Four electricity pylons collapsed following several blasts in Sharqiya governorate, north east of Cairo, the state owned MENA news agency reported Thursday.
No casualties were reported, but power outages hit some areas supplied by these units.
Unknown assailants planted improvised explosive devices at the pylon bases located near Zagazig and Qenayat towns in the governorate. They detonated almost simultaneously.
The general manager of Sharqiya power network, Hamdi Metwalli, said that bombs were planted at nine electricity pylons in the governorate over the past 24 hours. They include five in the industrial 10th of Ramadan City and four in Zagazig and Qenayat.
He added that the damage is estimated at LE9 million.
Small bombs had detonated at electricity pylons late Tuesday and early Wednesday in 10th of Ramadan City, near the industrial district, where most factories are located.
The 10th of Ramadan City, one of Egypt's most prominent industrial cities with a population of 250,000, is known for engineering, chemical and textile industries.
Police are investigating the incidents.
In recent months, Islamist militants have increasingly attacked economic targets in urban areas across Egypt, such as pylons and mobile network stores.
Egypt is set to host in Sharm El-Sheikh on 13-15 March a major international economic conference aimed to attract significant investment to bolster its economy.