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Dual power supply and POE effect

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  • 1.  Dual power supply and POE effect

    Posted Mar 17, 2022 05:45 AM


    Good day

    I need to ask about if the switch POE Capability and maximum power increase when connecting dual power supply for switch or not? 

    i mean is there any effect for connecting dual power supply on the switch Max POE ?

    Ahmed Elshindidy

  • 2.  RE: Dual power supply and POE effect

    Posted May 18, 2022 11:57 AM

    Generally, yes. Dual power supplies increase your maximum PoE capacity. But a lot depends on your model of switch and model of power supply. PoE switches tend to have an upper limit of what they can support. And power supplies come in a variety of wattages.

    Generally speaking, you should gain PoE capacity on any 48-port PoE switch. 

    Dual power supplies also provide your switch with an important level of redundancy. 

    See this example of an Aruba datasheet:
    Page 5, quote: "Optional secondary power supplies to increase the total available PoE power"

    As you can see from the datasheet, different switches have different maximums. Your power supply needs are affected by the number of switch ports, type of switch (Class 4 PoE vs Class 5 PoE), and the type of devices you will be using (basic VoIP phone or high-end access point). 

    Using that datasheet as an example, say you purchase a 48-port 6300M JL661A. You install a single midrange 1050W (JL087A) power supply.  The base switch needs at least 200W to power itself, leaving you with a PoE budget of around 800W. When you add a second 1050W JL087A, again a portion of that power supply will be reserved for redundancy to power the base switch. The rest will be added to your available PoE budget. 

    The maximum PoE for the JL661A is 1440W (30W per port), so a single 1050 won't get you all the way there. Two 1050W power supplies provide the maximum PoE potential and redundancy. Just keep in mind that you will lose PoE capacity if a power supply fails and devices might lose power. If that's an issue, consider the 1600W JL670A which independently provides around 1400W of PoE per power supply to that switch.  

    For the JL659A model, the max PoE is 2880W (60W per port). So for this model, you probably want to start with the JL670A power supply and use two for redundancy and the ability to achieve full 60W capacity to each port. 

    To recap, when you're deciding on a second power supply, understand what your switch is capable of and have a good idea of what kind of devices you intend to power. 

    Greg Meinert