Service mast

[Kessler4130]

This may be a stupid question, but after looking I cannot seem to find anything prohibiting parallel cables in a service mast. I have looked through the local providers manual and they have an installation designed for a single phase and three phase service in the same mast, but neither the power company or the NEC seem to prohibit it (unless ofcourse I missed it entirely). My concern was the 4 or more current carrying conductors in the 3 or 3 1/2 inch mast, but is the mast considered a raceway or simply a support, so would derating even be an issue. For the sake of arguement lets assume 2- 2/0 SE cables to keep the size down, and a 3 1/2 inch mast for a 400 amp residential service, can this be done inside the NEC's requirements ? Or is a second mast required.

Any information would be appreciated

 

[sc57ford]

Take another look at Art.310.15(B)(2) Exc. 3 (2002 NEC). Derating factors shall not apply to nipples less than 24 in. I believe a mast would more than 24 in. therefore, derating is a must.