A rail workers' union has called for an inquiry into "inadequately qualified" managers manning high voltage equipment during a five-day strike.
Rail officials said safety would not be affected during the strike
Electrical control room staff in York responsible for the 25,000-volt supply on the East Coast Mainline will start their strike from teatime on Wednesday.
The action is over proposed job cuts and union officials may ballot other staff "if safety is compromised".
Network Rail said managers covering the shifts were experienced staff.
In a statement the National Union of Rail, Maritime and Transport workers (RMT) said it was calling for an urgent inquiry amid fears that Network Rail would deployed "inadequately qualified" managers at the electrical posts.
The union has also warned Network Rail that if the company "proceeds with plans that undermine the safe handling of the 25,000-volt electricity supply" it will ballot other railway staff over action.
The union statement adds: "Our fear is that Network Rail intends to use managers who may not be fully competent in tasks that will prevent accidental electrocution of staff, passengers and the general public.
"We have told the inspectorate that any staff in these areas who work on or near high-voltage electrical equipment may be at risk from electrocution.
"Network Rail needs to be told that it cannot put our members and the travelling public at risk in an attempt to beat a strike."
Network Rail said the union's action would not jeopardise the "safe and reliable" running of rail services.
And officials said the union's fears over electrical safety were unfounded.
"Staff covering the posts are very experienced electrical specialists who have had additional training and are fully competent and able to carry out the task of electrical control room operator for the next five days."