A:AnswerThere seems to be confusion here.
Nest operates on low voltage (around 24 volts). When you say baseboard, you have to specify if you're using hot water or electric. Hot water baseboards are run off a furnace which uses low voltage for tstat control. Electric baseboards are line voltage (120-240 volts). The only way you can use a low voltage tstat with that system is if you install a heating relay with a transformer. Definitely a job for a professional.