They (manufacturers like b-line ect) make a 'mast kit' if over a roof. It consists of some 1/2" or 3/4" RMC fittings and rings that go on the conduit, and some brackets to bolt to the roof. You get to thread your own RMC for it. But this is identified in the instuctions for the purpose.
230.28 Service Masts as Supports.
Where a service mast is used for the support of service-drop conductors, it shall be of adequate strength or be supported by braces or guys to withstand safely the strain imposed by the service drop. Where raceway-type service masts are used, all raceway fittings shall be identified for use with service masts. Only power service-drop conductors shall be permitted to be attached to a service mast.
