She said that workers were expected to carry 30 cases at any one time.
But she said: "When I did the training I would have 15 cases and a long bedding in period as this was a new department."
Instead, she told the tribunal, just weeks into starting the job her department was told of the planned increase.
Things got so bad that she lost a series of files, she said.
She suffered a panic attack and went onto long-term sick in March, 2007.
Yaqub Rahman, for the Home Office, said Mrs Francis had decided at that point she would never return to that department under any capacity.
Mrs Francis agreed but Mr Rahman suggested she could have taken on an administrative role without the case load.
