The scope of this paper is limited to transformers stepping down direct to the 240-volt distribution system, and to the consideration of voltage ratio, tappings and economic size of standard transformers, with a few notes and curves giving the permissible duration of overloads, starting with a known oil temperature and air temperature. In Section 3 an attempt is made to compare the operating conditions for widely varying loads supplied from transformers without tappings, compared with the same loads from transformers with tappings. Section 4 gives the performance to be expected from existing transformers when the excitation is increased to give 433/250 volts at noload. A solution to the problem of using these transformers and still maintaining standard primary supply voltages is sought. In the author's opinion the problem can be solved if tappings are not used. The economic size of standard transformers to suit various load factors and types of load are considered in Section 5, using the utilization factor ? as the basis for selecting the size required. A standard range of sizes increasing in KVA rating in the ratio of 2 appears to be economic for the smaller sizes up to approximately 500 kVA, with one additional size between 500 and 1 000 kVA. A knowledge of the permissible duration of overloads when only the maximum oil temperature and the surrounding air temperature are known may be very useful; curves of these values are given in Section 6.