dissenting:
I agree with the majority’s statement of the cost causation standard that governs the Commission’s ratemaking decisions. Maj. Op. at 1282-83. But I disagree that the Commission has satisfied that standard. Commission counsel admitted at oral argument that nowhere in the record is there a calculation of PG & E’s costs for standing ready to serve petitioners. Without that number or even a rough approximation of it, the Commission could not determine whether the rate PG & E proposed related to the costs these standby customers imposed. It is no answer to say that the standby customers must be imposing some cost on PG & E or that the 12-CP system may not adequately account *1287for the standby customer’s unpredictable usage. The questions remain — what is the amount of the cost and does that amount justify a rate four times higher than the rate PG & E would have charged under its 12-CP system. The Commission never answers either question and neither does the majority opinion.