Devon and Cornwall Police staff rejected new pay proposals.
The force revealed the outcome of its highly sensitive job evaluation scheme earlier this month.
Overall, 363 members of staff, 16% of the civilian workforce, were due to see their basic pay cut following the assessment of skills and salaries. And in a handful of cases staff stood to lose more than £10,000 a year.
Conversely, 28% of about 2,300 workers would have seen their pay increase, while for the rest it was due to stay the same.
But a union ballot on the proposals saw 51% vote against and 47% in favour, with 2% of papers spoiled, on a turnout of almost 70%.
Stuart Roden, from Unison, said: “Clearly those people losing money were unhappy and even some of those whose pay was rising didn’t like the system and thought it was unfair.
“We were convinced that we had done every check we could and our reps had crawled all over it. But I think there is still some history from 2005 and we started from a position of mistrust.”
Mr Roden said they would be “reflecting over the next few days” before starting talks with the force on a new way forward.
Chief Constable Shaun Sawyer said he was “disappointed” with the result of the vote and would need “some time to consult with the trade unions” to understand the reasons behind the rejection.
“I have always made clear retaining our current grading and pay system is simply not an option,” he said. “I will therefore need to consider how we will move forwards from here and ensure that we have a fair and equitable grading and pay system that is fit for purpose for the force and the public we serve.”
It has taken the force nine years to remedy the failed scheme in 2005 which resulted in hundreds of civilian staff walking out in disgust. Then some 800 staff were told their salaries were being cut.