I just went thru this process this summer when we replaced all the wiring and devices on the mast as part of the re-rigging process.
I tied nylon light line to each cable as I pulled it out of the spar. There is an internal pvc tube but it is real hard to fish a wire into it inside the top of the spar without pulling the masthead casting off, which I did not want to do.
I went with the conservative method and kept the circuits separate. I have a new vhf coax to the masthead plus a 12 volt cable for the new masthead LED anchor light. The other 12 volt cable goes to the combo steaming/foredeck light on the face of the spar about halfway up. Then, just to make it interesting, we pulled a new cable for the windinstrument at the masthead. (FWIW we have no tricolor or strobe.)
The original wire that Ericson put in for the 12 volt stuff was undersized. Everything is now 14 guage.
I should have put 18 guage in for the LED anchor light, but I was in a conservative mood at the moment...
FWIW it was amazing, after inspecting all the old fixtures installed in '88, that some of 'em still worked at all. Just taking them apart broke some of them.
:eek:
The old anchor light was a ruined corroded mess; the old vhf antenna came apart upon removal, etc. etc.
I asked the yard folks and a surveyor and both were against the "common ground" idea. Since all of these folks have thousands of sea miles behind 'em I guess they are entitled to like the "belt and ssupenders" approach to things.
Good luck on your project.
Loren in Portland, OR
Olson 34 #8