A drill has hit and damaged one of Brisbane's main power arteries, forcing the partial closure of the Victoria Bridge to allow Energex crews to repair the cable, which runs underneath the bridge.

The Victoria Bridge's westbound traffic lane, for vehicles heading from Brisbane CBD to South Bank, was expected to be closed for 24 hours from 5am on Thursday, but could be closed for longer depending on the severity of the cable damage.

An Energex spokesman said the 110,000-volt cable, described as "the main power artery that feeds Brisbane City", was damaged by a drill near the Cultural Centre on Melbourne Street.

The workers who damaged the cable were not Energex contractors and it was not believed there were any electrical shocks or injuries as a result of the incident.