mkx is correct and is confirmed in this thread. The cAP AC can be powered from the passive PoE on the RB4011’s ether10 port. Thank you, mkx.
Ok thanks. Is there any danger in damaging the cap ac if I try it through the RB4011 port?
I guess that if dammage would be done, it would be on RB4011 … all PoE out devices by MT have some current limits and one can only guess what would happen if that limit is exceeded. The PoE injectors, OTOH can inject higher currents.
I guess the only thing that might hit cAP ac is continous reboots if supplued current wouldn’t be enough.
Hmmm. Frying the RB4011 sounds more dangerous than the CAP AC getting damaged.
Maybe I’ll just try the injector first.
Check the product pages of both devices … specially the Powering section. My assessment says that powering cAP ac from RB4011 PoE out port is safe. But then, the gear is yours, do with it whatever you think it’s safe … after all, if it breaks, you’ll keep the pieces 
Started configuring the new gear today. I’ll start a new post, and link it here.
Seems prudent, considering its all new gear. RB4011 (wired), plus a CAP AC.
New post - different equipment
http://forum.mikrotik.com/t/rb4011igs-rm-plus-cap-ac-vlans-in-the-home/135755/1