Residential electricity rates fell on Oahu in September for the third consecutive month.

Hawaiian Electric Co. said a typical 600-kilowatt-hour bill for Oahu residential customers fell by $5.83 to $209.82 in September from $215.65 in August. The effective rate for electricity on Oahu is 33.50 cents a kilowatt-hour, down from 34.5 cents  a kilowatt hour last month. Electric rates also fell in August and July.

Elsewhere in the state:

— Maui Electric Co. customers saw rates fall to 34.9 cents per kilowatt-hour this month from 35.40 cents in August. The typical Maui bill fell by $3.18 to $218.12.

— Hawaii island residential rates rose to 40.7 cents a kilowatt-hour from last month’s 40.10 cents. The typical bill rose by $3.87 to $254.69.

— On Kauai, the rate rose to 40 cents per kilowatt-hour. Last month the rate charged by the Kauai Island Utility Cooperative was  38.4 cents per kilowatt-hour.

HECO adjusts its rates monthly largely to reflect changes in fuel costs. The utility generates 75 percent of their electricity from petroleum, making rates sensitive to volatility in oil prices.