I am trying to design a tap ahead of a main breaker for a Hangar door, and NFPA 409 requires a tap ahead of the main. Can an indoor transformer, dry type, 13.2kV pri, 480V secondary be tapped inside the transformer cabinet with 600V insulation wire. Would the tap conductor be required to be rated 15 kV, the transformer is not compartmentalized and is unisulated bus bar on the 480 side to the switchboard. The transformer is up against the main breaker section, all customer owned and metering is not an issue. Any code references would be appreciated.

NFPA 409:"5.7.2 The power source for hangar doors shall operate on independent circuits and shall not be deenergized when the main disconnect switches for general hangar power are shut off."
Seems to me you could set it up so that you won't have to connect ahead of the main. Why not have a main distribution panel fed by the transformer, one feeder would be to the general hanger panel, a second would go to the hanger doors panel.

Earl