AN optional-control system of domestic electricity supply is described by P. Schiller (J. Inst: Elec. Eng., 89, Pt. 2, No. 9 ; June, 1942), which is designed to meet the objection often raised to domestic load control of any kind, in that it involves encroachment on the consumer's liberty to use his supply as he wishes. It is suggested in the paper that the consumer be given the opportunity at any moment and for any period of time readily to change over from a controlled to an uncontrolled supply, and vice versa, the consumption during periods in which the load control is made inoperative being charged at a higher price. The price change can be effected by a gear-change, device in the kwh. register or in the prepayment mechanism of the meter, actuated in conjunction with the changeover in the operation of the load control. The necessary modification of apparatus and the extra cost entailed are both of a minor nature.