<![CDATA[State-owned electricity utilities operate under demanding reliability, loss, and cost targets that depend directly on the performance of frontline and administrative staff, yet the internal conditions that raise that performance are seldom tested competitively in Indonesian service-unit settings. This study examines the partial and simultaneous effects of career development, supervision, and organisational culture on employee performance at PT PLN (Persero) Customer Service Unit (ULP) Kisaran, North Sumatra. A quantitative survey was administered to the entire population of 69 employees using saturated sampling, and the data were analysed with multiple linear regression in SPSS after instrument validation and classical assumption testing. The model was statistically significant, F(3, 65) = 10.21, p < .001, and explained 32.0% of the variance in performance (adjusted R² = .289). Organisational culture was the only significant unique predictor, B = 0.438, SE = 0.111, β = .432, t(65) = 3.95, p < .001, uniquely accounting for 16.3% of performance variance; career development, p = .125, and supervision, p = .126, were not significant. Two measurement findings qualify these results and are reported transparently: the supervision scale (α = .363) and the organisational culture scale (α = .556) fell below the .60 internal-consistency threshold, and all four scales exhibited pronounced ceiling effects. The non-significant supervision coefficient is therefore uninformative rather than evidence of no effect. Implications for shared-value management in utility service units and for instrument development in Indonesian human resource management research are discussed.]]>
