Rewiring old farmhouse and upgrading residential service from 100 amps to 200 amps. Utility company has requested new service be located at opposite end of house. I am locating new service panel at this "new service location". My question - I am going to be feeding new 200 amp panel off of 100 amp panel until utility company makes switch over (25' from each other). New service panel has neutrals and grounds bonded. Is it permissible to run 3 conductor SEU to power up this panel seeing how it is NOT a sub-panel? I stress that this is only for purposes of "firing up the panel" until utility switches over service. I have done numerous jobs like this in the past and am just now questioning it. Looking for other's thoughts.