The Rail, Maritime and Transport union said its members would walk out for three days from July 8, and accused Northern of “digging its heels” in over committing to a second member of staff in carriages.
But the company said it had invited the union to talks and that it had guaranteed jobs, current pay and annual pay reviews.
The operator said it would “keep customers on the move as much as possible” during the Saturday, Sunday and Monday strikes on the eve of the busy Great Yorkshire Show.
Richard Allan, Northern’s deputy managing director, said: “The RMT’s dispute will be solved by talking, not by unnecessary strike action which impacts our customers, our employees, businesses and the economy of the North.”
He added: “We are deeply disappointed and hugely frustrated that RMT is choosing to cause more pain for our colleagues and customers rather than get round the table to talk first.”
The union’s general secretary, Mick Cash, claimed Northern’s parent company, Arriva, had “upped the ante” by “demanding” it attended talks to discuss the implementation of proposals to which it was opposed.
He added: “The sheer intransigence of Arriva Rail North means that we have no option but to confirm a further round of strike action.”
The union has been in dispute with Southern Rail over the roles of guards for more than a year, crippling its services into and out of the capital.
Today, the publication of a long-awaited report into the Southern dispute was deeply critical of the RMT and the drivers’ union, Aslef.
The report, by Network Rail director Chris Gibb, said the unions were the “primary cause” for the system integrity to fail, by taking strike action, declining to work overtime and “generally not supporting and undermining” the system.
He said: “Their action is undermining the system, and its value to the country that funds it through fares and taxes.
“Whatever their motives, which are debatable, I do not support their action.”
Northern has been hit by three strikes so far this year. The union has said that its previous walk-outs had been “highly successful”, although trains on many routes continued to operate to a near-normal timetable, until around 5pm.
The union says guards fulfil a “safety critical” role on trains - a claim denied by operators. Northern’s new franchise, which began last year, requires it to operate half of its trains as “driver controlled” services in the future, though it has yet to announce plans.
Trains in some other parts of the country have operated without guards for several years.