Are ceramic magnets (ferrites) considered "nonmetallic substances?"

While ceramic magnets are not metallic, and therefore not disallowed by rule 3.e., rule 1 disallows energy transfers from the fan to the blade assembly that proceed by means other than the wind. If the blade assembly is magnetic, the ES would not be able to know whether an interaction between the magnetic fields of the fan motor and blade assembly is transferring energy. Therefore, magnets may not be used in the blade assembly.