I will install 3 stripes of w21812b with 300 leds each. The wled show I will need 50A.
When I put more than 8A on the power wled warns me that i wil need use resistors. My question is, what ones ? How do I calculate that ?
I think you may be confused. When you set the brightness limiter to higher values it says:
“Your power supply provides high current.
To improve the safety of your setup,
please use thick cables,
multiple power injection points and a fuse!”
Nothing about resistors.
It is just warning you that if you don’t use correct wiring rated for the high current you are at risk of starting a fire.
Fuses can help to minimize the chance of drawing too much current due to many factors, the main one being a short circuit.