Hartford - An effort to unionize 429 workers at the Millstone Power Station in Waterford failed Wednesday, when a count of votes cast in June tallied 183 in favor of joining the International Brotherhood of Electrical Workers Local 457, and 222 against.

The vote count had been delayed until the National Labor Relations Board ruled on which workers were eligible to vote. Michael C. Cass, officer in charge of the Hartford office of the NLRB, said 429 workers in the nuclear operations, outage and planning, nuclear site services and training departments were deemed eligible. The union had argued that 350 plant workers should be eligible to join the union, while the company had originally said it believed about 800 of the 1,080 workers at the nuclear power plant should be eligible to vote.

Cass said 10 ballots were challenged during the count, but since that would not be enough to affect the outcome, the results will stand.

Millstone spokesman Ken Holt said the company is pleased with the results.

“We’re pleased that employees had an opportunity to express their opinion and pleased with the professionalism displayed by everyone in this long process,” he said.

The first union-organizing effort at Millstone to come to a vote, in 2002, also failed. An organizing effort in 2007 did not culminate in a vote.

John Fernandes, business manager for IBEW 457, said the 39-vote spread was “extremely close” and that the union would do some analysis to determine whether to launch a new organizing effort in the near future.

“The company spent a tremendous amount of money to get the results to go their way,” he said. He said Millstone owner Dominion’s “high priced attorneys” successfully argued for a larger voting group than the union deemed appropriate, including some supervisors, he said.

Leading up to the vote, Dominion urged workers to vote against the union in a campaign that included DVDs sent to the homes of workers, Holt said in June. On the DVD, company managers talked about why they believed a union would not be beneficial for employees, according to Holt.

The company also hired consultants to meet with the workers to persuade them against the union.

IBEW’s organizing efforts began in the spring of 2013. Fernandes said it was prompted by worker dissatisfaction over benefit cuts and inequities in pay rates different workers receive for the same jobs.

IBEW also represents workers at Connecticut Light & Power.

j.benson@theday.com

Twitter: @BensonJudy