This paper describes the design of yielding members to be added to the porcelain columns which support 80 ton smoothing reactors of the N.Z. Electricity Department's High Voltage 
Direct Current transmission system, in order to improve their earthquake resistance. It shows how the extent of the yield was estimated from the response spectra given by P.C. Jennings in "Earthquake Response of a Yielding Structure" and how the margin against collapse was estimated from Jennings and Husid's "Collapse of Yielding Structures during Earthquakes".