Botley Road engineering works which have been causing traffic congestion will carry on throughout the weekend and possibly extend into next week.
Scottish and Southern Energy is digging up the road in search of an underground cable fault which caused power cuts to 70 properties in the area.
The properties had power restored at 7am on Thursday but company spokesman Neil Anderson said: “It is an educated search for a needle in a haystack.”
He said engineers would work from 7am in the morning to 11pm at the latest to avoid causing noise disturbance. The firm is manually controlling temporary lights at the Ferry Hinksey Road junction.