With the increasing number of HVDC interconnectors, HVDC from windfarms, HVDC  at Battery Energy Storage Systems and solar farms there is a need for an agreement on calculation methodologies for rise of earth potentials under HVDC fault conditions.  We are drafting a new standard within ISO (with CEN joint venture) in Technical committee 67, sub committee 2, working group 24.   (ISO TC67 SC2 WG24). It is a pipeline committee and the standard deals with the increased risk of corrosion to buried or immersed pipelines due to the AC and DC elements of these systems. One of the challenges we have is presenting an acceptable methodology for assessing the ROEP under DC fault conditions.   We want to avoid an over-dependence on modelling (e.g. FEA) so that engineers can perform the calculation themselves.  We have found that there is a common misconception that the criteria for AC fault current levels can be applied to DC fault conditions, and this is not true.  If anyone has any ideas or experience they can share, or wishes to participate in the working group please let me know.  I am the convenor and project leader for this work.