Union leaders for Vectren Energy Delivery of Ohio utility workers picketed at utility locations around the Dayton area after a lockout by the company Friday morning.

The company said the labor dispute, which followed failed negotiations, is the first of its kind since the 1970s.

Vectren said the Utility Workers Union of America (UWUA) Local 175 rejected its last offer for a new contract for nearly 130 members. Vectren said it quickly put staff in place to “ensure safe a reliable natural gas service continues for its customers.”

The locked out workers include service and construction technicians, meter shop employees, office workers and regulator technicians who maintain larger distribution facilities like higher-pressure gas lines.

Kelly Cooper, president of Local 175, which is headquartered in Dayton, said the main hangup is safety.

He said the union wants specially trained personnel to respond to reports of gas leaks. Cooper said Vectren wants to change the response to the utility worker closest to the complaint as a way to reduce response times, adding that response times now are under 30 minutes.

“It takes years of experience to tell in a split second how to assure the safety of the customer,” he said. “The company locked out highly skilled employees and are now using people not as qualified. Vectren’s had some problems with explosions in the past. We don’t want that kind situation here in the Dayton area,” he said.

Vectren spokeswoman Chase Kelley said the utility uses a system of closest technician response in Indiana and wants to extend that to Ohio. In Ohio, she said, the nearest technician now responds during the day. Vectren wants this to be extended to the 24-hour period.

She said 60 replacement workers, including contractors as needed, are now on the job. They’re working 12-hour shifts instead of 8-hour shifts and are devoting themselves to time-sensitive work.

“The union’s argument has been they voted against the contract because of safety concerns and that we are proposing to send unqualified people to respond to gas emergencies. This is simply not true,” Kelley added. “The union alleges we would somehow be sending untrained workers when in fact, all our field employees have been trained to be first responders.”

Vectren Energy Delivery of Ohio President Colleen Ryan said the company has made a fair offer.

“We have worked in good faith with union leadership for many weeks — even meeting with a federal mediator — to package a very fair proposal,” Ryan said.

Staff writers Drew Simon and Mandy Gambrell contributed to this report.