Community leaders fear a child could be killed as they have been playing in open road holes containing electric cables.
Group members in Gleadless Valley say that youngsters were seen climbing into the holes on Fleury Road and Overend Road, which have been dug as council contractor Amey upgrades street lighting to new LED lights.
They should be surrounded by barriers, but some have been knocked down or taken in the area.
Brian Hanson, the community liason investigator for Gleadless Valley Community Action Group, sent in photographs of the holes.
He said: “What’s shocking is there is a live electricity cable on full public view every day. Children have been seen in and near the holes.
“The tenants of Gleadless Valley are worried in case a child gets killed while playing in one of those holes.”
The action group - as well as the Gleadless Valley Tenants’ and Residents’ Association - has complained to Amey about the problem.
Brian added: “The holes are still left unsecure.
“I am very concerned about the live electricity cables because they are not securely covered over to prevent children climbing into the holes and tampering with the cables.
“In my opinion these holes are a child’s death waiting to happen.”
The holes were dug to allow Amey to connect cables as part of the streetlights work.
Coun Jack Scott, cabinet member for environment, recycling and Street Scene at Sheffield Council, said: “I’m grateful to the residents in Gleadless Valley for bringing this to our attention and we are working closely with our Streets Ahead contractor Amey to sort this situation out as soon as possible.
“The safety of residents, road users and pedestrians is our number one priority and we do position barriers around all excavations across the city.
“Unfortunately we have experienced problems with barriers being knocked down in this area and have got crews regularly checking these. Sometimes, barriers are also taken.
“I would encourage all residents and children to take extra care around these holes. Although there is no immediate danger, people should not play in them under any circumstances. We need parents to be vigilant and make sure their children stay away.
“We would urge anyone who sees safety barriers that have been moved or toppled over in the wind to report them as soon as possible.”
Report missing barriers to customer services on 0114 273 4567.