The present invention relates to a connector box adapted to be at least partly embedded in a fiber-reinforced part of a wind turbine, where said connector box comprises a flexible base part and a sealing part. The sealing part seals off and protects at least one compartment between the sealing part and the base part during manufacture of said fiber-reinforced part, but can be partly removed after manufacture making said compartment accessible. The base part is adapted to fasten the connector box in the fiber-reinforced part by having a larger circumference near its bottom than near its top. Further, the invention relates to such a connector box fixating a part of an element in the compartment of the box and making a second part of the element accessible from the compartment after manufacture.