London Trams passengers, including those travelling to the Wimbledon tennis tournament, are facing disruption as some staff are due to stage a walkout later.
Maintenance workers who are members of the Unite union will strike from 20:00 on Sunday until 8 July, and will do so again from 11 to 15 July, in a dispute over pay.
Transport for London (TfL) said it expected a reduced and disrupted service on the whole of the London Trams network on some of the strike days.
On strike days there will be no service before 07:00 and after 18:00 with a reduced service from 07:00 to 18:00.
Planned engineering work on Saturday 6 July and Sunday 7 July will mean no London Trams services will operate east of East Croydon, TfL added.
TfL said buses and Overground services “are expected to operate as normal but could be busier”, adding: “Where possible, customers should consider walking and cycling for local journeys.”
The Unite workers first took strike action in March saying they are paid up to £10,000 a year less than their colleagues on London Underground, despite requiring the same qualifications and performing the same roles.
Unite general secretary Sharon Graham said: “TfL thinks it can employ these workers on the cheap and treat them as second-class employees.
“The situation is totally unacceptable and our members are absolutely right to take strike action. They have Unite’s unflinching support.”
Navid Golshan, general manager for London Trams, said: “We urge Unite to work with us to find a resolution and call these strikes off.
“Customers planning to use London Trams services are encouraged to check before they travel, allow extra time for their journeys, and check the TfL website or the TfL Go app for the latest travel information.”