Copper vandals have shifted to targeting Kenya Power cables used in underground connection, threatening the firm's effort to reduce outages and stabilise supply.
Going under, which has seen Kenya Power spend billions in major towns, was billed as among the most secure ways to keep cables away from vandals but the cartel has taken the same route.
An attempt to vandalise a section of the 220 kilovolt (kV) line, which evacuates bulk power supply from Embakasi substation to the city centre, near Lang'ata Estate has sent stakeholders back to the drawing board on how to secure their lines.
Energy Cabinet Secretary Charles Keter said there are plans to upgrade systems to detect such breaches given the high cost associated with repairing vandalised copper.
"They use very crude methods, including lighting fire on the sections used to cause a blackout then cut the wires.
"The one in Langata alone will cost us Sh600 million to repair fully and put in measures to detect such breaches before they interfere with power supply," Mr Keter said Tuesday.
Kenya Power Managing Director Bernard Ngugi said the firm had laid close to 600km of its network in Nairobi and other major towns underground in an effort to keep it out of such interferences.
The total length of underground network of medium voltage lines (33kV and 11kV) lines in Nairobi and other major towns is 521km, while that of high voltage lines (66kV) is 66 km.
The 16km of 220kV electricity transmission cable from Embakasi to the Nairobi central business district was part of a Sh13 billion plan for the city's network improvement that also involved building substations and power lines around Nairobi.
"The company is continuously reviewing the performance of the network and trends in urbanisation to make decisions on investment in underground cables," Mr Ngugi said.
The Energy Act classifies electrical equipment vandalism as an economic crime, punishable by a minimum fine of Sh5 million or a minimum jail term of 10 years upon conviction.