Relative Influence of Rod Spacing and Length on the Thermal and Resistance Properties of Continuously Loaded Earthing Electrodes

Continuously loaded electrodes are a critical component in medium voltage Single Wire Earth Return (SWER) systems. Past electrode failures have encouraged the use of deep bored electrodes which can be expensive. This paper examines the use of multiple driven rod electrodes and explores the relative impact of rod spacing on both the steady state temperate rise and the electrode resistance to earth. A combination of analytical and finite element analysis are applied to determine the spacing requirements to simultaneously satisfy the electrode thermal and resistance constraints. This paper shows that the temperature rise constraints are more onerous than the electrode resistance or earth potential rise constraints.