Utilising the standard AS/NZS 61000.3.6 to carry out a harmonic allocation to a load in a transmission system requires detailed knowledge of the location and magnitude of every future load. Given that the size of the load at a bus in a transmission system could conceivably be from zero up to around thirty percent of the fault level, such knowledge is unlikely to be available with any degree of certainty. This paper proposes an allocation policy which reduces the effect of load uncertainty, by allocating harmonic emission levels to areas comprising buses which are electrically close. Possible techniques are demonstrated using a simple test network. © Institution of Engineers.