If your workflow requires the capture of the duration of non-billable breaks such as lunch etc, you can enable a break button in the kiosk that is mapped to non-billable task.

In the Kiosk tab of the settings (Administration -> Settings), select the non-billable task you would like to use to track your breaks in the Default Break Project and Default Break Task dropdowns.  Click Save All to apply the kiosk settings.

When the default break project and task fields are populated, the kiosk will then display a Start Break button in the Enter Time and Materials tab.  Note: If the start break button is not available, the default break project and task settings haven't been saved correctly.

Clicking the Start Break button will immediately start a timesheet timer for the specified break task.  This will then need to be stopped and saved when returning from the break and starting billable work again.   If you are working on the same task as before the break, Resume Most Recent will quickly start the previous timesheet task again.