The harmonic management of power systems in Australia is governed by AS/NZS 61000.3.6. This document is limited to a discussion of principles with little advice on detailed calculation. A Standards Australia handbook shows how the standard can be applied to find customer harmonic allocations for city and urban power systems. This paper further extends this work to rural power systems having the features of isolated lumped loads and radials with spurs. A general harmonic allocation equation is developed containing an allocation coefficient which is required to be found for each MV system. It is shown that the computation to find this coefficient can be simplified so that a small spreadsheet can be used.