(1) PoE Port can supply upto 15W of power to device, while PoE+ can supply 25W approximately. Other classes like 802.3bt, etc can supply even more.
(2) A PoE camera typically uses 6-9W of power during day (based on the resolution) and additionally another 2-3W of power during night due to IR LEDs firing up in low light
Therefore most general cameras can be supported using a standard 802.3af switch only and 802.3at is not required. same applies to entry level Wifi Access Points too. Be careful and note down the total power supplied by switch (capacity) and make sure the connected cameras draw do not exceed this otherwise, few cameras may randomly shut off and on.
However specialized camera like LPR, ANPR, PTZ, etc which are bigger and more CPU intensive require more power. They need 802.3at or better and therefore would need a PoE+ switch. However this is not optimal as the quantity of such cameras is usually less than than the general PoE camera. The best balance therefore is a camera with 15-30% PoE+ ports and 70-85% PoE Ports, rather than a switch with 100% PoE+ ports.
In our apartment setup, we have not used specialized camera till date and the maximum power drawn we have seen with almost all ports full is around 120W out of the 193W maximum that our switch can supply. So we think that in future of we introduce a few such special camera, then we should be able to accommodate them because our switches support upto 4 PoE+ ports
- Suman Kumar Luthra @ APRC-P3 Telecom Sub-Committee
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