New copper main line

I replaced the 1" water line from the street to the house with copper. The remainder of the house plumbing is Galvanized pipe over fifty years old. My question is should I isolate the connection between the pipes. The plumber just connected the two pipes as it enters the house with a copper 90 elbo, no valve or nylon bushing.
Thanks,

First I would get a new plumber. I am surprised that the code inspector did not notice this. You will get galvanic corrosion for the mismatched metals (a simplification) resulting in an eventual leak or break. You are correct that a non metallic connector should have been used.

Gene is correct about what should have been done, Jeff. Correct practice is certainly to include a dielectric union or other electrical isolation. But the statement that you will get an eventual leak may be a little strong. I served as a plumber's helper way back in high school and college and can't count the number of direct copper to steel connections I saw.

Further, there may be telephone line grounds, or other grounding straps attached to the galvanized pipe which the plumber did not wish to put at risk.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey