A hearing aid comprising a housing with a connector enabling an external device to be connected thereto is provided. The connector includes a set of closely spaced electrical terminals operatively connected to at least one internal hearing aid component. The hearing aid also comprises detecting means adapted for determining whether an external device is connected or unconnected to the hearing aid, and the hearing aid is adapted for keeping the set of closely spaced electrical terminals at a substantially equal electrical potential during at least a part of the time periods wherein an external device is unconnected. A method of operating a hearing aid and a program comprising code adapted for operating a hearing aid is also provided.