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## Poe Power switches

Dears,

I was configuring a 9300 switch with 48 port and full poe and need to know i shld keep the redundant power supply,

as a math say that we need to have a redundant power supply with one power supply it will not work i need a confirmation for the same from you experts

48 X 30W = 1464 and the power supply available in the switch is 1100 , y that so  ???? any clarification Please ??  hence everybody will say me that not every phone is occupying 30.5 W most of them are occupying class 2 or class 3 ,

if incase i need to do sizing then which aspects has to be considered.

how much power resources i shld keep for system to run leaving power for POE+ ports

Thanks

9 REPLIES 9
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## Re: Poe Power switches

what device you referring here 30 consumption ? maximum of POE phone is 15.4W

15.4 X 48 ports = this what you need.

If this switch critical suggest to have redundant PSU.

here is calculation tool for PoE for 9300 and others.

https://cpc.cloudapps.cisco.com/cpc/LU.cpc

BB
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Hall of Fame Guru

## Re: Poe Power switches

I was configuring a 9300 switch with 48 port and full poe and need to know i shld keep the redundant power supply,

as a math say that we need to have a redundant power supply with one power supply it will not work i need a confirmation for the same from you experts

Redundant power supply is for redundancy, i. e.  if the primary fails, the backup takes over.

Contributor

## Re: Poe Power switches

thanks for you both

lets do the math if incase my switch is connected with phones class 4 POE i.e 15.4 so the math will be 15.4 * 48 = 739.2 and the power supply supplied on CCW for configuring the switch is 715 W so how things are working. ????

and also leo confirmed that the redundant power supply is for redundant not for sharing the power among each other so according to the math (15.4 * 48 = 739.2)  we have only 715 W

Please elaborate ??  there is sense behind this cisco has not designed on the fly  but i m not able to understand.

thanks

## Re: Poe Power switches

15.4 is maximum consumption of the device for the PoE phones, we do not see what is the device connected in your environment, some may have less power consumption devices, we do not at the stage until we get output as below requested.

Login to switch and show power inline will show the each device consumption.

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Contributor

## Re: Poe Power switches

Dear Balaji,

so the math shown in the previous email is according to the 15.4 lets assume 15.4 power consumption for 8845 phones which are 48 no's connected to the 9300 switch and so the math will be 48 * 15.4 = 739.2 and if i m installing only one power supply 715 W then how it will be sufficient ???

Please find the attached screenshot of the power supply provided for 9300 switches

## Re: Poe Power switches

I have attached based on your information for 9300-48P-E with 8845 all ports connect to these phones and you need as per the requirement.

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Contributor

## Re: Poe Power switches

Dear balaji,

the report generated by you was by 8945 phone with 6.4 W power consumption, however i didn't understood the calculation of the table mentioned Power supply Details, can you elaborate more on this table math.

i have generated a report in which i have chosen  device with 15.4 W consumption, please have a look on the report and suggest what do you understand, hence i can see the warning on the page.

thanks

## Re: Poe Power switches

May be my typo when i was intent to type 8845, it went to other model i guess.

For your devices you need - 48 x 15.4 = 739.20 So you need PSU need of 1100WAC this is recommended ( since it got available PoE 830W)

If this critical, i go 1100 X 2 PSU for High availability.

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Enthusiast

## Re: Poe Power switches

Is the 1100PSU even available as primary for the 9300-48P model ? according to CCW , it is not.

Strange, because as secundary , you can choose the 1100W model, but not as primary (??)

Also, the specs list that the POE budget of 9300-48P model is only 437W as "available poe budget" when using the 715PSU. does it mean you can only connect 29x 15W phones ? or 14x 30W APs ?

if we install the 1100W anyway as primary, will it boot (supported) ? will it increase the "available poe budget" to abvove 437W ?

Does installing a secundary power supply increase the PoE budget from 437 to 874W, allowing 28x 30W APs (but non-redundant then) ?

this is not at all clear and asks for some clarification from cisco.