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New Member

PoE max on 3560 switch?

I have a question regarding power utilization on PoE switches.

We have mostly WS-C3560-48PS and WS-C3560G-48PS PoE switches.  By looking at the 'show power inline' I see that the available power is 370.0 watts.  I also see on this command that our IP Phone models 7940, 7941 and 7942 are listed as using 6.3 watts and the 7945 is listed as using 12.0 watts.

My question is concerning the max.  If we do the math, we see that this switch switch can handle 48 of the 6.3-watt phones (48 * 6.3 = 302.4, max is 370 watts).  But if we were to have 48 of the 12.0 watt phones, math says we exceed capacity (48 * 12 = 576).

So will happen when we exceed capacity?

Also, are these REAL numbers?  I mean, I know enough about electricity to be dangerous.  I know that devices are usually rated at the max wattage they will use and that is usually during power-up when there is a surge while everything gets going, but that in actuality consumption drops after startup.  So, is this true for phones also?  If so, then can the advertised max wattage numbers safely exceed capacity?  What then is the actual running wattage consumption?

We're trying to plan for future growth & want to make sure we have adequate capacity.

Thank you.

3 REPLIES

Hey,You are right with your

Hey,

You are right with your assumptions regarding the wattage required by phones once they are operational but switch reserves the PoE as per the class of device and if you are installing all 7945 phones, surely you are exceeding the capacity and in this case PoE will not be provided to all the IP phones.

You may use the command 'show power inline police' to check the actual wattage consumption for a connected PoE device.

So my suggestion would be higher wattage PS unit.

HTH.

Regards,

RS.

New Member

Thanks RajeevshWhen you say

Thanks Rajeevsh

When you say "higher wattage PS unit", is that as simple as replacing the power supply in our 3560, or a whole new switch?

Thanks

 

Oops my bad, i wrote that

Oops my bad, i wrote that thinking you have newer 3750-X boxes. In case of 3560 it will be a new switch.

HTH.

Regards,

RS.

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