Does answering Barchu or saying Mizmor Shir constitute acceptance of Shabbat that prohibits further melacha?

ShabbatOnset of Shabbat

Synopsis

The Mechaber rules that after the community answers Barchu, even though it is still day, eiruv and insulating are prohibited because they have accepted Shabbat. For Ashkenazi communities, saying Mizmor Shir (or in later practice, Lecha Dodi) has the same effect.

Early Acharonim
Late Acharonim
Lenient
Strict
Lesser cited
Major authority

Discussion

Discussion coming soon.

The Daily Law

One question. Every opinion. Every morning.

A new halakhic question and the full spectrum of rabbinic thought, delivered daily.