UPDATE 1-Refinery work sends LA gasoline up 8.75 cts-trade

(Adds Chevron El Segundo planned shutdown as cause)

HOUSTON, May 20 (Reuters) - Wholesale gasoline prices in the Los Angeles market jumped 8.75 cents per gallon Tuesday morning, and traders attributed the increase to work at a refinery.

Sources said Chevron Corp (CVX.N: Quote, Profile, Research, Stock Buzz) shut the smaller of two crude units at its 260,000 barrel per day El Segundo refinery for planned work, driving the price increase.

The surge occurred as the monthly contract nears expiration and at least one refinery was seen delayed in finishing maintenance, traders said. (Reporting by Erwin Seba; Editing by Marguerita Choy)