See this link,
http://www.admin.ch/ch/f/rs/8/822.11.fr.pdf , assuming the type of business you are inquiring about is covered under this for workers in commerce, industry, and craft industry. There are some exceptions also, see the first page.
In particular art. 15, which covers breaks-- says a break of 15 min. if work day is at least 5 hours 30 min., break of 30 min. if work day is at least 7 hours, and 1 hr. if the work day is more than 9 hours.
Also for completeness, the swiss code of obligations, Title 10, covers work contract/employment conditions. Scroll down here to Title 10,
http://www.admin.ch/ch/f/rs/220/index2.html