He is a Senator, and has been for about 30 years. When he was elected, he, like everyone else serving in the Federal Government, moved to DC. He may keep a North Carolina residence, and live here when the Senate is not in session, but he spends MOST of his time in DC.
Also, Libby Dole's husband was a Senator for much of the time since she last served in a Federal job. If your husband is a Senator, would YOU live 350 miles away from him, just so you could keep a North Carolina address??
She didn't stay in DC when Bob went home to Kansas -- she lived in KANSAS with him. I still want to know why, if she was so hot and bothered to be a member of the US Senate, she didn't run for the seat from Kansas, not NC. (Unless it was going to be easier for her in NC, as with Bill's Wife-In-Name-Only and NY).
Now that I understand your comment on Helms, I'll grant you that point. Why I have been a big supporter of the "Cut their pay and send them home" movement. It's disgraceful when elected members of either chamber complain that it's "too inconvenient" for them to go back to the hometown more often than just the month-long breaks and campaign season.