Abstract
This paper presents the methodology and main results of the most recent Norwegian customer survey on consumer valuation of interruptions and voltage problems. The survey provided cost estimates that have been incorporated in the quality of supply regulation, in terms of the cost of energy not supplied. The data collected are also useful for different tasks related to value-based planning and operation of the electric power system. A combination of direct worth (DW) and willingness to pay (WTP) was used in the survey. The DW approach yielded significantly larger cost estimates than the WTP. The ratio of DW/WTP cost estimates varies in the order of 2-12 depending on customer group. There has been a real increase in the customers' costs since the 1991 survey for all groups and particularly for the agricultural group.