appreciate!!

Regards

[Richard Bradfield]

if you are never going to go above 6w on any port then your calculations are ok. though I would still allow a little bit extra, make it about 300w (.0.3Kva)for the switch. you never know in the future you might have some 15w cameras!