Authors motivate and emphasize the TSLS re-estimation that instruments price to break the block-pricing simultaneity; the TSLS marginal-price elasticity (-.231) is their headline own-price result || 'When the model was reestimated with TSLS, the estimate of the coefficient of the marginal price variable remained negative and significant, but the coefficient of the inframarginal price variable became positive though insignificant. Together these results suggest electricity price elasticities are low though price is still an important determinant of usage levels.' (p.144)
Jaffee, B. L., D. A. Houstan, and R. W. Olshavsky (1982): “Residential Electricity Demand in Rural Areas: the Role of Conservation Actions, Engineering Factors, and Economic Variables.” Journal of Consumer Affairs 16(1), 137-151