Bosses from the Royal Wolverhampton NHS Trust confirmed they would only see a "minimum" impact as Royal College of Nursing (RCN) members walk out.
It is due to the threshold needed for industrial action not being met at the organisation, which runs New Cross Hospital, and at the majority in the Black Country.
However strikes will still take place at other sites in the region on December 15 and December 20, with chiefs keeping an eye on requests for leave over the dates.
Alan Duffell, chief people officer at the trust, told a board meeting a "lot has been done" to ensure the organisation is protected over the two strike days – but he said it did not make them "immune" from the impact industrial action has.
Meanwhile chief operating officer Gwen Nuttall, who heads up a group which meets weekly to discuss the issues, said: "Clearly, the key ballots have been around nursing in the first instance.
"The risk to the organisation on December 15 and December 20 should be at a minimum because staff at the trust have not voted to strike, but we need to be mindful of the situation and will monitor requests for annual leave and sickness – being open and transparent."
Ms Nuttall said there were still unions taking action which the trust needed to be prepared for – such as the GMB union members who have voted for strike action at West Midlands Ambulance Service.
The walkout date will happen on December 21 with Unison, GMB and Unite all walking out in a move which will affect non-life threatening calls only. It could mean people who have had trips and falls are not responded to.
The impact of the walkout will be patchy as Unison, which has twice the numbers of the other two unions combined, only has a strike mandate for half of England's 10 regional services.
Ms Nuttall said discussions will be held with the ambulance service over any impact, with the trust also wary of midwives, psychiatrists and junior doctors potentially all taking strike action.