How do I find out if the PoE power source is sufficiently dimensioned?

You are here:

We recommend to use 48V adapter for PoE Injector (see anchor’s datasheet), to minimize voltage drop among the long cables. Since anchor consume just 2.5W roughly 50mA current rating is enough to power-up the anchor. For multiple anchors, just multiply 2.5W with number of anchors + allocate some power budget reserve.

If you would like to calculate voltage drop among the cable length, you can find some PoE calculators below:

Besides cable length, you would need to know some other cable parameters (AWG – American Wire Gauge, DCR – Direct Current Resistance, etc.) which directly affects the voltage drop.